PROCEEDIN GS, 1929 9 'The Dermaptera of Canada B y E. R. B UCK ELL, Dominion E11 tomological L aboratory, Vernon, B. C. Order DERMAPTERA.l The Earwigs. 181S-Dermaptera Leach, Edin. E ncycl. I X . 1829-Forficulidae St eph. , Cat. Brit. [ns. Vol. 1, p. 299. 183 1-Euplekoptera W est ",., Zool. J our, No. X I X . 1834--Forficulina Newm., E nt. Mag . W alker , Vol. 2, p. 424. 1838-Dennatoptera Burm. , Hanb. E nt., V ol. 2, p. 743. 1839-Euplexoptera \ Vest\\· .. I ntrod. Class. Ins., Vol. 1, p. 398. 1882- Forficularia Brunner. P1"Od r. E ur. Orth., p. 1. 1893- Forficuloidea Boli var. Hev. BioI. Nord. Fr. Vol. 5. p. 477. (Other names. \\'hich haye been occassiona ll y used, it is unnecessary to quot e. ) Due perhaps t u t he fact tha t in t hem selves t he ea1"\\"i g s form a \\'ell ­ defin ed natu ra l g r uup. t her e has been som e considerable difference of opinion a m ongst entom olngist s \\·it h r egard to t heir rela t ionship to (l ther insect s. M a ny ~ p e c i cs in generill appea rance a r e \'er y like beetles. a nd Burr" spea k s u f Labia minor L innaeus as Ay in g \\" it h a nd mim ic ki ng certain B rilc hely tra. ,,' c a rc not. thcr efore. surprised t(l fi nd that Li n­ na eu s classed t hCll1 \\'it h t he Cu1cuptera ( Ll1 ca~. )" T hi s sma ll group u i insecb. consist ing o f some fi\'e hu ndred sp ec i e ~ . mostl y t ropica l or se l11i -tropicil 1. Jlu pularl.\' call ed ea r \\'ig " il nd k no \\' n ill scic ntific te rl11i ll o l( )g,\' a s DCrlll a pl era. ,Euplexopter il o r r orflc ulidae. is at the prescnt ti nle \1 s \1 a ll\' .~· il"l' n ordina l ra ll k.' S O I11 C s\'stellJ <l ti sts. hu \\'ey e r, consid er tl1 ;) t t he\' ,l1l1 ul cl C() lht ii ll (, a sub-order" ('r il i;llllih"" lJf the orde r Orlhnptcra . ' [)e rtll"ptcra: <1l'I'Illa. ,kill: ptncili. a \\illg. l D l' Ccer p r opO'l'<1 t lii, na1lll' for tli .. \\'11<)\' pi lh l' ()rt h nptl'l';\' " \ I"lll. !'ulIr 'el'\. ;1 I·Hi ,!. d ·I 'I'.·' I. ( htli. \ ' ,,1 I II. I7/.U " Illl rr. Ellt. n ee. X I. :\0. 2. I XI) '). "r.tlca,;. JLit. Urtl\. p. 7. 19.20. '\Ior,c. \ 1:llIlIa l Orth. Xl'\\' 1 ':Il~. ( I'rn ... Ilo,ton. :-;OC. \'al. I li,t. \ ',,1. .i~, p. 2tl3. 1920.) COlllst ock. Tilt. F nt. p. -1 (,0. l q2~ . Inl ill'. T ext hook I'llt. p, 231-1. 192.;. I':ssig. In s. \ \'e:, t. l\. A n1e r. p. (,3. 192(,. :' Bla t c hl .. ·\·. O r t h. l\urth-crt,tcrn .'\ mer. p. 42. jCJ2(). L ucas. 'B rit. Orlit . p. I. 1<l20. "l.uggn. (hth. \1 inn. 1'. 3. l X<J/. 10 B . C. E 1\ TOMOLOGICAL SOCIETY Apparently the geologic hi story o f these insects does not certainly extend back beyond Tertiary times. An insect, Baseopsis forficulina HeeT, has been obtained from the Lias in Switzerland,' but ento molo­ gists generally do not consider it to be an earwig. Above the Chalk, however, ill Tertiary formations of 0ligocel1 e and 'Miocene times, ear­ wigs certainly occur, and Scudder has not long since described a dozen species of o ne genus from the LO\\"er M iocene heds of Florissant a lone. Sometimes the \\'ings \\'ere expanded, and \\'e gather that the insect s have changed little in appearance, size, \\'ing-form, and wing expanse. The callipers, however, seem to have been dec idedly less conspicuous than at present (Lucas.)8 The comlllon na m e earwig was g iven to these insects in E ng land. and has reference to a widely spread fancy that these insects creep into the ears of sleeping per sons. Other similar names are applied t o them in Europe, Ohr-\Vurm in Germany, and Pe'rceoreille in France. On the other hand. it has been suggested that the \\'ork is a corruption o f " ear­ \\' ing" in a llusion to the form of the hind \\·ings. Ear \\'igs are small or of moderat e size; the li ving specIes m easur­ ing from 2.5 t o 3.7 111m. in length. The body is nan-ow and flat. T he head is short, 111 0r e or less heart-shaped, and hori zontal ; m a ndibles strong, fitted for chewing, and resemble in their more g eneral feat ures those of the Orthoptera. The antennae a re slender, and consist of from ten to thirty-fi ve segm ents : the second segm ent is a!\\'ays very sm all. The compound eyes a re rather large : but the ucelli are \\·anting. Fore­ \\'ings m odifi ed into vcry short leathery tegmina devoid of veins; hind \\' ings semicircul ar, m embranous, " 'itll tile vein s highly m odifi ed and di sposed radially. \ iV hen the vying is not in use. that part over \\'hich t he radiating veins extend is folded in pla its like a fan. after w hich the wing is folded twice crosswise. Many species a r e wingless. The legs are of nearly ertua l size . t he hind femora not enlarged: tarsi never more than tll1-c e-jointed a nd usua lly \\ithollt pads het\\'een the claws. The abdomen is elongate. the arrangement of the segm ents being imbricat e. a nd the abdoll1en being terminated by ce rci, which take the form o f callipers or forceps. Certain ear\\'igs possess stink-glands, which open through tubercl es situated one on each side near t he hi nd marg ins o f the second and third visible abdominal segm ents; from \\-hich. it is said, they can squirt a foul-smelling fluid to a di stance of three or four inches. The iurceps, or pincers are hom ologus \\·ith the cerci of other insects, a nd a re characteristic of the order. They are usuall y m or e highly developed in the male than in the female and young (in which ' ''Die Urwelt der Schweiz," by Prof. Oswald H ee r. 1865 BLucas. Brit. Orth. D. 7. 1920. PROCEEDINGS, 1929 11 they are much alike) in some exotic species being of extraordinary size and exceedingly odd form. They are sometimes as symmetrical, or even dimorphic in the same sex. (Plate 1, fig. 2, e.) Fulton says : "The u se of this most characteristic part of the earwig's anatomy is often referred to in works on entomology a s "obscure" and authors prefer to pass over the subject with a few very general remarks. From a r eview of the literature on earwigs and from studies of living material of two ' pecies, there is no longer any doubt in my mind but tha t the forceps a re ve ry useful organs a nd that their function varies t o some ext ent with the species. The m ost important use seems to be that of defence."9 Several species of earwigs have been said to u se the forceps as a means of offence against other insects. BennetPO says that he has seen the Maritime earwig. Anisolabis maritima, (Gene) in cages chase and catch \\·ith their forceps crickets, sand-fleas and smaller earwigs and devour them while still holding them w ith the forceps. SO pp" describes a case in which a female Labidura riparia (Pallas) captured w ith her forceps and devoured a blue bottle fly which had alighted near her hiding place. Later he sa\\' a male thrust its forceps backward into a hollo w among some sea-\y eed and pull out a large fl y which \\'as squeezed to cl eath by the forceps as he dragged it a\\'ay. T he fl y was held in the forceps until nearl y half eaten. Fulton has clearly shown that the fo rceps are used ior opening and closing the wings in the case of Forficula auricularia L i nnaeu s and Labia minor (Li nnaeu s), the latter species bei ng u nabl e to take fli g ht if the forceps are cut off. He has also clearl y shown that t he fo rceps of the male are not u see! as claspers during the act of copu­ 1 la tion ; this has been further substantiated by Morgan. " The forceps of the females of almost all ear\vigs are shorter tha n in the males, being. as a rule. straight and unarmed. 1\ few technical terms, other than those CO l1llll0 n to their close relatives. the O rthoptet"a , need explanation and a r e well described by Mor se.13 The la rge plate at the end of the abdomen a bove is called the anal plate or last dorsal plate; a similar one on the under side is the penultimate ventral segment, the ul t imate sho\\'in g only as t wo triangu­ lar plates bet\\-een the bases of the prongs of the forceps. exte nding downward and sometimes forward ; ra rely, it is fu sed with the a nal plate (Labidura riparia Pallis.) :\ttache cl t o its 100yc r (posterior) end is anothe r, the meta.pygidium, which is followed by the ielson or supra­ anal plate.