574 Report of the Entomologists of the 



of old trees, or in other protected places on the trunk or limbs. 

 We have occasionally found them during the winter on the under 

 sides of the limbs of nursery trees. Usually, however, they 

 should be looked for in the scars made by trimming the tree too 

 close, as shown in Plate XLV, fig. 3. Sometimes only two or 

 three of the lice will be found, but they may be easily recog- 

 nized by their white, woolly covering. During the past few 

 months we have examined a large number of these winter colo- 

 nies, and in every case have found the lice present in various 

 sizes, from, the very small larvae to the nearly full grown insect. 

 The winter eggs are also placed in sheltered places such as these. 



Importance as a Pest to Nursery Stock. 



Although the woolly aphis does serious injury to the young 

 trees in the orchard and sometimes to older ones as well, yet it 

 is the nurseryman who suffers most from the depredations of 

 the lice. When once well started in a nursery, this insect may 

 make thousands of apple trees unsalable. When examining nur- 

 sery stock last season, we found many thousands of trees which 

 had become infested. In a majority of cases, apple trees only 

 were found infested, but where pear, or quince trees were grown 

 next to blocks of infested apple trees, they, too, became infested 

 with the lice. We have never found them occurring in such large 

 numbers on either penr or quince trees, however, as on apple. 

 Of the apple trees which we examined, the " Ben Davis " and 

 " Yellow Transparent •' varieties were found infested more fre- 

 quently than any other, and when occurring on pears, the " Bart- 

 lett " variety. 



This insect is also of especial importance as a pest to nursery 

 stock, because if is by iu(>aiis of infested stock that it is distrib- 

 uted throughout the country. When only a very few of the in- 

 sects occur on a tree, tliey are very easily overlooked, or, per- 

 haps, are not recognized when found, as most growers and deal- 

 ers seem to be familiar with the insect only as it appears when 

 occurring in large numbers on the branches of the trees or when 

 infesting tho roots. 



