METAZOA INSECTA. 423 



basal portion is chitinous and has few veins, while the 

 terminal part is membranous and is richly supplied with 

 veins. The under wings (fig. 3, w") are membranous 

 throughout but have few veins. Both pairs of wings lie 

 flat upon the back and their tips overlap. 



Peculiar specializations are found in many of the adult 

 Heteroptera, the reasons for which are not always known, 

 owing chiefly to the fact that much information in regard 

 to the habits of the insects is wanting. 



The thread-legged bugs like Emesa (No. 1049) have 

 the habit of hanging to twigs by their long legs and 

 swinging backward and forward. The fore legs are pro- 

 vided with claws for seizing their prey and are well fitted 

 for this purpose. 



Especially attractive is the lace-bug, Corythuca arcuata 

 Say (No. 1050). This insect lives on the under side of 

 oak leaves where its eggs (PI. 1051, fig. i) are laid. The 

 larva (fig. 2) has such a spiny thorax and abdomen that 

 it looks like "a lobe of a prickly cactus" (Comstock). 

 The adult (fig. 3) is distinguished from other insects by 

 the exquisite gauzy appearance of the body. This is due 

 to the wing covers that are formed of a nearly transpar- 

 ent membrane netted with veins. 



Prionidus cristatus Linn., or the wheel-bug (No. 1052) 

 destroys great numbers of caterpillars and other insects. 

 Both as larva and adult it is a hardy, rapacious creature, 

 and it may be that the cog-wheel crest of the thorax (No. 

 1052) gives strength to the animal when making its 

 attacks. 



In Scutellera (No. 1053) the scutellum of the meso- 

 thorax has developed for some reason so that it covers 

 both pairs of wings and resembles, at first sight, the horny 

 wing cases of the beetles. 



Among the more specialized Heteroptera is the bed-bug, 

 Acanthia hctularia (No. 1054 ) . It is adapted to its hab- 

 itat by having a flattened body, strong mouth parts, and 

 a thorax that is almost entirely unencumbered by wings. 



