INSECT PARASITES AND PREDATORS OF INSECT PESTS \) 



The resting stage, which immediately precedes the appearance of 

 the adult insect, is passed within a white, spherical, parchment- 

 like cocoon formed in a curled leaf or in some other protected 

 place. 



The brown lacewing flies (species of Hemerobius and related 

 genera) are similar in habit to the green lacewings mentioned above, 

 but the body and wings of the adult are brown and the eyes lack 

 the conspicuous golden color. The larvae do not carry the protective 

 packet of trash, and they feed largely on aphids and mealybugs. 

 The eggs are laid singly among the host insects and are not borne 

 upon stalks. Many species pass the winter in the mature larval form 

 in sheltered places rather than within the cocoon, as do the larvae of 

 the green lacewings. The cocoon of the brown species is delicate, 



Figure 5. — The adult of Sphaerophoria cylindrica Say, one of the hover flies. X 7. 



oval in form, and consists of a loose network of silken strands 

 through which the pupa can readily be seen. 



HOVER FLIES 



The hover flies, of the family Syrphidae (fig. 5), are known to 

 most growers as rather large, conspicuously marked flies with rela- 

 tively long body and wings, which have a characteristic habit of 

 hovering over the blossoms upon which they feed or over foliage 

 infested with aphids. The adult flies feed upon honeydew secreted 

 by aphids and scale insects and also upon the nectar of plants, 

 whereas the larvae feed directly upon aphids and to a lesser extent 

 upon other soft-bodied insects, such as mealybugs, immature leaf 

 hoppers, and red spiders. Most of the aphid-feeding species may 

 be found in greatest numbers in the field during the spring and early 

 summer months. 



The eggs are usually about three times as long as wide, and those 

 of the larger species measure about one twenty-fifth of an inch in 

 length. They are chalky white and consequently conspicuous when 

 seen among the aphid colonies. 



108635°— 35 2 



