THE PHYLA ARTHROPODA AND ONYCHOPHORA 



Fig. 15.29. Hemiplera. A 

 cone-nose bue;, Trinlnma. 

 Note the extended mouth 

 parts, modified for piercins; 

 and bloodsucking, and the 

 characteristicalK' half-mem- 

 branous wine;s. (Photograph 

 by E. S. Ross.) 



adapted for piercing and sucking, and their wings showing the X-shaped 

 pattern by which hemipterans are commonly recognized. The aduhs hiber- 

 nate over the winter, dying in the spring soon after eggs have been laid upon 

 the sprouts of vines where the young will feed. The nymphs, like those of the 

 locust, are at first wingless individuals which undergo a series of molts before 

 attaining adulthood. They feed by piercing the leaves and stems of the plant 

 with their beak-like mouth parts and sucking the juices. 



Most hemipterans appear to feed upon plant juices, but the members of 

 some families are predators upon other insects. A few, like the assassin bugs, 

 habitually attack vertebrates, piercing the skin and sucking blood (Fig. 15.29). 

 This is the chief means of infection and spread of the affliction of man known 

 as Chagas' disease, native to the American tropics. The causative organism 

 is a blood-inhabiting flagellate protozoan, Trypanosoma cruzi, which multiplies 

 in the gut of the insect host, very much like the parasite causing African sleep- 

 ing sickness (p. 244). 



Order Coleoptera (sheath wings) — widely distributed and highly varied 

 insects known as beetles. The mouth parts are mandibulate but in the wee- 

 vils, or snout beetles, form a piercing beak. The anterior pair of wings are 

 modified as stout covers beneath which the posterior wings are folded in a 

 complex manner. The life cycle of beetles is holometabolous. 



463 



