REVISION OF STREPSIPTERA — PIERCE. 83 



Strepsiptera, 1883 (a family, Coleoptera, Ileteromera), Sharp, 1881; Karsch, 1883; 

 Sharp, 1895-1898; Seidlitz, 1903-1905. 



Strepsiptera, 1885 (a family, Coleoptera, Malacodermata), Prauer, 1885. 



Stylopinx, 1900 (a subfamily, Coleoptera, Melandryidse), Lameere, 1900. 



Xenidx, 1902 (a family, Coleoptera, Tenebrionoidea, near Rhipidophoridse), Se- 

 menov, 1902; Jacobson, 1904. 



characterization. 



An order of hypermetamorphic endoparasitic insects with highly 

 specialized reduction of certain functional organs, great specialization 

 of other functional organs, and with dissimilar sexes. 



Hale. — Elytrophorous, winged, ephemeral, aerial. Head and tho- 

 racic segments united by elastic commissures. Head transverse, 

 with eyes stalked and composed of regularly placed separated hexag- 

 onal ommatidia. Mouthparts specialized, rudimentary, vestigial, or 

 lacking. Labrum and labium absent; pharynx presenting a great 

 exposed surface which is folded crater-like and contracts into a small 

 tube distant from the appendages; mandibles and maxillae arising 

 beneath the genae near their base; maxillae more or less reduced. 

 Antennae sensitive, with one or more joints laterally produced. 



Thorax with principal parts capable of independent movement. 

 Prothorax much reduced; mesothorax reduced; metathorax greatly 

 elongated, occupying at least one-half the length of the body and 

 apically covering the base of the abdomen. Front coxal cavities 

 open behind; tarsi with each joint pulvilliform below (except in 

 Mengeidae and Myrmecolacidae) ; tarsal claws present in only the 

 Mengeidae. The legs are unfit for use except in adhering to the body 

 of the female's host during copulation, which is the only function of 

 the males. Halteres, or balancers, attached very low on the meso- 

 pleurae and not serving as a protection to the wings, deformed and 

 greatly reduced. The mesostigmata are frequently protected by a 

 lobe-like process beneath the base of each elytron. Wings folded 

 longitudinally; veining simple, radial. Genitalia with cedeagus ex- 

 posed, arising at tip of ninth segment; ninth segment ventrally 

 much surpassing tenth, at the tip of which is the anus. 



Female. — Larviform, apodous, permanently endoparasitic, inclosed 

 by the persistent skin of the pupa. Pupa larviform, apodous. 



Head and thorax adnate, forming an acariform chitinized disk, 

 separated by a constriction from the sac-like abdomen. This disk, 

 the cephalothorax, protrudes from between the abdominal segments 

 of the host, with the oral or ventral surface upwards. Mouth parts 

 vestigial. Eyes lacking. Thorax separated ventrally from head by 

 opening of brood canal, an intermembranal conduit between pupal 

 and adult skins leading from the genital apertures on the second to 

 fifth segments anteriad to this ventral slit. 



