HANDBOOK OX INSECT ENEMIES OF FLOWERS AND SHRUBS 69 



Treatment. — If the infestation is 

 heavy, spray or dust with lead arsenate, 

 preferably while the larvae are still 

 small. Derris powder as a dust or 

 spray is also effective. When only a 

 few groups of larvae occur on small 

 trees they may be picked off, or the in- 

 fested twigs may be removed and the 

 insects destroyed. 



Pine Bark Aphid 



An infestation of the pine bark aphid 

 {Pineus strobi (Htg.)) can be recognized 

 by spots or patches of white cottony 

 material on the smoother bark of the 

 trunks and branches (fig. 114). White 



Figure 114. — White pine stem infested 

 with the pine bark aphid. About 

 natural size. 



pine is most commonly attacked, al- 

 though- Scotch and Austrian and possi- 

 bly other pines are occasionally infested 

 throughout the East. Continued heavy 

 infestations probably weaken the trees, 

 and trees in poor vigor may suffer con- 

 siderably from these small insects suck- 

 ing the sap. The aphids presumably 

 pass the winter under the cottony 

 masses. At least three generations de- 

 velop during the season, the young 

 usually hatching in the latter part of 



May, the first half of July, and in Au- 

 gust. The aphids are very small, oval, 

 and their bodies are covered with a 

 white waxy secretion, which is the 

 white material observed on the bark. 



Treatment. — Spray with a miscible 

 oil or oil emulsion in the spring before 

 the buds open. When the young are 

 hatching, a nicotine sulfate and soap 

 solution or a combination of white-oil 

 emulsion and nicotine (p. 101) may be 

 used. These sprays should be applied 

 with considerable force so as to wet the 

 bodies of the insects protected by the 

 cottony material. Many of the insects 

 can be washed off with a strong stream 

 of water. Washing the trees a day or 

 two before spraying might improve the 

 results. On small trees, scrubbing with 

 a brush and soapy water would no doubt 

 give good control. 



White-Pine Aphid 



The white-pine aphid (Cinara strobi 

 (Fitch)) is a comparatively large blackish 

 plant louse that is found' in colonies on 

 the smooth bark of twigs and small 

 branches of white pine. Heavily in- 

 fested branches may show thin or pale 

 foliage, and the bark is usually black- 

 ened by a sooty mold that develops in 

 the honeydew excreted by these sucking 

 insects. Young trees may be injured 

 considerably, and in some years the 

 weakened trees may be further damaged 

 by winter injury. The aphid is usually 

 most abundant in spring and fall. It 

 passes the winter in the egg stage, the 

 elongate blackish eggs being placed in 

 rows on the pine needles. 



Somewhat similar species of aphids 

 occasionally infest other kinds of pine 

 trees, feeding on the bark of twigs or on 

 the needles. These aphids are often 

 held in check by natural enemies and 

 cause little injury; however, continued 

 heavy attacks may weaken the badly 

 infested branches. 



Treatment. — Same as given for 

 aphids (p. 9). On white pine, watch 

 for spring and fall infestations and ap- 

 ply control measures promptly. 



Pine Needle Scale 



The needles of various species and 

 varieties of pine, especially of Austrian, 

 mugho, and red pines, are often whit- 

 ened by infestations of the pine needle 

 scale (Phenacaspis pinifoliae (FitclOV 

 The sucking of the plant juices by this 

 scale causes the foliage of infested t rec- 

 to become weakened, pale, and sickly 

 in appearance. The female scale is 

 white, waxy, pear-shaped, and about 



