THE PHYLA ARTHROPODA AND ONYCHOPHORA 



way out of the cocoon to spread and dry its wings (Figs. 15.32, 15.33). I'he 

 household pest known as the clothes moth (Tineola bisselliella) is a familiar 

 example of this group; the silkworm, used in the Orient and in Europe for 

 the commercial production of silk, is the larva of a large moth, Bombyx mori. 

 Several species of giant silkworm moths are found in North America and, be- 

 cause of the large size of their larvae and pupae, have been very useful in 

 studies on the biochemistry and endocrine control of metamorphosis. 



Order Hymenoptera (membrane wings) — ants, bees, wasps, etc. The 

 mouth parts are typically mandibulate but in the adult are often modified to 

 form a tongue-like structure adapted for lapping liquids. The wings are 

 membranous, and two pairs are usually present. The life cycle is holo- 

 metabolous, with complete metamorphosis. 



The Hymenoptera include a variety of types, ranging from insects of rela- 

 tively simple habits to species with highly developed social organizations, 

 such as honeybees and some ants. The examples that follow will illustrate 

 this diversity. 



Fig. 15.34. Parasitism among insects. The large caterpillar (tomato hornworm) bears manv 

 cocoons of a small hvmenopteran. An adult wasp deposited her eggs on the caterpillar, and the 

 wasp larvae fed extensively on the tissues of the host before emerging to spin their cocoons and 

 pupate. Such a para.sitized caterpillar is incapable of completing its own life cycle; thus insects 

 parasitizing other insects play an important role in the control of many agricultural pests. 

 (Photograph by Charles Walcott.) 



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