COLLECTING ECONOMIC PLANT DATA 



49 



Figure 34. — Developmental stages in various kinds of insect pests. A, Seed-corn 

 maggot: a, Maggot; b, pupa; c, adult fly (all enlarged). B, Cabbageworm: a, Egg 

 (much enlarged); b, caterpillar; c, pupa; d, adult butterfly. C, Bark beetle: a, Larva; 

 b, adult beetle (both considerably enlarged). D, Grasshopper: a, Newly hatched nymph 

 (magnified); b, adult (about natural size). E, Leafhoppers: a, Two nymphs; b, adult 

 (all considerably enlarged). F, Scale insects: a, Nymph, just hatched (all greatly en- 

 larged). G, Aphids (plant lice): a, Young nymph; b, wingless, adult female; c, winged, 

 adult female (all greatly enlarged). H, Squash bug: a, Eggs (natural size); b, young 

 nymph (about twice natural size); c, adult (about twice natural size). 



chewing mouth parts, and commonly both stages are destructive to 

 plants. Both the nymphs and adults of grasshoppers have chewing- 

 mouth parts and likewise both cause damage. Leaf-cutting ants com- 

 monly destroy foliage in the Tropics, but in this case the plant material 

 is not actually devoured but is carried to the nest to be used for grow- 

 ing fungi, which in turn serve as food. 



Insects with the piercing-sucking type of mouth parts include the 

 leafhoppers, aphids, true bugs, scale insects, thrips, and white flies. 



