PHYLUM ARTHROPOD A 



273 



Order Thysanoptera 



Small insects known as thrips, common on flowers. Thrips 

 They feed on the 

 sap of plants, 

 and are often 

 injurious. The 

 metamorphosis 

 is quite incom- 



WingS 



5 x a i; a ,, a l Museum 



From Bu u etin 

 are Usually pres- FIG. 89. Tobacco thrips: a, adult; b, antenna of same; 



ent in the adults, c ' young larva ; d ' full - grown larva ' 



but many species are wingless. 



Order Trichoptera 



The caddis flies, formerly placed with the Neuroptera, Caddis flies 

 but really more nearly allied to the Lepidoptera. The 

 larvae are aquatic, and usually construct cylindrical 

 cases. In one genus the larva case resembles a snail, 

 and was once described as such by an eminent natural- 

 ist. Some of the adults are so similar to moths as to 

 lead to confusion, but the hind wings are folded length- 

 wise when at rest, which is not true of the Lepidoptera. 



From Bulletin 67, V. S. National Museum (after Packard) 

 FIG. 90. A caddis fly, larva, and its case. 



