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THE WOOIiliY APHIS OF THE APPLE. 



Description and habits. — This insect exists in two forms, one of which 

 attacks the roots, the other the trunk and the branches of apple 

 trees. A great majority of the individuals are wingless, but winged 

 ones also occur, especially in the later broods of the year. The species 

 derives its name from a peculiar white fluffy substance which exudes 

 from the insects' bodies, making them appear as though covered with 

 cotton, and rendering them very conspicuous on the trees. The}^ are 

 especialh' liable to be abundant on the suckers from the bases of trees 

 and in the forks of the branches. The cottony covering serves to some 

 extent as a protection, so that this species is rather more difficult to 

 kill than other aphides. 



The root form of insect is the more injurious. By its attacks pecul- 

 iar galls are formed on the roots, in the crevices of which the lice may 

 he found. These galls not onlj^ interfere seriousl}' with the functions 

 of the roots, but also form centers of deca}^, and ma}^ cause the death 

 of the tree. 



The branch form weakens the tree b}" feeding on the sap, and not 

 infrequently causes the bark to split in places as the result of its 

 attacks; it never forms true galls like the root form. The entire life 

 of the woolly aphis is spent on the apple tree, the winter eggs being 

 laid in sheltered crevices. 



It must be understood that the two forms differ mainl}" in their 

 mode of life. The presence of either form will sooner or later give 

 rise to the other, and badl}' infested trees are sure to be attacked both 

 on the roots and on the branches. 



This insect is most abundant in the Coast region. In Washington 

 the writer has frequently searched for the root form without success. 

 Professor Cordley reports it from the Willamette Valley. 



Remedies. — This pest is far more likeh" to be introduced on nursery 

 stock than in any other wa}'. The roots of purchased apple trees should 

 always be examined for the galls of this insect; if the galls are large 

 or numerous, reject the trees. If they are small and few, they may be 

 completely disinfected bj^ dipping the roots in kerosene emulsion or 

 in hot water (12()°-140° F.) for a moment. If trees in the orchard 

 are attacked by the root form, the soil should be removed as much as 

 possible from them and the roots thoroughl}' treated with kerosene 

 emulsion or with water heated nearly to the boiling point. 



For the branch form, spray with kerosene enmlsion, using rather 

 stronger solutions than for other aphides. 



The root galls caused by this insect should not be confounded with 

 those of the crown-gall disease described elsewhere. Trees infested 

 with the latter disease can not be disinfected by an}' known means. 

 The safest rule is not to accept any trees with galls on the roots. 



