The external morphology of the Mormon ( simplex Haldeman) with special reference to exoskeletal factors involved in the penetration of sodium arsenate dust by Leo W Tannenbaum A THESIS Submitted to the Graduate Committee in partial fulfillment of the requirements for the degree of Master of Science in Entomology Montana State University © Copyright by Leo W Tannenbaum (1941) Abstract: The external morphology of the was studied In Its entirety In order that exoskeletal factors Involved In sodium arsenlte penetration might he better understood. Of special Interest were thorax modifications. The mesothoracic spiracle is unusual because it consists of two separate openings leading into individual tracheae. Twenty-three figures of the Insect1S anatonyr sure here included. After trying some thirty plastics and paraffins a paraffin melting at 38-40°C was used to localize sodium arsenlte penetration. A simple test for cricket normalcy was devised. It was noted that crickets go through definite stages in their ability to react to simple stimuli after the sodium arsenlte applications have begun to penetrate. Mne lots of the Mormon cricket were dusted on different parts of the body to determine if preferential penetration exists. Applications to membranous areas which are not too smooth resulted in earlier reactions and slightly earlier 50% mortality points. Wide portions of sclerotlzed areas were not far enough behind in this respect to be significant. It was concluded that other factors besides degree of eclerotiration, such as position in respect to major organs, were of great importance and would modify the results. Analysis indicated that time of death and amount of penetration of sodium arsenite are not closely related. IHB SXTBEKAl MOEPHOLOGY 07 THB MOEMON CMCKBT (Anabrus simplex Haldeman) WITH SPBCIAL HBTBEBNCB TO BZOSKELETAL FACTORS INVOLVED IN THE PENETRATION OF SODIUM ABSBNITB DUST By LEO W TANNENBAUM

A THESIS Submitted to the Graduate Committee in partial fulfillment of the requirements for the degree of Master of Science in Entomology at Montana State College

Approved:

In Charge of Major Work

Chairman, Examining Committee ythairman, Grathiate Committee

Bozeman, Montana Jbne1 IgUl H 3 1 % T / f * -

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TABLE OF CONTENTS

P a g e A bstract ......

Introduction ...... U

Section I, External Morphology ...... Review of Literature on Morphology

Head ...... • vi vi vn Thorax ...... 16 Abdomen...... 28

Abbreviations and lettering on Plate Figures ...... 32

P la tes ...... 35

Section II, The Penetration of Sodium Arsenite through the exoskeleton ...... W Review of Literature on Penetration of Sodium A rsenite ...... lj.0 Procedure ...... U2

Effect of Dusting the Abdomen with Sodium Arsenite ...... U9

Effect of Dusting the Thorax and its ...... 57

General Considerations ...... 61

Conclusions ...... 614-

Literature Cited and Consulted ...... 66

6 6 1 2 4 ABSTRACT

The external morphology of the Mormon cricket was studied in its entirety in order that exoskeletal factors involved in sodium arsenite penetration might he better understood. Of special interest were thorax modifications. The mesothoracic spiracle is unusual because it consists of two separate openings leading into individual tracheae. Twenty-three figures of the Insect1S anatonyr acre here Included, After trying some thirty plastics and paraffins a paraffin melting at 38-40*0. was used to localize sodium arsenite penetration. A simple test for cricket normalcy was devised. It was noted that crickets go through definite stages in their ability to react to simple stimuli after the sodium arsenite applications have begun to penetrate. Uine lots of the Mormon cricket were dusted on different parts of the body to determine if preferential penetration exists. Applications to membranous areas which are not too smooth resulted in earlier reactions and slightly earlier 50# mortality points, fide portions of sclerotized areas were not far enough behind in this respect to be significant. It was concluded that other factors besides degree of sclerotiration, such as position in respect to major organs, were of great importance and would modify the resu lts. Analysis indicated that time of death and amount of penetration of sodium arsenite are not closely related. -U- INTEODUCTIOE .

The Mormon cricket, Anabrus simplex (Eald1) , is an important pest of several agricultural and range crops in Montana and certain other Western states# Control in recent years has consisted, for the most part, in the use of sodium atsenite as a dust. This insecticide has been of general use throughout those states infested. Although it is known to be a powerful poison little is known either of its method of penetration or of the exoskeletal factors involved. Since penetration does take place through the exoskeleton, the outer parts of the influence it and may well be factors regulating the efficiency of control. This paper has a twofold purpose: (I) a study of the external morphology of the Mormon cricket so that the exoskeletal areas may be better understood, and (2) experimental determination of the barrier the major exoskeletal areas offer to penetration of sodium arsenite dust. To carry out the first purpose a complete study of the external morphology was made. To carry out the second purpose, experiments were conducted to determine or gather information on the following points: (I) the possible existence of parts of the cricket more susceptible to penetration than other parts, and (2) the relation of amount of penetration to the time necessary for fifty per cent mortality.

The author is greatly indebted for suggestions and criticism to Dr. H. 3. Mills under whom this study was conducted. Mr. Ellsworth Hastings has taken a kind interest in chemical aspects of the work, and Dr. G. C. Crampton, of the Massachusetts State College, has offered valued criticism in its morphological aspects. Mr. D. J. Pletsch has been most helpful in matters dealing with illustrations. All these kind services are greatly appreciated by the author. -5 - Section-I

EXfSHNAL MOHPHOLOGFr

No complete morphological study of a decticine Orthopteraa is available in the literature. Snodgrass (I909), in discussing the thoracic sclerites of the various Orders, illustrated three views of the me so thorax of Anabrus simplex. The same author (1957) in considering the male genitalia of Orthopteroid discussed the male term!naila of this species. Insects in related groups have been treated in greater d etail. Crampton (1930) made a detailed study of the head of Stenopelmatus. The same author in a series of papers (1915-1938) paid special attention to the phylogenetic relationships of the Orylloblattidae and other Orthopteroide, and studied in a comparative fashion the head, mouthparts, and thoracic sclerites in and related orders. Walker in a series of papers (I919-I933) dealt with subjects in the same general manner. Of especial interest to this study are this author's papers (1919b, 1922) on the terminal structures' of Orthopteroid insects. Tuasa (I920) studied the anatomy of the head and mouthparts of Orthoptera. Oumey (1936) made a complete study of Ceuthophilus and its phylogenetic position.

Train

The head of Anabrus is similar in many respects to the heads of Stenopelmatus and Ceuthophilus. The marked, broad dorsal roundness and the smoothness of Stenopelmatus are lacking. These differences may be related to the differences in habit since Anabrus does not burrow as does Stenopelmatus. In its more general characteristics the head of in.trus is more like that of Ceuthophilus since antennae and eyes are more centrally _6_ as well as more dorsally located. These characteristics may he taken for evidence that Anahms has departed further from the more primitive type than has Stenopelmatus. Head capsule: When seen from in front as shown in fig. I, the head capsule of Anahrus is ohlong-ovoid in shape. The coronal suture Cs which represents the stem of the Y—shaped epicranial suture is plainly hut not strongly demarked. It extends centrally terminating at a point near the distal end of a prominent raised process, the fastigium, fas. The latter is homologous with the process.occurring in Llcodla, Paranahrus, Ceuthophilus and other genera, frontal sutures, which represent the arms of the T-shaped epicranial suture, are not present in Anahrus. Immediately helow the fastigium, fas, and almost at right an&les to the line of the coronal suture, Cs, are suture—like folds caused hy the close proximity of antennal sockets and fastigium, fas.

On each side of the coronal suture Cs are the regions known as •• parietals par. The areas above and behind the compound eye e are the temples or teopora te. The regions helow and behind the eyes are the cheeks or genae ge. Above the compound eyes e and extending toward the postoccipital suture pos of fig. 2 is a suture here considered to he temporal suture tes. Because there are no frontal sutures the frons f may he considered to be the area below and between the antennae extending down to the frontoclypeal suture fee. Beneath the gena ge and separated from it hy the eplstomal sdture eti is the eubgena or hasimandihulare hm. The latter is separated from the mandible md hy the baeimandibular membrane bmm. In the Mormon cricket each epistomal suture es extends - 7 - mesad meeting its fellow on the other side. The portions of the eplstomal sutures es between the frons f and the clypeus c comprise the frontoclypeal suture fcs. Zn Anabrus coincident with the sutures labelled es are the frontal pits the roots of invaginations forming the pretentorium gt of fig. 5» Anterior to the frontoclypeal suture fos is the clypeus c. If the head capsule be viewed from the rear as in fig. 2 the postgenal suture pgs may be seen to separate the genae ge from the post- genae pge. The postgenal suture pgs leads upward from the subgena bm and is lo st or discontinued in the occiput. In Anabrus i t meets two thickened or buttressed areas. The lower one labelled bu is an easily seen thickened area between the postgenal ridge pgs and the postocciptal suture pos. Slightly above this area and running through the terminus of the postgenal suture pgs is the temporal suture tea. Eyes: The compound eyes e are not very large but are relatively larger than, the eyes of Stenopelmatus and CeuthophiIus. This may be in line with the suggestion of Crastpton (1930) that there seems to be a marked correlation of Insects having both small eyes and long sensitive.antennae in insects with hiding habits. Anabrus with less marked hiding habits than the two above mentioned genera has larger eyes and relatively shorter antennae than Ceuthophllus. The ocelli in Anabrus are vestigial and may be non-functional. The median ocellus is present as a light spot below the fastiglum fas. The lateral ocelli are present as similar spots at about the widest point of the fastiglum as shown in fig. I. Occipital region: The postoccipital suture pos of fig. 2 separates the postgena pge from the postocciput go. The postocciput go -g- "bears a pair of processes, the occipital condyles occ upon which the lateral cervical plates are articulated. The occipital condyles in Anahrus are small sclerites which are folded on their long axes. They are separated from the postocciput merely hy grooves. Posterior to the suhmentum sm and the post­ occiput £0 is the membrane of the cervix. I f th is membrane be removed a posterior view would be had of the posterior tentorial arms poc and the occipital foremen ocf of which an anterior view is had in fig . 5» Tentorium: The tentorium is the endoskeletal portion of the head capsule. It is very similar to the type seen in the more generalized Orthopterold insects. The tentorium is formed by invaginations of the head capsule. ‘ If the labrum, clypeus, and the anterior portion of the head capsule be removed from a IO^ KOH preparation the parts of the tentorium may be seen as in fig. 5« The anterior arms or pretentorium jrt extend backward from the frontal pits f£ of fig I as invaginations. The dorsal , arms or supratentorium st^ are of a thin and tendonous nature and rise anterior to the body of the tentorium or eutentorium eu. Immediately anterior to the body of the tentorium eu is the neural foramen nf. Through the neural foramen pass Commissures connecting the brain and the suboesophageal ganglion. Extending forward from the gular pits g) seen in fig. 2 as invaginations are the posterior arms of the tentorium or parocclput poc. The posterior arch £ is also a result of the invagination. The body of the tentorium eu may be considered as a fusion of anterior and posterior tentorial arms. In fig . 5 also, may be seen an ental view of the rear portion of the head capsule. Besides the added strength given to this portion by a thick parocclput poc there is further buttressing bu above the parocclput. The postgenal process ££ is also thickened in that area within - 9 - the dotted line In the figure. In the postgenal process Is the post- genal acetabulum pga a socket for the hypo condyle h of the mandible seen in fig. It. Along the lower edge of the postgenal process is a thickened marginal area, the parastomlua pst.

HMD APPENDAGES

Antennae: About the base of the is a ring, the antennale an of fig . 3. In Stenopelmatus and Ceuthophilus the antennale bears a median projection for pivotal purposes, the antennlfer. In Anabrus the antennlfer is lacking. The basiscape of Stenopelmatus and other insects is also lacking in Anabrus. However, there i s a small "inpushed" tendon- connection (in the membrane immediately anterior to the first antennal segment) which helps in moving the antennae. The antennae are long and thread-like, in most cases slightly longer than the body. The number of antennal segments is variable,in some specimens reaching more than one hundred and forty. The first antennal segment or scape sc is broad and flattened. Basally it has projections which aid in pivoting the antennae. The segment next to the scape, the pedicel gd, is more cylindrical and is followed by the postpedicel ppd. The postpedicel and a ll other segments d istal to i t are known collectively as the flagellum. Ragellar segments may be divided into the short segments or brachymeres, and long segments or dollchomeres.

- - ... - - , . - ' - , . In Anabrus long brachymeres lb , short brachymere eb, and slender dollchomeres sd, may be easily distinguished. Intermediate types are also present. Clypeus and labrumt In many insects the clypeus may be divided by differences such as coloring into a posterior postclypeus and an anterior -1 0 - anteclypeus. This division is apparent only faintly in Anabrus, I f the lahrom la and clypeus c are inspected from an Inner or hoccal view as in fig .7 the epipharynx may he seen. The greater part of the epipharynx is covered hy fine sensory hairs. Two main divisions may he distinguished, an anterior preepipharynx pre and a posterior post epipharynx poe. These two areas correspond to the lahrom and clypeus respectively. The epipharyngeal area has several small sclerites. The tormae to are a pair of small sclerites situated near the lahro-clypeal lateral angles, and thus delimit the lahrum and clypeus. Between the lahrum and clypeus and extending transversely between the tormae is a small sclerite, the lntertorma i t . Mandihle: Beneath the hasimandlhular membranes bmm of fig. I are the paired jaws or mandibles md. The mandible is roughly pyramidal in shape and the space within it is filled with tissue. The base is triangular and there are three faces. In fig. 4, a posterior view of the dextral mandible, the rear face may he seen. Bie apex of the roughly pyramidal mandible is the tearing area or gnathapex ga. The grinding portion, or mola m is proximad of the gnathapex. A hrustla or brush hr is present on the biting edge near the base. The base of the mandible has two articulatory points. The posterior articulatory point, the gn&thocondyle or hypo- condyle h of fig. 4.fits into the postgenal acetabulum pga of the poetgenal process ££ shown in fig. 5» Anterior articulation for the mandible is afforded by means of the ginglymus gi. The glnglymus (shown in fig s. I and 4) fits into a groove in the side of the clypeus. To the extensor prominence go (on the outer edge of the mandible near the hypocondyle h) is joined the extensor tendon et which helps open the mandible. Near the - l i ­ me dl an ridge of the mandible, at Ita base, la the tendon, eclerite or gnathite Qi to which ia attached a large flexor tendon f t. In Anabrns both the gnathite gn and flexor tendon ft are slightly modified from their homologs in Centhophilns and Stenopelmatns. The gnathite gn is not readily distinguishable as a separate aclerite and is fused with the flexor tendon ft. The flexor tendon is very.large since it ia in closing the jaws during chewing that strength is most needed. At its base it extends more than half the distance to the gnathocondyle h. Extending inwardly, the flexor tendon ft is composed of one large posterior portion closely apposed to the base of three additional narrow branches. The endognath eg is an internal; shblf at the base of the mandible.

Maxilla: In fig. 2 there may be seen a posterior view of the sinistra! maxilla. The labium and hypopharyngeal regions are connected to the maxilla by means of the basimaxillary membrane b. The basal segment or cardo of the maxilla is divided by the cardinal suture or cardosuture cds into a basal basicardo be, and a distal distlcardo do. Distal to the car do are the stipes £ and the parastlpes ps which are separated by the parastipltal suture pss. When the posterior side of the car do and stipes are viewed entally as in fig. 6 an internal ridge, the endocardo ec corresponds to the cardosuture cds, and another internal ridge, the endostipes eet corresponds to the external parastipltal suture gss of fig. 2. The internal ridges offer additional support to the maxilla and afford places of attachment for muscles. The endo stipes est affords attachment for the flexor muscles of the maxilla. The distlcardo dc is enlarged by an extruding bulge which supplies space for_rauscles. A process not seen externally (unless the -1 2 - maxilla Is pulled out) the cardoprocess offers attachment to the car do tendon ctn. The extensor muscles act In conjunction with the latter to open the maxilla by pulling it away, laterally, from the mesal part of the head. The condyle acting in this operation is the articulatory process of the basicardo d which pivots externally on a process of the parocciput poo. In Anabrus a division of the stipes into basal and distal regions is not perceptible, A small region the palpifer gf is clearly seen. It bears the five-segmented maxillary palpus mg. The fifth segment of the maxillary palpus bears a rather large sensitive area at its tip. The stipes s bears distally an outer galea and an inner lacinia I. The galea is divided distinctly into a baslgalea bg and a distigalea dg. In Anabrus the baslgalea is not much wider than the distigalea at their juncture and the latter is blunt, not slender and graceful. In fig. 9» an anterior or mesal view of part of the maxilla, five sensory areas may be seen on the galea. A large area at the tip of the distigalea is obvious; basad of this and indicated by fine lines are four less easily distinguished sensory areas the function of which is obscure. At the distal end of the lacinia I are two tooth- like projections the laciniadentes Id. A third process the lacinula Iii is joined to the lacinia by means of a socket which can be better seen from the anterior view. The lacin ia bears a fringe of setae on i t s mesal border. In Anabrus there is present also, on the anterior face of the lacinia, a process with probable sensory function which is similar in appearance to those on the galea. Labium; The labium may be seen in fig. 2. The glossae gl and the jparaglossae pgl are attached to the gloss!ger gg. The portion of the -1 3 - labium immediately "baead of the gloeaiger gg is the labial stipites 11_. In Anabrus demarcation of the gloseiger gg from the paragloeeae pgl and gloesa gl is more easily distinguished on the posterior than on the anterior face of the labium. On the anterior face as shown in fig. 8, the line of division is not perceptible. A basal area the basigloesa bgl may be seen basad of the glossa gl. Sutural division between the lab ial stipets li_ and glossiger gg may be seen as in fig. 2. The palpiger gg is lateral of the sclerites 1JL_ and bears the three- segmented labial palpus l£. Orampton (1930) has discussed the theories on homologies of lab ial and maxillary parts mentioned above. The lab ial stip ite s 11 and the men turn mn are separated by a membranous area. The rnentua mn is d istinct in Anabrus. I t has a notched appearance d lstally . To the mentum are attached internally muscles which move the labium. In Anabrus latero— basal to the mentum are the anterior arms of the submen turn asm (anterior arms of postmentum of Snodgrass) which extend back to the main body of the submen turn sm. The large membranous area between the anerior submental arms and between the mentum and submentum is the submental mmnbrane. I t two degrees of membranization. The portion between the anterior arms behind the dotted line shown in fig. 2 is slig&tly darker and harder than that portion immediately anterior to it. In insects of this rather primitive hypopnathous type the gular region is generally considered to be the rear portion of the plate labelled sm, or alternatively, that it has not yet developed as in the more advanced prognathous type. The gular pits gjj are situated near the base of the plate labelled sm. They are the openings to invaginations which form, the posterior arms of the tentorium poc of fig. 5. There is no poetgular plate as there is in Stenopelmatus. Hypopharynx: t The hypopharynx h£ of fig . 10 is a fleshy tongue- like structure found in the median ventral part of the head "between the lahrum and lahimn. I t is very much like the hypopharynx of Stenopelmatus. In fig. 10 the hypopharynx h£ is seen- to he composed of several p arts. The distilingua dl is the region at the free end. It is sclerotized for the most part hut portions are very thin as shown in fig. 10. The hasal region of the hypopharynx is composed of a dorsal dorsollngua or surlingua si immediately anterior to the mouth and a ventral membranous basllingua hi. The salivary

. duct opens into the hasal hasillngua above the labium. In Anabrus on the side walls of the dietilingua dl a pair of plates afford attachment for the hypopharyngeal retractor muscles. A slender sclerite the lingualora 11 is:, in the hasal portion of the hypopharynx as is also the postlingua p i. -1 5 - CEEVIX

The cervix Ie the membranous neck region Immediately behind the head and immediately anterior to the pro thorax. In Anabrus the cervical area Is much larger than it appears since normally it is partially concealed beneath the anterior border of the pronotum. In figs. 13 and Ig the cervix is shown to have three pairs of plates. The large lateral eclerite Ic of fig. 13 is the laterocervicale. It is one of a pair, its fellow being on the other side. The anterior end of the laterocervicale Ic articulates with the occipital condyle occ of fig. 2. Ventrad of these as seen in fig . 18 are the ventral cervical sclerites vc. Dorsad of the lateral cervicales are a pair of small dorsal cervical sclerites dcs connected so closely mesally as to suggest that they are a single central sclerite. -1 6 -

thorax

The thorax of the Dectlclnae has been little Investigated. Snodgrass (1909) drew three views of the mesothorax of Anabrus. Most notable In the anatomy of Anabrus Is that elongation of the pronotum has been accompanied not only by prothoracic modification but also by modification of the pterothorax as well. In Anabrus the tegmina have been so shortened that in the male they reach only to the middle of the first abdominal terg ite and in the female they are even shorter. The wings in both sexes are represented only by membranous pouches. The thoracic epiracular apparatus offers an interesting modification which may be seen in certain other insects of the subfamily.

PROTHORAX

Pronotum: The pronotum pn of fig. 13 extends back from the membrane of the cervix to a point above the middle of the metathorax. It is free dorsally from a point anterior to the meso thoracic ter gum. The pron­ otum jjn covers the epi sternum eps^and the epimeron epm^ so that they are only p artia lly v isible. In this study specimens of Anabrus simplex examined from Montana and eastern Idaho, the pronotum was found to be very smooth and carinae and sulci were only very faintly indicated. Gurney (1939) stated that carinae are rare in the except in Anabrus loagipes but suggested the possibility of longipes being a subspecies of simplex. As in other Orthopteroids, Anabrus has no prothoracic spiracle. Propleuron: The first portion of the propleuron Is a narrow border-like sclerite, the prepectus ppc, which extends ventrally and -1 7 - contlnuously through the sternal area. . The dorsal terminus of the prepectus ppe Is coincident with that point at shich the eplsternum eps^ls overgrown hy the prono turn pn> The epl sternum eps^ls closely united with the pro no turn. If the prono turn is removed the epl sternum is seen to he almost triangular in shape and to extend almost to the dorsum. At i t s hase the epl sternum is continuous with the precoxale prcx^. The pleural ridge plr is a me sal . inflexion of the epl sternum extending along its posterior edge. At its lower portion the pleural ridge is represented externally hy a suture, the pleural suture pis which separates the episternum eps from the epimeron epm^. In the generalised thoracic segment the pleural ridge hears an internal arm or apophysis which is closely associated with the ventral apophysis (furca). The pleural apophysis is absent in the pro thorax of Anahrus. Unlike most Orthopteroids the epimeron epm^ of Anahrus is a short sclerite. The major portion of the epimeron has been lo st and as may he seen in fig . 13 only enough of the epimeron exists for the pronoturn to overlap. The short­ ness of the epimeron is a useful adaptation since i t allows for more flexible movement of the prono turn. At the basal extremity of the external portion of the epi sternum in Anahrus there is a small sclerite upon which the trochantia tn^ pivots. The small sclerite is very probably a portion of the primitive coxopleurite, part of which has fused with the anopleurite to form the pi euro n and part of which has remained a free sclerite, the trochantia tn^. Prosternum: posterior to the prepectus ppe of fig. IS is the has!sternum hs; The furcal pits fup are the outward evidences of sternal apophyses which form the furca fu^. The furcal p its fup are inwardly connected hy a ridge or stemacosta of which the outward evidence is, in

Anahrus, a groove the stemaeostal suture stcs. The stemacostal suture -IS- dlvides the eusternum into two parts. The anterior part is the has!sternum hs; the posterior portion is the sternellum or furcasteraum fs. The furca is useful for support of the prothorai and for muscle connection. Posterior to the furcasteraum fs^ and separated from the latter hy a narrow membranous area i s the spinasternum ssj which in Anabrus is a very narrow transverse sclerite. The spinasternum ss bears the spinal pit spp an out­ ward evidence of an internal apodeme, the spina spi. The spina in Anabrus is roughly hammer-like in shape.

PTEROTEOBAX

Mesonoturn; In fig. 14 the dorsum of the male pterothorax is shown. Immediately behind the lntersegmental maabrane is the acrotergite atgg of the mesothorax. The antecostal suture acs divides the acro­ tergite atgg from the prescutum psc. Internally the suture is represented by an apophysis or prephragoa gh. The prephragma ph of fig . 14 is shown as in the male. In the female the prephragma ph is shorter. The scutum set is the area immediately behind the prescutum psc. In Anabrus the scutum is marked sparingly with setae. The slightly raised area behind the scutum set is the scutellum gel. Extending poster!ad from the ante- costal suture to opposite the rear tip of the scutellum and running along the side of the processes mentioned above are the maxillary sclerites by means of which the tegmen is articulated. These sclerites will be discussed under "articulation of the wings". In the male Anabrus the posterior part of the mesonotum is folded under immediately behind the scutellum scl and then refolded to form the postecutellum pscl. The first -1 9 - fold, visible as the posterior sclerite of the eunotum is the posttergite the female cricket the postscutellmn is absent. The spiracles s^ are considered part of the ter gain thron^iout the body. Anabrus presents a special modification of the mesothoracic spiracle sp^ of fig, 13 ^diich is not evident in Staiopelmatus or Ceutho— phiIus. In the membrane between the propleuron and mesopleuron of fig. 13 there may be seen a "biforous" spiracle. The meso thoracic spiracle of Anabrus consists of two openings each of which leads to a trachea. The larger (posterior) opening is unusual for an Orthopteroid in that it is guarded by numerous tiny eatae. This large opening gives immediate entrance to a large air-sac type of trachea. The smaller, anterior opening is guarded by two small sclerites, The posterior sclerite appears to be part of the :peritremall sclerite of the posterior opening. The smaller opening gives immediate entrance to a small trachea. The tracheae of both entrances do not lead into a common chamber and apparently are in no way connected. Although this is not a respiratory study a b rie f note on the tracheae involved will not be out of place. The large air-sac type of trachea is connected transversely with its fellow on the other side of the thorax by means of a very narrow trachea. From the body of the sac a large trachea leads directly to the front leg. The large trachea is about one-third the diameter of the leg itself and extends down the leg past the auditory apparatus aa of fig. 12. The smaller (anterior) trachea extends cephalad. It bears several branches at the head. Midway between the head branches and the orifice this trachea gives off a branch sharply in a ventral direction. This branch divides several times also; one of the subsidiary -2 0 - tranches descends to the front leg and another to the long ventral tracheal chain.

Metanoturn; The metanotmn of Anabrug is somewhat lik e the meso- notum. The acrotergite atg^ is followed by the prescutum psc,. The prephragma ph, is much smaller than in the mesonotum. The scutum set is anterior to the scutellum scl. In Anabrus both sexes lack the metathoracic postscutellum or postnotum. To the dorsolateral area, to iriaich is articu­ lated the wing in the mesothorax, is attached a membranous wing pouch wj. Mesopleuron? Snodgrass (1909) drew figures of the internal and external mesopleuron of Anabrus simplex. This author points out the existence of a preepisternum homologous to that seen in Qryllus. Djseosteira, ®nd Melanoplus. The sclerite in question is separated from what Snodgrass (1909) called episternum by a suture which runs almost the fu ll length of the epi sternum. Gumey (1936) noted the existence of "a lengthwise suture" on mesopleuron and metapleuron in Ceuthophilus. These sutures would appear to be homologous to those sim ilarly placed in Anabrus. In this paper, the preepi sternum w ill be considered merely as part of the episternum, and that the episternum epsg is separated from the epimeron 2E2 V the pleural suture. The pleural suture pis is represented internally by a pleural ridge which extends down from the wing process wgg of fig. 13 to the pleural coxal process. The pleural ridge of the mesopleuron branches near its upper extremity and comes forward to support the epi sternum. The anterior portion of the epi sternum is divided trans­ versely by a suture. At the base of the tegmen are two paraptera. The one anterior to the wing process wp^ is the basalare bag, that posterior -2 1 - to the wing process wp^ Is the euhalare sa^« Both are aids In wing manipulation and are used for muscle attachment. The pleural apophysis pla is an invagination forming an internal arm continuous with the pleural ridge. The pleural arm is closely associated at its distal end with the furca. The precoxale prcxo of the mesothoracic pleuron is hasally contigu­ ous with the base of the anterior episternum (preepisternum of Snodgrass). It should he noted in fig. 13 that the precoxale of the mesothorax is considerably shorter than the one present on the propleuron. Metapleuron; The metapleuron is very much like the mesopleuron. Perhaps the most striking difference is the modification attendant to the atrophy of the wings. In Anahrus neither sex is able to . The anterior and posterior la te ra l edges of the episternum eps, have fused with the metanotum mtn of fig. 13. The wing process wgj has not only fused with the no turn but also has fused with the subalare sa,. The basal are ba, is —J —J closer to the epi sternum eps^ (being separated from the la tte r only by a suture) than the corresponding parts of the mesothorax. The suture which divides the episternum eps? into two parts does not run through the fu ll length of the latter. There is no precoxal bridge in the metapleuron. Mesosternum; As shown in fig . 18 the mesothoracic baslsternum of Anabrus is divided into two parts, the anterior basisternum abs2 and the posterior basi sternum pbs^,. The anterior basi sternum absg is composed of two roughly quadrate sclerites which are projected well below the level of surrounding membrane. Two broad spines project below the basal portion of the posterior basi sternum ^bs2. Immediately posterior to the spine- bearing process there is a median triangular impression in the sternum. -2 2 - The triangular area hears the roots of three apophyseal processes which form the furca fu^. This sclerite is the double sclerite furcasternum plus spinastermun fss0. Internally furca and spina are Joined. The distal ends of the furca fug are closely associated with the distal ends of the pleural apophyses p la of fig . 13. The spina of the mesosteroum hears one median and two pairs of lateral projections. Metasternum: The metastemum of Anahrus is divided into an anterior has!sternum ahsj and a posterior has!sternum ghsj. The anterior has!sternum ahs^ Ie a single prominent sclerite. The posterior hasisternum phs^ is marked hy the presence of two prominent hroad spines. The furcasternum fs^ is united with the posterior hasi sternum phs,. As in other Orthopteroids except Gryllohlatta the spina is lacking in the metastemum. Articulation of the wings; The tegmlna are articulated hy means of axillary sclerites. In fig. 14 their disposition and number may he seen as well as the disposition of other pteralla in the male thorax. The tegula tg is a small hairy scale-like Iohe at the anterior base of the tegmen. Between the tegula t£ and articulated with the Costa is the humeral plate hup. The f ir s t axillary sclerite lax in Anahrus is supported hy an anterior notal process which is hent under the main hody of the no turn so that a good portion of the axillary is hidden beneath the no turn also. The anterior end of the first axillary lax articulates with the complex of costal, subcostal, and radial veins which have anastamosed at the base. The second axillary 2ax is hinged mesally to the first axillary and the vein complex mentioned above is flexibly attached to its outer side. The second axillary 2ax may also he seen on the ventral side of the tegmen In fig. 13 where It articulated with the me so thoracic wing process wp^. The third axillary 3ax, "because of the centralization and merging of most of the important longitudinal veins of the tegmen represents in Anahrus a fusion of the third axillary and the two median plates which are usually hasad of the Media, Cuhitus, and first Anal vein.. The remaining tegmen articulation represents an interesting intermediate stage. . It is generally considered that the fourth axillary is a strongly sclerotlzed portion of the posterior notal process which has "become separated from the latter. The posterior apex of the third axillary articulates with the fourth axillary when it is present and with the posterior notal process when the fourth axillary is not present. In Anahrus an intermediate condition exists. The eclerite labelled Uax in fig. lU is separated from the main part of the posterior no turn "by a thinly sclerotized area which is not, strictly speaking, membranous. The sclerite labelled Uax may therefore he considered to be a part of the posterior notal process. Since it is more highly sclerotized than the rest of the posterior notal process and is fused with the posterior apex of the first axillary lax it is here considered to he an axillary Uax. The fourth axillary sclerite Uax articulates with the third axillary sclerite 3 ax. ; In the female Anahrus the tegmen is more reduced and shows an even more strongly fused group of axillarlee. All are apparently present in a less sclerotized state than in the male. Wings; I t can he seen in figs. 22 and 2] the tegmlna of the sexes differ. The tegmen of the male is larger. In this sex the Costa, -2 4 - Sa'bcosta, and Eadlus are present together as large ridge with the several veins composing suh-rldges. Very little other venation Is recognizable because the tegmen Is so atrophied. The male Anabrus strldulates by means of the tegmlna. As In many other strldulatory Insects the left tegmen folds over the right. Both tegmlna bear a flle-llke vein on the ventral surface. Strldulation Is accomplished when the tegmlna are vibrated, the file on the ventral surface of the left tegmen being scraped on the veins near the posterodorsal margin of the right tegmen. The right tegmen Is less highly sclerotized than the left. The median cell in the right tegmen is almost hyaline. The female tegmlna are shorter and thicker than those of the male. Thqy cannot be folded over each other. All that remains of the venation in this sex is the presence of four longitudinal ridges in a homologous position to the ridges on the male tegmen. The female has no means of stridulation. All that remains of the wings in both sexes is a membranous pouch Wj of figs. 13 and 14.

' ' "Lias

Although the legs could have been considered in the discussion of the pleural areas, they are here discussed together for convenience and ease of comparison. The pro thoracic leg may be seen in la te ra l view in Hg. 12 and Its basal articulation may be seen in figs. 13 and 18. In fig. 13 the coxa Cx1 is seen to have two means of articulation. The first is the pleural coxal process (a projection of the pleuron); the second is the trochantin tn^. The coxa cx of fig . 12 is rather broad. It bears a basal border the basicoxlte box which is set off from the main -2 5 - d lstal portion of the coxa by a suture (the basicostal suture). Bie basicoxite box in the foreleg of Anabrus bears one small fronto-lateral process and two meeal knob-like processes which are probably sensory in nature. The more lateral striated process may be seen in fig. 12. The mesal knob­ like processes bear tiny setae and may be seen in fig. 13 where the coxa

Cxl has been pushed rearward for purposes of illustration. The coxa bears one very large spine and numerous small setae. The main body of the coxa bears a small invagination (indicated by the dark pit in fig. 12) which is used for muscle connection. The coxa articulates with the trochanter tr by means of two fulcral points k, k which are seen best in fig. 13. Near the fulcral points the coxa is strengthened by internal ridges which are represented externally by sutures which cut off small sclerites from the main coxal walls. The coxa and trochanter are connected loosely by membrane. The trochanter tr and femur fe are joined firmly. B0th bear tiny setae. The femur fe of fig . 12 is ridged and fla t beneath. The mesal

■ ■ -'v - . - ridge of the femur bears several spines. Both la te ra l and mesal ridges usually bear a pair of small apical spines. The tibia ti_ is quadrate- cylindrical in cross section and of uniform thickness. The under side is 'i ** ■ ' ' - , somewhat flattened. Bie tibia tl bears a variable number of spurs. Bie usual arrangement is six ventral pairs, a laterodorsal row of five, and two or three on the medio dorsal surface. Near the base of the tibia ti of fig. 12 there may be seen a s l i t labelled aa. This s li t is matched on the mesal side by another slit. The two together comprise the auditory apparatus. Below the auditory apparatus aa there is a pair of small impressions one of which may be seen in fig. 12. Bie impressions are —26— deeper than faint tlhlal grooves shlch lead into them. The tarsus tar is four-segmented. The four segments are loosely joined and In fig. 12 have "been pulled apart to show their articulation to tetter advantage. The first tarsal segment is the longest and broadest; the fourth Is almost as long and is the most slender. The third tarsal segment is distinctly tiloted. Hg. 11 is a ventral view of the pretar sue of the foreleg. The pretarsus is attached to the fourth tarsal segment ta^. The ungoitractor plate utr when pulled by the tendon ten moves the unguis. Mesothoraclc leg; As in the foreleg the coxa cxg of figs. 13 and 16 articulates on a pleural coxal process and on the trochantin tn . —2 Like the first trochantin, the trochantin tn^ is rather hoot-like in shape. Its basal end articulates with the pi ear on at the terminus of the suture which divides the episternum eps^ into two p arts, and thus is closely associated with the posterior end of the precoxale prcxg. The membrane between the base of the coxa and the trochantin is marked by a narrow lin e- like sclerotization which delimits the inner attachment of the basicoxite hex and is indicated in fig . IJ by a lig&t dotted lin e. The basicoxite bex bears knob-like processes as in the foreleg. The pleural articular socket pas of fig. 16 articulates with the pleuron and divides the basicoxite into two parts. The posterior portion of the basicoxite is the meron mer. The trochanter tr articulates loosely with the coxa at two points. The trochanter has an Internalbgsicosta (represented by an external suture) which gives it a marginal sclerite. This proximal sclerite bears a small setae-bearing process similar to the areas present on the basicoxite. The trochanter tr and femur fe are Joined firmly. The femur is grooved beneath and bears a variable number of spines. The tibia ti is —27— shaped very much like the tihia of the foreleg and hears a variable number of spurs. The four-segmented tarsus tar Is attached to the tibia and bears the claws or ungues ung. Metathoraclc leg: A. lateral view of the hind leg may be seen in fig. 15. The hind leg is very large and is not drawn to the scale of the other legs for this reason. The coxa cx is marked by a suture on its poBteroventral side. Posteroventral views of th is and the other two coxae may be seen in fig. 18. In most respects the coxa is very much like that of the mesothoracic leg. The trochanter tr is very small and when not pulled out as in fig. 15 can hardly be seen. The trochanter is joined firmly to the femur fe. At the base of the femur a basicostal suture separates a marginal sclerite from the remainder of this leg segment. The femur bears a variable number of spines. The tibia ti bears numerous spihes and spurs. The pulvillus of the first tarsal segment is divided to form plantulae pin. -2 8 -

ABDcam

The abdomen of Anabras la essentially sim ilar to those of other . Walker (1919) discussed female terminal abdominal structures of Orthopteroids in a manner which affords easy comparison with homologous structures in the Mormon cricket. Snodgrass (1937) stated that Angbrus and other Decticinae exhibit some important phallic modification. Abdominal segments: The abdomen of Anabrus is rather cylindrical in shape. As shown in fig . 19 there are ten abdominal terg ites t^ 1Q, and nine stemites S1^ in the male. The female as shown in fig. 20 has ten abdominal tergites and eight stern ltes. In both sexes the membranes between the terg ites are almost as wide as the terg ites themselves. Normally most of this membrane is hidden in the telescoping of the abdomi­ nal segments. The sternum, however, does not reveal a sim ilar equality of sclerite and membrane. Therefore, i f the abdomen of Anabrus were drawn out fully it would appear quite like a semi-circle. The sternltes are very small and the membranous pleural area veiy large. The membranous pleural area is composed of dorsal, pleural, and ventral membrane. The tergites and stem ites are d istin ct.

There are eight pairs of abdominal spiracles 8£ in ^ frbrua' n i &re located in the membrane. An abdominal spiracle consists of two small sclerites which guard the opening to the trachea.

TERMINAL STRUCTURES OE mat.-b

Tergites; Starting with the eighth tergite tg of fig. 19 the tergites are smaller than those preceding it. Except for a tiny median -2 9 - dorsal area the anterior border of the tenth tergite t^ is almost entirely hidden from external view both by the posterior edge of the ninth tergite and. by membrane. The tenth tergite t^ presents a second­ ary modification. The median portion is of a membranous nature as shown in figs. 19 and 21. Sternltest The ninth stemlte s^ of figs. 19 and 21 is larger than the other stemites. This stern!te is the subgenital plate. It is divided transversely by a suture. The posterior portion of the ninth stemlte bears styli sty. In primitive insects such as the styli stg are borne by coxites. The ninth stemlte in Anabrus is considered, therefore, to bear united ninth coxites. Gurney (1936) pointed out that styli are not present in Ceuthophilus but are present in Bhaphidophora, Neoconocephalus, and Scudderla. Cercus? The male cercus is broad unsegmented, hooked apically and with a tooth directed mesally. Cowan (1929) used the cercus to identify the instars of Anabrus simplex. Gumey (1939) pointed out that the size and angle at which the tooth projects from the main body of the cercus may be used to separate A. simplex and longipes from cerclata since in the latter the inner tooth is large and projects at right angles. Anal sclerltes: About the anal opening a of fig. 21 are three sclerites. The suprarenal plate sap is often called the epiproct by systematists and was so called by Snodgrass (1937)• However, the former term was applied to the tenth terg ite by Crampton (1929, 1931) as Gurney (1936) pointed out. On each side of the anal opening a and below the supra-anal plate sap are the paraprocts ppt which are well defined -3 0 - sclerltes in Ana~brus. Ptola: Snodgrass (1937) discussed the penis of Anahrus simplex. The tettigonioid type of phallic structure hears in a modified form the three pairs of phallic lohes usually present in the Orthoptera. The lateral phallic Iohe Igl may he seen in fig. 19. Beneath the lateral phallic Iohe the posterior edge of the ventral phallic Iohe vl may he seen. The dorsal phallic Iohe is hidden internally and cannot he seen in fig. 19. It divides the phallic cavity in tiro acting as the floor of the upper cavity. The ventral phallic Iohe is the floor of a ventral cavity or spermatophore sac. The sclerotic arms of the phallus rest upon the top of the dorsal phallic lohe. ,

TSBMIKAL STBUCTtJBB 07 IBiALB

general features: The most marked differences from the abdominal sc le ritea of the male are seen starting at the eighth segment. The eighth and ninth tergites tg and t^ of fig. 20.differ in shape from the homologous male tergites. The tenth tergite t is rather similar to the tenth tergite of the male. There are only eight complete abdominal sternites in the female. The valvifer vf is a part of the ninth abdominal stern ite. The eighth abdominal sternite Sg articulates with the lower edge of the eighth tergite t^. The cercus ce of fig. 20 is slender and not broad and hook-like as that of the male shown in fig. 19. The supra-anal plate sap and paraprocts ppt are similar to those of the male. Ventral valves? The valves of the adult female Anahrus fit together tightly to form a sword-like ovipositor which is as long as the -3 1 - abdomen. The ventral valve vv of fig, 20 la fused at Its "base with the taslvalvula hv. The valvifer vf is a small sclerite to which the dorsoproxlmal edge of the ventral valve vv, and the dorsal valve dv are attached. The ventral valve hears a membrane on the proximal third of i t s mesal surface. Dorsal valves: The dorsal valve dv is broader than the ventral valve and like it is attached to the valvifer vf. The dorsal valve bears two internal apophyses, the superior apophysis sup and the inferior apophysis ia, for tendon attachment. Inner valves; The inner valve Iv of fig. 20 fits into the dorsal and ventral valves. The ramus r is an arm of the ventral valve Tqr which i t is connected to the body. The pons valvorum gv is a bridge connecting the two inner valves. The inner valves are attached dorsally to the superior intervalvula si and vent rally to the inferior interval vula inv. -3 2 -

ABBESVIATIONS MD LlTTlBINa QN PLATS HfflJBES a anal opening es epistomal suture auditory apparatus esp endostlpital process at3 anterior Lasietenmm est endostipes acs antecostal suture et extensor tehd(m an an term ale cu eutentorium or Lody of tentorium ant antenna asm anterior arms of suLmentum f frons atg acrotergite, pretergite fas fastigium ax axillary sclerite fee frontoclypeal suture axe axillary cord fe femur L Lasimaxillary memLrane tp frontal pit La Lasalare fs Aircastemum Lc Lasicardo f ss Aircastemum + spinastemum Lex Lasicoxite f t flexor tendon Lg Lasigalea Ai Airca Lgl Lasiglossa Aip Aircal pit LI Lasillngua Lm suLgena, LaslmandiLulare ga gnathapex Lmm LaslmandiLular memLrane ge gena Lr Lrustia gg glossiger Ls Lasisternum gi ginglymus Lu Luttressed area gl glossa Lv . Lasivalvula gn gnathite gp gular pit c clypeus gs gnathal suture or impress c da car do suture ce cercus h hypocondyle or gnathocondyle cp cardoprocess hypopharynx cs coronal suture hup humeral plate ctn cardotendon cx coxa ia inferior apophysis cxc coxal cavity it inter to rma Inv position of inferior intervalvula d articulatory process of Lasicardo Iv inner valve dc disticardo dcs dorsal cervical sclerite k Ailcral point of leg segment dg dlstigalea dl dlstilingua I lacinia dv dorsal valve la IaLrum IL long Lrachymere e compound eye Ic laterocervicale ec endocardo Id laciniadentes ep extensor prominence II IaLial stipites eps episternum II lingualora epm epimeron Ip IaLial palpus eg endognath Ipl lateral phallic IoLes III lacinula -3 3 - m mol a ptg posttergite md mandible pv pons Yalvorum mer meron mn men turn r ramus of inner valve men mesonotum mp maxillary palpus s stipes mtn metanotum Bi_g abdominal stem ite* sa subalare nf neural foramen sap suprarenal plate sb short brachymeres occ occipital condyle sc scape ocf occipital foramen scl s cut ellum set scutum p posterior tentorial arch sd slender dolichomeres par parietal si position of superior intervalvula pas pleural articu lar sock (of coxa) si suprallngua, dorsolingua pbs posterior has!sternum sm submentum pgs postgenal suture smm submental membrane pd pedicel sp spiracle pf pal&lfer spi ^pina pg palpiger spp spinal pit pga postgenal acetabulium ss spinasternunu <. pge poatgena st supratentorium pgl paraglossa stcs stemacostal suture pgs postgenal suture sty stylus ph prephragma sup superior apophysis pi postlingua or linguatendoh pla pleural apophysis ti_ioabdominal tergite pin plan tula tai| dlsti tarsus plr pleural ridge tar tarsus pn pronotum te tempua, temple po postocciput ten tendon poc parocciput or posterior arms of tes temporal suture tentorium tg tegula poe postepipharynx ti tib ia pos postoccipltal suture tn trochantin PP postgenal process to torma ppc pr^ectus tr trochanter ppd postpedicel, third ung unguis I'. . antennal segment utr unguitractir plate ppt pareproct pra prealare vc ventral cervical sclerite prex precoxale vl ventral phallic lobe pre preepipharynx w ventral valve ps parastipes vf valvifer Psc prescutum Pscl postscutellum Vg meeothoracic wing or tegmen pss paras tipi tal suture Wj metathoracic wing pouch pet parastorn!urn pt pretentorium or anterior arms of tentorium -34- Aaabrus simplex Plate I

Iig. I. Frontal view of the head. Fig. 2. Posterior view of back of head. Hg. 3* Antenna. Hg. 4. Posterior view of dextral mandible. Hg. 5« Anterior view of tentorium and neighboring parts. Hg. 6. Inner surface of cardo and stipes. Hg. 7. Inner or buccal view of labrum and clypeus. Hg. 8. Anterior view of gloseae and paraglossae. Hg. 9. Anterior view of laclnla and galea. Hg. 10. Lateral view of hypopharynx and upper and lower lip , with most of head capsule removed. -3 5 - plats I

IpH Hj I K /Tl / S i

Up. 3

M Iii -3 6 - Anabrus simplex Plate II rig. n . Ventral view of pretarsus of sinlstral foreleg. Hg. 12. la te ra l view of foreleg. Hg. 13. Lateral view of thorax. Hg. 14. Dorsal view of male pterothorax.

Hg. 15. Lateral view of rear leg. Hg. 16. Lateral view of mesothoraclc leg. Hg. 17. Lateral view of base of rear tib ia . Hg. 18. Ventral view of thorax,thorax.Ventral -37-

PLATE II

f -3 8 - Anabras simplex Plate III

Hg. 19. la te ra l view of adult male abdominal scleritee. Hg. so. Lateral view of adult female terminal eclerites. Hg. SI. Dorsoposterior view of adult male terminal sclerltes. Hg. 22. Female tegmen. Hg. 23. Male tegnen. -3 9 -

plate h i

F > .19

R f. 20 n F '21

R f 23 -Uo- S e c tio n I I I THS PBEBTBATION OP SODIUM AESSNITS TEEOUOS THB BXDSKSLBTGN REVIEW OP IITEEATUEE

Sodium arsenite has "been used both as a stomach and a contact poison. I t was not u n til 1923» however, that reference was made concern­ ing its possibilities in the latter method of killing insects. Previous to that year its efficiency as a stomach poison especially in baits was ? well known. Mally (1923) found that sodium arsenite when applied by means of hand bellows as a dust to the antennae of insects killed them even though i t was not Ingested.

Granovsky (1926) summarized the studies of several Russian scien tists. Sovdarg, one of the investigators, dusted and sprayed migratory with disodium acid arsenite (HaH AsOj)* and dlsodium acid arsenate (Ha2H AsOl4). Death occurred even thou^i the insects were given no opportunity to ingest the poison. Sovdarg pointed out that the spray acted upon the insects more rapidly than the dust and that if humidity were higher the arsenicala reacted more rapidly.

Granovsky (1926) noted that grasshoppers which had crawled through poison bait in which sodium arsenite was an ingredient often were found with the ventral posterior thorax and anterior abdomen in a disintegrated condition. Other parts of the body showed no signs of Injury * Noting the strength of the insecticide this author suggested the use of hydrated lime as a diluent. Shotwell and Cowan (1928) were first to test sodium arsenite (in the form of spray as well as dust) on the Mormon cricket. In tests on this

*- Probably Ha2H AsOj. insect and the lesser migratory , Melanoplns mexl caaus (Sanssnre), excellent results were obtained as far as 200 feet from the point of application. The poison was also effective when used as a barrier. These workers reported injurious action by the insecticide on several plants.

Cowan (1929) and Cowan and McCampbell (1929) noted that sodium and calcium arsenites in combination with hydrated lime are very effective as a means of controlling the Mormon cricket in all instars. Hot only did mortality remain hibut crops could be better protected by the use of such a diluent.

Zing and Rutledge (1932) stated that irregular results were obtained iAen a cloud of sodium arsenite dust was blown through a cage containing Locusta migratoriodes (Rch. and Zrm.). X series of experiments were carried on by these authors consisting of applications of dust to several parts of the locusts' anatomy. Ho ill effects were observed after two days. In another experiment the locusts were allowed to flutter in a cloud of dust and ingestion was prohibited. These locusts died and since arsenic was recovered from dissected tracheae the authors conclude that sodium arsenite probably has the tracheal system as its point of penetration. O'Kane and Olover (1935) placed arsenic-containing wax cells on the body of Perlplaneta americana (I.). Arsenic was recovered from vital internal organs, proving that penetration took place throng the integument. Both sodium arsenite and arsenlous acid penetrated, possibly with the aid of a surface fluid. Paralysis did not result from use of the arsenic.

Schweiss and Burge (1935) reported that sodium arsenite and -4 2 - Iioe, in combination, set uplaa irritation which is followed "by cleaning of the affected parts and subsequent ingestion of the poison. Olover (1936) • using a wax cell on Periplaneta aaerlcana, found that both arsenious oxide and sodium areenite penetrated the Integument. Sodium areenite was found to penetrate the more rapidly of the two. At high concentrations arsenic was recovered in all tissues and was voided through the digestive tract. Concentration of arsenic in the roach varied with the area of the cell. - . - Hastings and pepper (1939) reported on certain inert diluents used in conjunction with sodium areenite on the Mormon cricket. The insecticide was found to be both a contact and a stomach .poison. The point of 50^ mortality was reached earlier at higher temperatures. Adults varied more with temperature changes than did the nymphs in relation to the 50^ mortality point.

PBOCBIXJHS

The procedure adopted in this study may be divided into three parts: (I) the general handling of crickets* (2) the dusting of crickets with sodium areenite to discover whether some parts of the exoskeleton are more susceptible to penetration than other parts, and ()X the chemical analysis of the crickets after death to determine whether a relation exists between the amount of arsenious acid recovered, the time for 50^6 mortality, and the exoskeletal area treated. I. General treatment: During the study crickets were collected from the Infested areas south of Billings. Collections were made several times and the collections of three dates were used. This was made necessary "by the fact that adult crickets will not remain in good health when held in captivity. After collection the crickets were brought to Bozmmn and placed in a cage out of doors. During th is period they were fed with a lfa lfa , clover, and dandelion plants. Apparently normal crickets were then brought indoors and kept in a small cage within a temperature cabinet where the temperature remained constant at 27*0. and the humidity remained constant at approximately 53#» The crickets remained in the temperature cabinet for about 36 hours before being treated with the insecticide. During this period the Insects were fed regularly but they were not fed after the application of the dust.

II. The dusting of the crickets:

Since preferential penetration (of the same material) through different exoskeletal areas was one of the objects of the study it was decided to dust certain parts of the exo skeleton with chemically pure l|l meta sodium arsenite and leave other parts free of the poison. Because Anabrus simplex is a large and active insect it was recognized that merely placing the poison upon the desired locality would insure neither that the poison would remain on that part of the body, nor that it would not be ingested after cleaning with the mouthparts. In order to insure more exactness in these matters the crickets were (I) fitted with an appliance to prevent ingestion, and (2) a means of localizing the poison was perfected. The cricket was prevented from ingesting the poison by the use of a "collar" of the type used by Hastings and Pepper (1939). The "collar" ♦-Baker’s C.P. meta sodium arsenite (HaAsOg). when fitted over the head of the cricket prevented cleaning of the dusted areas ty mouthparts# Local!zation of the poison to the area to which i t was applied was difficult. Since the insect could move even with the collar in place, and would twist its body, the wax cell method as used by O1Kane and Olover (1935) was found impractical for general use on body areas of the Mormon cricket. It was decided, therefore, to develop a thin coating of some material which could be placed on the areas immediately adjacent to those areas dusted. Some thirty glues and plastics were tested and rejected. It was found that water soluble glues usually did not adhere to the body of the cricket or were not ample protection. Glues with a powerful organic solvent usually killed or injured the insects Several of these glues or plastics and several waxes necessitated use of high temperatures during application. The protective coating used in most cases in this experiment was a paraffin melting at 38° to UO0 C. Because application in quantity at this temperature could not but be either injurious or upsetting to the normal physiological activity of the cricket, the paraffin was applied by means of a melting apparatus. A group of electric sockets were connected in parallel. To complete the circuit, two thin wires (Alumel 27) were used. The wires were connected by twisting together and soldering, and their ends were filed to a fine, needle-like point. Close to their point of connection each of the wires was sheathed in a narrow glass tube six inches in length. The glass tubes were fused and then taped together. The grade of wire used offered enough resistance to the electric current to result in a rise in temperature which could be controlled by the -45- number of lamps and their wattage placed In the sockets. The warm pointed Mid of the melting pencil was dipped Into the solid paraffin and then "brought close to the ezoskeletal portion to be coated. Since the point was very fine the paraffin could be applied in very minute quantities which would solidify immediately after contact with the cricket. Throughout the entire experiment care was taken not to heat either the wax or the pencil to a temperature which would be harmful to the cricket. Application of paraffin was done in each case with the aid of a hand lens. After application and careful testing to see if the cricket was "apparently normal", the insect was dusted on the exposed portion by means of a small brush containing several fine bristles. The collar referred to above was then adjusted and an identification number written on it*. Crickets that had been so treated were placed in 5-inch petrie dishes that had been so divided by cardboard partitions as to allow equal spaces for four crickets. Ihen the four crickets were in their places the petrie dish was covered with netting to prevent their escape, and placed in the same temperature cabinet from which they had been taken prior to dusting. Nine dusting experiments (series I to IX) were carried out. In table I the series are lis te d by number and th e ir treatment with C.P. meta sodium arsenite (Na AsOj (without diluent) is indicated.

•-Check lots of undusted crickets were kept under the same conditions. The check lo ts consisted of one unwaxed group wearing collars, one waxed group wearing collars, and a small group that had not been handled. In no case was there any mortality in the check lots before 100$ mortality had been reached in 4he dusted group. -46-

Table I.—Application of sodium arsenlte to various parts of exoskeleton and disposition of paraffin Series Sodium arsenlte dust applied Paraffin applied to: Type of No. to; paraffin I dorsal abdominal membranes tergltes before and $8-40* C. I I to V III inclusive behind the membranes II abdominal terg ltes II to membranes before and 38-40*0. + VII inclusive behind the tergltes small amount of beeswax to make i t secur III ventral abdominal membranes ventral abdominal 38-40» C. II to VIII inclusive plates IV ventral abdominal plates ventral abdominal 38-4o* 0. I I to VII Inclusive membranes V la te ra l membranes of border of terg ltes 38-40*C. abdomen above and border of abdomen immediately below pleural membranes, also femora of posterior legs VI pronotal shield border of pronotal 38-40*0. shield, also femora of first 2 pairs of legs

VII membrane beneath pronotal w * - - shield

VIII thoracic pleura not femora of la st two 38-4o* c. including propleura pairs of legs IZ tarsi of all the legs tibiae of legs 38-4o»c. -47- It may be of interest to note the method employed for Judging the crickets to be normal or abnormal and the method of determining mortality. It was found that an apparently normal cricket recently taken from the field reacts in a characteristic manner to certain stimuli. A sudden movement toward i t by an object (such as a pencil) two or three inches from its eyes usually results in a rapid retreat or a hasty back­ ward movement accompanied by continued playing of the antennae. A normal cricket also can climb to the top of the cage and can easily climb a cardboard held at a 45» angle. I t w ill, moreover, immediately regain its feet if turned on its back. Lack of the last reaction or more than one of the preceding was taken as a sign of abnormality. Observations of Mormon crickets dusted with sodium arsenite revealed that their a c tiv ities and reactions underwent certain and definite change in a rather regular order. Perhaps the first sign of abnormality is a general sluggishness and slowing up of some of the regular responses. This may be called "subnormality". The second stage is the evidently great difficulty encountered in returning to the normal position from an inverted one. This may be called "slight loss of coordination". The third stage is indicated by inability to recover the upright position and may be referred to as "loss of coordination". The fourth stage which may be called "complete loss of coordination" may be recognized as that point in which the cricket will respond to stimuli by a mere twitching and little, if any, organized response. Death was taken to be the point at which crickets showed no movement and no v isib le reaction to prodding with a dissecting needle. -46- Throughout the study crickets were used only If they showed the "normal reactions". Check lo ts of crickets underwent the same te sts. After "being dusted and placed In the temperature cabinet the crickets were examined at hourly Intervals and their condition noted. Since each cricket was numbered Its condition could be followed from hour to hour and noted on a record sheet of the sample type shown In table I I. below. In this table conditions are indicated by symbols*. Table I I .—Sample data sheet. ______Series I Cricket ■ I Hours sifter dusting number I 2 3 4 p b 8 9 10 11 12 13 14 15 1& i t I AN SH SLC LC CLC D 2 AH SH SLC LC CLC D 3 AH SN SLC LC CLC D • 4 AH SN SLC LC CLC D 5 AH SN SLC LC CLC D 6 AH SN SLC LC CLC D ♦-Definition of abbreviations AH - apparently normal SH - subnormal SLC - slight loss of coordination LC - loss of coordination CLC - complete loss of coordination D - dead

III. Quantitative determination of sodium arsenlte; When the crickets were adjudged dead they were taken from the petrie dish and washed carefully to remove the sodium arsenlte which re­ mained on the outer surface. The crickets (with collars still In place) were then dried in an oven at 85°C. The insects were divided Into ten groups of five each according to the order in point of time in which they died. Thus the first five to die were analyzed as a group, group I of series I; the second five to die, group 2 of series I were analyzed as a group also. In most cases the f irs t two groups to die (group I and group 2) and the last two groups to die

(group 9 and group 10) were taken for analysis in order that the extremes might he tested. When more than five crickets died in the same hour five crickets for the group were chosen at random from those having died that hour. In some cases because of technical difficulties or distribution of mortality, groups 3 and U or 7 and 8 were taken in preference to the

extreme groups. In one series seven of the ten groups were taken in order

to compare better the time of mortality in the groups with the amount of

arsenious oxide determined. The method of analysis used was a modification

of the Qutzelt method, as given in A.O.A.C., fifth edition (igho).

MTBCT OF IXJSTINQ THE ABDOMffl WITH SODIUM AHSfflITS

A. Effect of Dusting the Dorsum

Adult crickets collected at the same time were divided into two

groups. The first series was dusted with sodium arsenite on membranes

II to VIII inclusive of the dorsal abdomen. The second series was dusted

on the tergites II to VII inclusive of the abdomen. It was intended by

this means to determine whether or not the tergites or membranes of the

dorsal abdomen permitted greater penetration or resulted in a more rapid

mortality. One more membrane was dusted than the number of tergites

in order to have a more equal total area. It may be noted in passing that

the membranes are not very much smaller than the tergites. The greatest

difference lies in amount of exposed surface since the membranes are

folded in beneath the sclerotized areas. In dusting the membranes the

abdomen of the cricket was bent gently so that the entire membranes could -5 0 - t# dusted. , In a comparison of exoskeletal areas for the purpose of this study It is necessary to consider time required for reaction to the poison as well as quantity of penetration. The first two series revealed little time difference in passing through the stages shown "by poisoned crickets. Tables III, IV and V show the manner in which the series reached these stages. The time necessary to reach 50# mortality for series I and II may "be seen in figure 24. It will he seen readily from this figure that the differences are. merely a matter of minutes. In view of these facts it may he said that differences in speed of action are very small. In comparing the amount of penetration shown hy quantitative analysis two points were considered! (I) the possible existence of a relation between time of m ortality within a series and the amount of sodium arsenite that penetrated; (2) the possible existence of a relation between similar times of mortality in different series and the amount of sodium arsenite found in the crickets. In the first series the first and second groups of five and the last group of five to die were analysed by modified Qutseit method. From the second series the f ir s t and second and the ninth and tenth groups of five were selected for analysis, as outlined in the procedure above. Table VI shows the results of analysis. In the first series comparison of groups I, 2, and 10 show no definite relation between amount of penetration and the time of m ortality. In series II the first ten to die show about three per cent more arsenious oxide than do the last ten crickets to die. It would appear then that in each of the first two series (within the series) time of death and amount -5 1 - fable III.—Per cent loss of coordination fim e in hours I II I I I IV V TI VII VIII IX C1 C9 I 18 24 2 0 4 0 0.00 0 0.00 0 0 2 54 80 86 4 86 10 6.67 4 3.33 3 30 3 80 98 100 12 96 48 17.35 16 70.00 60 95 4 92 100 - 36 96 82 24.00 34 90.00 85 100 5 96 70 100 96 29.33 52 96.67 95 6 100 86 98 33.33 62 100 7 - 98 98 48.00 68 8 98 100 58.67 80 9 100 70.40 88 - 10 72.67 90 11 80.00 90 12 92 92 S 96 15 100 —^2— Table IV.—Per cent complete loss of coordination Time in hours I II III IV V VI VII VIII IX C1 Op I 4 0 0 0 I0 0 0.00 0 0.00 O 6 2 26 12 4 0 4 0 0.00 0 0.00 O 0 3 46 56 82 0 60 6 4.00 4 0.00 10 0 4 66 92 98 4 78. 26 10.67 16 36.67 4o 60 5 80 92 98 20 90 6s 18.67 30 63.33 65 85 6 84 100 100 42 96 ' 92 30.67 34 83.33 80 90 7 92 60 98 96 54.67 48 93.33 90 95 8 100 74 98 98 66.67 56 96.67 95 100 9 82 100 100 70.67 68 96.67 95 10 94 78.67 78 96.67 95 11 94 85.33 84 96.67 100 12 94 90.67 86 96.67 13 98 92.00 86 96.67 14 94 92.00 88 96.67 15 100 93*33 94 100.00 • 16 96.00 96 17 96.00 96 18 97.33 98 19 98.67 100 20 100.00 -5 3 -

Table V.—Per cent mortality

Time In hours I II III IV V VI VII VIII IX Ci G? I 0 0 0 0 0 0 0.00 0 0.00 0 0 2 2 0 0 0 0 0 0.00 0 0.00 0 5 3 12 0 2 0 4 0 0.00 0 0.00 0 20 U 16 8 4 2 14 2 0.00 0 0.00 o 50 5 22 14 18 :o 18 24 0.00 L 6 10.00 o 65 6 28 24 38 0 32 30 4.00 18 16.67 0 90 7 40 34 60 0 50 58 8.00 22 26.67 10 100 8 48 54 74 0 . 64 70 14.67 29 46.67 do 9 62 70 88 8 70 82 28.00 26 53.33 10 72 78 94 12 78 86 37.33 34 56.67 65 11 76 84 96 20 90 92 42.67 44 70.00 75 12 86 88 100 28 94 100 50.67 52 83.33 13 90 92 44 98 62.67 56 90.00 IU 94 96 54 68.00 93.33 15 98 98 64 72.00 66 97.67 16 98 100 66 77.33 80 100.00 95 17 100 74 84.00 82 95 18 78 100 88.00 86 95 19 78 90.67 88 100 20 84 94.67 88 21 90 94.67 90 22 98 96.00 92 23 100 97.33 92 24 100.00 98 I

PERCENT MORTALITY i. 4 Motlt cre f ds applc i in n tio lica p p a dust r fo curves ortality M 24. Fig. ------SERIES E 5ERIE5 I re I (boia tergi . ) s e it g r and e t membranes) (abdominal abdominal II orsal (d eries S I eries S I E N HOURS INTIME 54- 4 -5

-5 5 - o f sodium arsenlte that penetrated seem to have no direct relationship. In comparing series I and II for evidence of differences in rate of penetration, it will he seen that crickets dying in the same time in the two series cannot be significantly compared since, as has Just been shown, no relationship exists in a given series between time of death and amount of penetration. Comparison by averages of crickets in the two groups shows that series I absorbed .206 mg. of poison per gram of dry body welgjht while series II absorbed .228 mg. of poison. The differences here are not very significant because they are within the realm of experimental error.

B. Effect of Busting the Pleura and Venter of the Abdomen

Crickets that were collected from south of Billings on the same date were taken to Bozeman and handled as described in the procedure. In th is second batch of crickets three groups of f ifty crickets each were dusted on three different parts of the abdomen; the ventral membranes, the ventral plates, and the lateral membranes. Those series dusted on ventral and lateral membranes (series III and V) show a marked similarity in reaction. Iifty per cent of the crickets in both series reached first loss of coordination between the f ir s t and second hours after application. Fifty per cent in both series reached the point of complete loss of coordination between the second and th ird hours, and 50$6 mortality in the two series took place about one half hour apart, as shown in fig. 2$. Crickets in series IV were dusted on the ventral plates. This series took one of the longest of any in the study to reach fifty per cent mortality. The reason for this may be ascribed partially to the smaller PERCENT i. 5 Motlt cre f applc i n Seis III eries S in n tio lica p p a r fo curves ortality M 25. Fig. 0 ----- SERES 0 E IS H SERIES series boia membranes). abdominal H ve r admnl ebae) Seis IV eries S membranes), abdominal l tra en (v admnl tes), n seri (at l a r te (la V s ie r e s and , ) s e it n r e t s (abdominal 3 E s — y I E N HOURS INTIME 56- 6 -5

—57- area involved and the fact that the dust may he more easily claimed by gravity in this position. However, the latter reason should be applicable to series III (the series in which the ventral membranes were dusted) and this series required the least amount of time to reach the point of $0# mortality. It would appear then that the lateral and ventral membranes permit more rapid reaction both because of differences in area and qualities of the membrane. The quantitative analysis of crickets in each of the three series, as shown in table TI, reveals a minor trend toward greater penetration among crickets which lived longer within their own groups.

X comparison of time required for 50$ mortality in the three series, fig. 25, and average amount of penetration till death, table TI, shows again the lack of relationship between the two. Differences in the distance from vital organs as well as the size of the areas are very probably the explanation for the fact that crickets dusted on lateral abdominal membranes absorbed the most poison in almost the least time. The fact that the ventral membranes are close to the main nerve trunk might explain the fact that

a quick reaction was shown to the poison (which has been considered par­

tially a nerve tissue poison), but that penetration might not have been

especially great. The time for the first reaction to the poison may be

seen for all the series in table III. . Further reactions may be seen in

tables IT and T.

BFFBGT OF DUSTING THB THOBAX AND ITS APPENDAGES

From a batch of crickets collected on the same day four groups

of crickets were isolated and tested to determine the effect of sodium

arsenite on the thorax and its appendages. The four series consisted of -5 8 - Table VI.—Quantitative data on penetration

Group

2 45 117 )

307 ) 142 ) I I I 3 I

3 .15 2.8275 - .1400 . .080 .142 ) : 4 16 2.9939 .375 .075 .125 ) .162 5 17 2.5297 .750 .150 .296 ) 6 18 3.1015 .375 .075 .121 ) 7 19 - 2.7793 .375 .075 .135 ) - V I 24 2.7025 I.125 .225 .416 ) 2 25 2.9779 .750 .150 .252 ) .368 9 26 2.8086 1.050 .210 .374 ) 10 27 2.9034 1.250 .250 .431 ) VI I 28 1.6205 0.250 .050 .154 ) 2 29 1.853 .250 .050 .135 ) 8 30A 1.9625 .250 .050 .127 ) .159 9 30B I.S196 .250 .050 .137 , ) 10 31 2.0666 .175 .035 .085 ) VII I. 20 1.7434 0.375 . 075 .215 ) 2 21 2.06l6 .250 .050 .121 ) .128 9 23 2.0776 .175 .035 .084 ) 10 22 1.8752 .175 .035 .093; ) VIII 1 32 2.1941 0.375' .075 .171 ) . 2 33 . 1.8995 .400 .080 .211 ) .150 9 34 2.4401 .150 .030 .062 ) II I 26 2.4152 . 675 .135 . 279 ) 2 37 2.3394 .400 .080 .171 ) .218 7 38 2.3930 .500 .100 .209 ) 10 39 2.3217 .500 .100 .215 ) -5 9 - applications on the pronotal shield (series VII)« the sides of the thorax not including the propleura (series VIII), and the tarsi (series IX). The application of sodium arsenite on the pronotal shield was localized "by the use of paraffin as a thin edge around the shield. Paraffin was also placed on the tibia of those insects on which the tarsi were dusted and on the femora of those having the pleura dusted. Ho paraffin was used on those crickets which were treated with sodium arsenite on the membrane beneath the pronotal shield, , The mortality curves of those series on which applications were made on the membrane beneath the pronotal shield and on the thoracic pleura show a rather marked similarity. The points of 50$ mortality are only about twenty minutes apart, as may be seen in fig. 26. These two series are in sharp contrast with the series VI and IX, crickets dusted on the pronotal shield and on the tarsi. By looking at fig. 26 the midU point for the four curves may be noted. Series VI and IX are about two hours apart at the point of 50$ mortality. The reason most plausible for series IX to have a more flat mortality curve than VI may be the distance tarsi are found from vital centers. Careful examination of the pleura of the thorax and the membrane beneath the pronotal shield reveals a common factor. Both are smooth and offer fewer crevices and less opportunity for adhesion and subsequent penetration. The pronotal shield on the other hand supplies a wide" penetrable surface and therefore yielded an early 50$ mortality Comparison of the time required for 50$ mortality with the quantity of penetration (table VI) reveals that in the groups tested no PERCENT MORTALI i. 6 Motlt cre f s es V (rntl el ), ld ie h s (pronotal VI s ie r se r fo curves ortality M 26. Pig. • —- SERIES Vll -e e— e —o SERIES o IX o— ------SCRIES « SERIES • ST es VI ( eot rcc eura) ad eri IX s ie r se and ), a r u le ), p ld ie h oracic s th tero (p pronotal VIII beneath s (membrane ie r e VII s s ie r se . ) i s r a t ( I E N HOURS INTIME 6o- o -6

- S i - relation seemed to exist -"between the point of 50$ mortality and the relative amount of sodium arsenlte determined per unit of dry "body weight.

QWSBU j CONSIDERATIONS

Since the crickets were tested in groups which were collected at three different dates, the probability exists that all three groups differed from one another in many respects. Itor this reason the series have been compared only with other series which were collected at the same date.

Since it is of Interest, however, to compare all the groups with each other some "common denominator" is necessary. The factor that might be used for a tentative comparison In this case was the testing of all cricket groups with one type of application and then weighting that group with the value of its 50$ reaction point when compared with the value of the first group so tested. Bie series used as a test series was series II.

Table V reveals the time in hours for 50$ m ortality derived in the ordinary manner (taken from the mortality curves, figs. 2^-26). Series II was taken as a basis of comparison. In this series the tergltee of the abdomen were dusted and the point of 50$ m ortality, 7.7 hours considered as the comparison unit. Twenty crickets from each succeeding batch were dusted and treated exactly as was series II. Each 50$ reaction point

C1, C2 of tables III, IV, V thereafter could be welghted^according to the value obtained in comparison with the small group acting as a "common denominator". It must be pointed out that no attempt atj preciseness in comparison is claimed in this fashion, but that a general method of comparison may thus be drawn. By this means, if m ortality I8 considered, —62— series III, IV, and V might "be given a rating of 83$ strength of the first two series and the third collection "batch might "be rated 104$ in the same manner. The time for 50$ m ortality might then "be considered as in table VII. -62-

Table VII,— Time for 50^ mortality on a comparative basis Series Time for 5Qf> Adjusted time Ho. mortal!ty for 50$ mortality I 8.0 8.0 II 7.7 7.7 III 6.8 5.7 IV 13.8 11.6 V 7.4 6.2 VI 6.8 7.1 VII 12.4 12.9 VIII 12.0 12.5 IX 9.0 9.4 -64- COKGLUSIOHS

The most striking aspects of the morphology of Anahnxs are the modifications of the thorax. The mesothoracic spiracle presents an unusual, if not hitherto unknown, modification in insect anatomy. This spiracle may he of interest from the aspect of Mormon cricket control. The Mormon cricket shows a definite and orderly change in its reactions once penetration of sodium arsenite begins. It never recovers from any of the stages through which it passes. Inspection of tables III, IV, and V reveals that in general those series reaching the point of 50$ mortality also reached the points of 50$ la the several stages of reaction in a parallel manner. Time required for 50$ mortality and the amount of sodium arsenite that penetrates in that time apparently have little, if any, relationship. Membranes have, in general, a tendency to permit a greater speed of reaction. This is modified to a large extent by the proximity of the area to Important organs, the qualities aiding or hindering adhesion, the position of the area in regard to its action as a barrier to gravity, and the size of the area. Thus series I, III, V, and IX are either membranous or contain much membrane. They, therefore, showed early reactions to the poison and reach­ ed the point of 50$ mortality. Series VI, in which a large sclerotlzed area, the pronotum, was dusted, reacted slowly at f ir s t but reached the point of 50$ mortality almost as quickly as the speediest of the membranous areas. The smoothly membranous series, series VII, required one of the longest 50$ mortality points since it offered little opportunity for adhesion. The thoracic pleura and abdominal eteraites which are sclerotlzed. -6 5 - and vhlch are rather smooth, give little aid to adhesion, "both required a lengthy period to reach the point of 50$ mortality. Dusting of the abdominal terg ltes may have resulted in an early reaction because of the size of the areas and the proximity to the main circulatory system. - 6 6 -

1ITBBATUB3 CITED MD CONSULTED Association of Official Agricultural Chemists 19^0. Methods of Analysis. Association of O fficial Agricultural Chemists, Washington, D.C. Bales, I.W. 1936. Cricket control in Washington, Jour.Scon.l n t .29:916-918. Blatchley, W.S. 1920. Orthoptera Of America. The Nature Publishing Co., Indianapolis, Ind. 784 pp. 246 figs. Comstock, J.H. 1936. An Introduction to Entomology. The Comstock publishing Co., Ithaca, N.T. 1044 pp. 1228 figs. Comstock, J.H. and Kochi C. 1902. The skeleton of the head of insects. Am. Nat.36;13-45. Cowan, F.T. ^■929. Life history, habits, and control of the Mormon cricket. U.S.D.A. Tech. Bui. l6 l, 28 pp. 24 figs. Crampton, C.C. 1915' thoracic sclerites and systematic position of Grylloblatta caapodelform 13 Walker, a remarkable annectent “Orthopteroid" insect. Ent. News 26:337-350, I pi.

1916a. A comparative study of the maxillae of the Acrldldae (OedipinaeandTettiginae)l PhasmidaeandPhyllidae. Psyche 22:83-87. I pi.

19l6b. The lines of descent of the lower Pterygotan Insects, with notes on the relationships of the other forms. Bat. News 27:24b-258 , 297-307, I fig.

1917&. A phylogenetic study of the lateral head, neck, and prothoracic regions in some and lower Pteryeota. Bnt. News. 28:398-412, I pi.

1917b. A phylogenetic study of the terminal abdominal segoments and appendages in some female Apterygotan and lower Pterygotan Insects. Jour. N.T.Ent.Soc.2^:225-237. 2 pi. -6 7 -

1918a. A phylogenetic study of the terga and wing bases In lkbllds, Plecoptera, Dermaptera and Coleoptera. Psyche 2%:1, 4-12, I pi.

19181». A phylogenetic study of the terminal abdominal structures and genitalia of male lpterygota, Ephemerlds, Odonata, Plecoptera, Neuroptera, Orthoptera, and their allies. Bui. Brooklyn Ent. Soc. 1^:7, 49-68, 6 p i.

1918c. The thoracic sclerites of the grasshopper, Dlssosteira Carolina I. Ann. Ent. Soc. Am. 11,4. 147.^87 \ fig=.

1919. Notes on the phylogeny of the Orthoptera. Bit. News 25.: 42-48, 64-72, I fig.

1921. The sclerites of the head, and the mouthparts of certain immature and adult insects. Ann. Bit. Soc. Am. 14,65- 103. 7 p is. —

1923. A phylogenetic comparison of maxillae throughout the orders of insects. Jour. N. I. Ent. Soc. Tl:77-106, 6 p is. .

1925. The external anatomy of the head and abdomen of the roach, Perlplaneta americana. Psyche 12,195-220. I nla.

1926. A COBtparl son of the neck and pro thoracic sclerites throughout the orders of insects from the standpoint of phylogeny. Trans. Am. Ent. Soc. 52% 199-248, 8 p is.

1927a. The thoracic sclerites and wing bases of the roach, Periplaneta americana, and basal structures of the win»« of insects. Psyche 34:59-72, 3 pie.

19271). The abdominal structures of the Orthopterold family Grylloblattidae and the relationships of the group. Pan Pacific E n t.U5-I33. 1929. The terminal abdominal structures of female crickets compared throughout the orders from the standpoint of phylogeny. Jour. IT. Y. Ent. Soc. 37:453-496, 8 pie. . . . ?

1930. The head structures of the Orthopteraa Stenopelmatus - a contribution to the study of the external anatomy of Stenopelmatus. Pan Pacific Bnt. 6:97-110, 2 pie.

1932. A phylogenetic study of the head capsule in certain Orthopteroid, Psocoid, Hemipterold, and Holometabolous insects. Bui. Brooklyn Ent. Soc. 27:19-55« 5 p is.

193s. The structures called parameres in male insects. Bui. Brooklyn Bnt. Soc. 33:16-23. 1 p i. Diporte, E. M. 1919. The propleura and pronotal sulci of the Orthoptera. Can. Bnt. 51:147-153« 13 fig s. Eesig , E. 0. 1934. Insects of Western Worth America. MacMillan Book Co., New York. 1035 PP- 766 figs. Clover, L.C. 1936. On the penetration of certain arsenical compounds into the body of the American , Periplaneta americana I. Iowa State Jour. Sci. 11: 57- 59. Cranoveky, A. A. 1926. The control of grasshoppers by airplane dusting. Jour. Boon. Eat. 19:791-795. GkAA U O jf • JL* 1936. The external morphology and phylogenetic position of the woodland cave cricket (CeuthophiIus brevipes Scudder; Orthoptera: TettlgonlIdae). Jour. N. Y. Bat. Soc. 44:281-315, 2 pis.

1939. Aids to the identification of the Mormon and coulee crickets and their allies (Orthoptera; Tettlgonildae; G ryllacrididae). U.S.D.A. B479, 18 pp, 28 figs. Handlirsch, A.

1 9 2 5 . Geschlchte, Literatur, Technile, Palaontologie, Phylogenie und Systematik der Insekten. Schroder's Handbuch der Bntomologie, Jena, Band, 3» 1201 pp. 1040 fig s. —70— Mally, C. T. 1923» Arsenate of soda as a locust poison. Jour. Dept. Agr., Union of South Africa, 6:220-232. Newell, A. Cr, 1918. The comparative morphology of the genitalia of Insects. Ann. Ent. Soc. Am. 11:109-142. 14 p is. O1Kane, W. C. and Glover, L1C. 1936. Penetration of arsenic into insects. New Hantpshire Agr. Exp. Sta. Tech. Bui. 63, 8pp. Schweiss, G. C. and Burge, L.M. 1935» Mormon cricket control in Nevada. State Dept. Agr. Shotwell, B. L. and Cowan, P. T. 1928. Some preliminary notes on the use of sodium arsenite dusts and spray in the control of the Mormon cricket (A. simplex Said.) and the lesser migratory locust, M. Atlanis Biley. Jour. Econ. Ent. 21:222-230. “ Snodgrass, B. E. 1903. Notes on the internal anatomy of Peranahrus scahricollis (Thom.). Jour. N. I . Ent. Soc. U : 183-188, 2 p is.

1903. The anatomy of the Carolina Locust. Wash. Agr. Col., Pullman. 50 pp., 5 pis.

1907. A comparative study of the thorax in Orthoptera, Euplexcptera, and Coleoptera. Proc. Ent. Soc. Wash. 2.:95-108, 27 figs.

1909. The thorax of Insects and the articulation of the wings. Proc. U. S. Nat. Mus. 2§: 511-595 , 30 pis.

1927. Morphology and mechanism of the Insect thorax. Smithsonian Misc. Col. I?1-108, 44 figs.

1928. Morphology and evolution of the insect head and its appendages. Smithsonian Misc. Col. 81:158 pp., 57 fig s.

...... 1929. The thoracic mechanism of a grasshopper and its antecedents. Smithsonian Misc. Col. 82; 111 pp/, 54 figs. -7 1 -

1955* Principles of . McSraw-Hlll Book Co., N. Y. 667 pp., 319 figs.

1936. Morphology of the Insect ahd. I II . The male genitalia (including other than insects). Smithsonian Ml sc. Col. 25.: (14) 96 pp. 29 fig s.

1937» The male genitalia of Orthopteroid Insects. Smithsonian Misc. Col. 96:(5) 102 pp., 42 figs.

19140. The male genitalia of Hymenoptera. Smithsonian Mis6. Col. 22: (14) 86 pp., 33 pis. Turner, C. L. 1916. Breeding habits of the Orthoptera. Ann. Eat. Soc. Am. 2:117-155. Uvarovt B. P. 1928. Locusts and Grasshoppers. Iftn. Clowes and Sons, L td., London. 352 p p ., 118 p is. Vinal, S. C. 1919» The respiratory system of the Carolina Locust (DLssosteria Carolina L.). Jour. N. Y. Bnt. Soc. 27:19-22, lb figs. Walker, E. M. 1919a. On the male and immature state of Grylloblatta campodelformis Walker. Can. Bat. 51:131-139, I 3 figs.

19191». The terminal abdominal structures of orthopteroid Insects; a phylogenetic study. Pt. I. Ann. Bnt. Soc. Am. 12;267-316.

1922. The terminal structures of orthopteroid insects; a phylogenetic study. Pt. II. Ann. Bit. Soc. Am.15:1-89.

1931. On the anatomy of Grylloblatta campodelformis Walker. I. Bxeskeleton and musculature of the head. Ann. Bit. Soc. Am. 24.519-536.

1933« On the anatomy of Grylloblatta campodelformis Walker. 2. Comparisons of head with those of other orthopteroid insects. Ann. Bnt. Soc. Am. 26:309-344. 19)8. On the anatomy of Sryllohlatta campodelformlg Walker. 3* Ann. Bnt. Soc. Am. 31:588-640.

W igglesw orth, V. B. 1939. The Principles of Insect Physiology. B. P. Dutton Co., H. Y. 434 pp., 316 fig s.

Yuaaa, E.E . 1920. The anatomy of the head and mouthparta of Orthoptera and Buplexoptera. Jour. Morph. 33:251-287, 163 figs. N578 Do Not Circulate T15e