ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



63 



peach trees in the Pacific Northwest, and the reader is referred to page 

 51 for a discussion of this insect. 



STONE FLIES 



Stone flies or salmon flies (Taeniopteryx pacifica Banks) occasionally 

 injure the buds of peach, apricot, and plum trees in the spring (fig. 74), 

 particularly where these trees are growing near the Columbia River or 

 some other large stream. The young of these insects live in the 

 streams, and the adult flies emerge early in the spring, when thousands 

 of cast skins from which the flies have emerged may be found among 

 the rocks along the stream banks. The flies feed on the fruit buds 

 mostly during warm, sunny weather, destroying many of the buds and 

 injuring others so that they produce deformed fruit. If control is 

 necessary, lead arsenate, 

 at the rate of 2 pounds 

 to 100 gallons of water, 

 should be effective if 

 applied as soon as the 

 insects appear. 



WALNUT INSECTS 

 WALNUT APHID 



The walnut aphid 

 (Chromaphis juglan- 

 dicola Kalt.) is the only 

 insect pest of any impor- 

 tance on walnut trees 



in the Pacific North- I Figure 74.— Stone fly feeding on peach bud. Twice natural size. 



west. It is a small, 



pale-yellow, wingless or winged insect found on the underside of the 

 leaves, often in considerable numbers. These aphids secrete a sticky 

 liquid known as honeydew, which covers the leaves and nuts, and 

 in which a black fungus grows. Syrphus flies, lady beetles, and 

 other natural enemies of aphids (p. 64) usually keep this pest in check 

 so that artificial control is unnecessary. If these beneficial insects 

 fail, the aphid may successfully be combated with nicotine sulphate (40 

 percent nicotine), % pint to 100 gallons of water, to which is added soap 

 or spreader, or a 2 percent nicotine dust (2% pounds of nicotine sul- 

 phate to 47)o pounds of hydrated lime) may be used. 



BENEFICIAL INSECTS 



Not all of the insects found in an orchard are harmful. Many are 

 of no importance, either because they are not sufficiently numerous, 

 or because they are not injuring the trees or the cover crop. Many 

 others are entirely beneficial because they feed on some of the insects 

 that are harmful to the crops. Fruit growers should be able to recog- 

 nize these beneficial insects in order that they may not destroy them, 

 thinking them to be harmful. The most conspicuous beneficial insects 

 and the ones most often found in an orchard are those that prey on 

 various species of aphids. These insects are very important factors 

 in reducing the numbers of aphids, and their work is most likely to be 

 effective during warm weather when they are active and are multi- 

 plying rapidly.^ 



