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CIRCULAR 2 7 0, U. S. DEPARTMENT OF AGRICULTURE 



and scale insects. Most of these species lay yellow or orange-colored 

 cigar-shaped eggs, which stand on end in clusters. The young, or 

 larvae, are usually black or gray, with various red or orange markings. 

 Some of them are covered with a white waxy secretion, giving them the 

 appearance of mealybugs. Although most of the ladybeetles are con- 

 spicuous, they are not molested by 

 birds, possibly because they have a 

 disagreeable taste. 



The larvae of syrphus flies are 

 very common enemies of aphids and 

 are most often found in colonies of 

 the woolly aphid. Frequently they 

 destroy the colonies entirely. 

 These larvae or maggots (fig. 77) 

 are nearly one-half of an inch long 

 when full-grown, yellowish or gray- 

 ish, and often with a stripe down 

 the (back. The body is widest 

 behind, and the narrow head is 

 restlessly moved about as the mag- 

 got searches, for food. No legs are 

 evident. The adult syrphus flies 

 (fig. 78) are usually black, striped 

 with yellow, and may be mistaken 

 for wasps or bees. They fly actively 

 and often poise in midair before 

 darting down to a colony of aphids 

 to deposit their eggs. The eggs are 

 elongated, dirty whitish, and are 

 laid singly among the aphids. 



The young of lacewing flies (fig. 

 79) are effective enemies of aphids, 

 and also feed on other insects, such 

 as red spiders, newly hatched cod- 

 ling moth larvae, and the young of 

 leafhoppers. These larvae, which 

 are known as aphis lions, are flat, 

 elongated, tapering at both ends, 

 with long legs and conspicuous 

 sickle-shaped jaws. When mature 

 they are about three-eighths of an 

 inch long, grayish or yellowish, with 

 red or brown markings. They spin spherical white cocoons, which 

 are sometimes found in codling-moth bands, and from which the 

 adults escape by cutting circular lids. The adults are light green with 

 delicate transparent wings and golden eyes. They emit a very dis- 

 agreeable odor when crushed, and this doubtless protects them from 

 birds and other enemies in the same manner as ladybeetles are pro- 

 tected. The eggs are deposited in clusters, each egg on a long stalk 

 (fig. 80) ; this is believed to prevent the eggs from being eaten by the 

 young or by other insects. 



In addition to the many predacious bugs and beetles that prey on 

 various insects, there are hosts of small, inconspicuous parasitic 

 insects, mostly related to the bees and wasps, that take their toll of the 



Figure 78. — Syrphus fly killed by 

 fungous disease. X 2. 



