The Green Lacewings of the Genus Chrysopa in Maryland ( Neuroptera: Chrysopidae)

The Green Lacewings of the Genus Chrysopa in Maryland ( Neuroptera: Chrysopidae) Ralph A. Bram and William E. Bickley Department of Entomology INTRODUCTION Tlw green lacewings which are members of the genus Chrysopa are extreme- ly lwndicia1 insects. The larvae are commonly called aphislions and are well known as predators of aphids and other injurious insects. They play an important part in the regulation of populations of pests under natural conditions, and in California they have been cultured in mass and released for the control of mealy- bugs ( Finney, 1948 and 1950) . The positive identification of members of the genus is desirable for the use of biological-control workers and entomologists in general. Descriptions of most of the Nearctic species of Chrysopidae have relied heavily on body pigmentation and to a lesser extent on wing shape, venational patterns and coloration. Specimens fade when preserved in alcohol or on pins, and natural variation in color patterns occurs in many species ( Smith 1922, Bickley 1952). It is partly for these reasons that some of the most common and relatively abundant representatives of the family are not easily recognized. The chrysopid fauna of North America was treated comprehensively by Banks ( 1903). Smith ( 1922) contributed valuable information about the biology of the green lacewings and about the morphology and taxonomy of the larvae. He also pro- vided k<'ys and other help for the identification of species from Kansas ( 1925, 1934) and Canada ( 1932). Froeschner ( 194 7) similarly dealt with Missouri species. Bickley and MacLeod ( 1956) presented a review of the family as known to occur in the N earctic region north of Mexico. This paper included keys to the eight genera and to certain species groups as then understood. Subsequently Adams ( 1956) described the genus Pimachrysa. The task of analysing taxonomic characters and evaluating generic and specific relationships is so complex that progress is very slow. Some of the diffi- culties were discussed by Bickley and MacLeod ( 1956). The work here reported represents an attempt to clarify the status of a limited number of species. We recognize the desirability of a more thorough treatment, but we believe that many years will elapse before completion of a revision. In the meantime a key and othPr means for identifying Maryland species of Chrysopa should be helpful to any- one dealing with the fauna of Maryland and other eastern states. The species ?f Chrysopa included are undoubtedly the dominant representatives of the genus in North America east of the Rocky Mountains and north of Florida and south- ern Texas. More extensive collect'ing will make possible studies which will change distribution patterns and narrow the field of usefulness of the key. (_ .. The clarification of the status of the 10 species has been accomplished by Utilizing structures of the rnale genitalia as taxonomic characters. The term, external genitalia, is commonly reserved for the sclerotized structures of the seg- rne~t which contains the genital aperture. Terminalia is the generalized term which refers to all sclerotized structures of the 8th, 9th, 10th, and 11th abdominal segments. PREPARATION OF TERMINALIA FOR STUDY To prepare male t~rmin~.Iia f?r study, the la~t four or five ab~ominal segments were removed with nncrosc1ssors. The portion removed was nnmersed in 15-percent KOH solution and heated in a water bath for 15 minutes. It was then gently flushed with a 1 ml. hypodermic syringe equipped with a 27-gauge needle, which was inserted through the open end of the abdomen. The specimen was then rinsed in distilled water. StaininK~ suggested by Dr. P. Adams ( per~onal communication), was accomplished by 'immersing the entire abdomen for 2 to :3 minutes in a drop of 5-percent Chlorazol Black E aqueous solution. The specimen was again rinsed in distilled water and pJaced in one drop of glycerine on a slide. Specimens were permanently stored in microvials containing glycerin<\ MORPHOLOGY AND TERMINOLOGY OF THE MALE TERMINALIA Banks ( 1903) pointed out a few differences in the gross structure of the external genitalia. Smith ( 1932) recommended the study of the male genitalia and suggested staining with Biebricht'~ scarlet. Tjeder ( 1936) described the male genitalia of several Chinese chrysopids. Killington ( 1936 and 1937) figur~d the male genitalia of many British species, and Principi ( 1949) made detailed studies of the genitalia of several Palearctic chrysopids. The male genitalia of four Australian chrysopids were described by Kimmins ( 1952). Tjeder ( 1954 and 1956) attempted to stabilize the terminology of gen'ital structures in the order Neuroptera. Howe~er, not all subsequent workers have accepted thP "neutral terms" which he proposed. Although Hwang and Bickley ( 1961 ) followed the terminology of Tjeder in describing the structures of Chryso/Ja oculata Say, Zimmerman (1957) followed, to a degree, the terminology of Kill-- ington in describing Hawaiian chrysopids. Adams ( 1959) applied some na nws differently when describing Micronesian forms. A morphological interpretation of the male terminalia of all neuropteran families was undertaken by Acker ( 1960) . He found that more than 125 terms have been applied, and in the case of the chrysopids his usage of terms varies to some extent from that of other authors. Perhaps the basis for disagreement jn the interpretation of genitalic organs lies in the origin of the genitalia. Gustafson ( 1950) presented a historical survey of this problem and pointed out that the male genitalia in insects are usually regarded as belonging entirely to the ninth segment. In contrast_, \Vheeler ( 189~1), Else ( 1934), and Roonwal ( 1937) suggested that the genitalia arise from the lateral and sternal regions of the tenth segment. But Snodgrass ( 1935) reported that the male phallic organs ari~e from the conjunctiva] membrane behind the ninth sternum. Acker ( 1960) concluded that the genitalia of neuroptnans arise from the tenth sternite and coxopodite. Since there is such a diversity in taxonomic terms available for the description of male tenninalia, there seems to be no purpose in adding new terminology to an already confused situation. In referring to the male termina.lia, the n.omenclatorial system followed by Tjcder ( 1954 and 1956) and modified by Hwang and Bickley ( 196 I ) is used. The structures of the terminalia which are employed as taxonomic characters a re: the gonocristae, the transverse arch, the gonarcus, the entoprocessus, the pseudopenis, and the processus. The gonocristae ( fig. 26-31) 1 are a pair of retort-shaped, sclerotized pb te~ 1The illustrations are grouped into five Plates, pages 14:-18. Text, refert>tH'f's art> to 1tlafr sc•d 1011.., bearing arabic numerals, which run consecutivel;v through the fh'e illustrations. 2 which are located on the dorsal surface of the hypovalva (fig. 12). These plates carry scale-like, overlapping teeth and in some species are connected by a transverse band of teeth. The gonocristae have been found in the genus Chrysopa only in species having oculata-like and lineaticornis-like terminalia. The transverse arch ( fig. 5) is composed of a pair of arched, anteriorly projecting arms which fuse posteriorly, producing a small backward-projecting tu- bercle. The arch terminates anteriorly with small hooks projecting later- ally, which are attached just inside the callus cerci ( fig. 3) . The posterior tuber- cle may be seen to project from the abdomen just below the anus. The transverse arch has been found only in those species of Chrysopa having carnea-like term inalia. The gonarcus ( fig. 5) is situated internally between the anal segment and the ninth sternite. It is an arched structure with the paired, concave wings projecting anteriorly and fused posteriorly. In species having carnea-like terminalia, the wings of the gonarcus fuse posteriorly in a "V" -shaped juncture ( fig. 6) . In oculat a-like terminalia the wings of the gonarcus are parallel and are fused posteriorly by a thin, chitinous transverse bridge ( fig. 14) . Small, posteriorly directed processes may arise from the ventral surface of the transverse bridge. The point of fusion may also serve as a point of attachment for the pseudopenis in carnea-like tcnninalia ( fig. 6) . Directly beneath, and attached to the gonarcus is the entoprocessus ( fig. 5). In species with oculata-like terminalia, the entoprocessus is composed of paired, posteriorly directed processes which are fused to the ventral edge of the wings of the gonarcus (fig. 12). In species having carnea-like terminalia, the entoprocessus is represented by small triangular sclerites which are fused directly to the ventral edge of the wings of the gonarcus ( fig. 5) . The pseudopenis is a curved, tubelike, unpaired organ which Tjeder ( 1954 and 1956) considers to be derived from the fused parameres. In species with carnea-Iike terminalia, the pseudopenis is joined to the gonarcus at the point of fusion of the wings ( fig. 5) . It appears to articulate with the gonarcus. In oculata- like terminalia, the pseudopenis is not articulated with the gonarcus and appears as a large pointed structure (fig. 13) . In species possessing lineaticornis-like terminalia, a heavily sclerotized, unpaired process articulates at the hypovalva ( fig. 23) . This structure is internally directed anteriorly and terminates before reaching the eighth segment. A homo- logous process in the corydalids was called the columna by Crampton ( 1918 a and 1918 b). Tjeder ( 1954 and 1956) named a similar prolongation in a differ- ent corydalid species the processus. Tjeder's terminology is adopted here. The callus cerci are considered by most authors to be vestiges of the eleventh coxopodites or cerci. In the Neuroptera the cerci have been reduced to a pair of small pads located on the tenth tergite and containing sensory setae set in rosette sockets called trichobothria ( fig.

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