Orchard insects of the pacific northwest 



65 



codling-moth larvae, and the young of leaf hoppers. 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 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 

 disagreeable odor when crushed, 

 and tins doubtless protects them 

 from birds and other enemies in 

 the same manner as lady beetles 

 are protected. The eggs are de- 

 posited 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 preda- 

 cious 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 pests. Among these may be 

 mentioned Ascogaster carpocapsae 

 Vier., which has been introduced 

 into the Northwest, and winch at 

 times parasitizes 25 or 30 percent 

 of the codling moth larvae ; Tricho- 

 gramma minutum Riley, one of the 

 smallest insects, which parasitizes 

 the eggs of the codling moth and 

 other pests; and Aphelinus mali 

 Hald. , a parasite of the woolly apple 

 aphid (fig. 81), which is being intro- 

 duced into the Pacific Northwest. 



It is difficult to estimate the 

 amount of benefit done by preda- 

 cious and parasitic insects. The 

 beneficial species prevent many po- 

 tentially harmful insects from becoming numerous, and therefore 

 should be encouraged in every way. Frequently, also, outbreaks of 

 serious pests are stopped more completely by beneficial insects than 

 they can be stopped with artificial control measures. Unfortunately 

 the beneficial forms often do not begin to be effective until after the 

 harmful species have done much damage, and the fruit grower cannot 

 afford to wait but must control the pests himself. The sprays applied 

 to trees, particularly the contact sprays, may destroy many of the 

 beneficial insects. However, since the adults usually are not harmed, 

 being able to avoid the spray, they are able to return, and they or 

 their young may rapidly complete the destruction of the pests which 

 has not been entirely accomplished with the insecticides. 



Figure 78. 



Syrphus fly killed by tungous disease. 

 Twice natural size. 



