572 Report of the Entomologists of the 



Appearance of Infested Trees. 



It is usually a very easy matter to detect the presence of the 

 woolly aphis, especially on young trees. They may live on the 

 ^^^ots of old trees without cansinj^- any ap[>ar('nt injury or change 

 in the general appearance of the trees. They also frequently 

 escape detection on the rough bark of an old tre<'. On young 

 trees, and especially trees yet in the nursery, the presence of this 

 insect is more apparent. Usually the white cottony tufts hanging 

 from the infested limbs readily attract the eye, but frequently 

 the tree may be infested above ground when the limbs are free 

 from the tufts of cotton. In such cases a few of the lice 

 will be found in the wounds made by trimming the tree too 

 close. This applies to nursery stock especially. We have fre- 

 quently found infested trees in the packing yard which at first 

 appeared to be free from the lice, but upon close examination 

 a number of the hibernating insects could be found almost con- 

 cealed in the wounds made by too close trimming of the tree. 

 We have also found the roots of young apple trees badly infested 

 when there were no traces of the lice on the other parts of the 

 tree, and in many cases the trunk and limbs were infested, 

 although the roots were entirely free. When the roots are badly 

 infested, however, the whole tree is likely to present a sickly 

 appearance. 



Appearance of infested roots. — When first dug, young nursery 

 trees whose roots are infested with the aphis will usually carry 

 with them a good deal more of the soil than is usual with healthy 

 roots. This is due to the fact that the roots, including many 

 of the fibrous roots, are enlarged and deformed with galls. 

 There also seems to be an unusual abundance of fibrous roots. 

 These are often matted together and with the deformed and swol- 

 len roots form a support for the dirt. Plate XLIV, fig. 2, is from 

 a photograph of the infested roots of a young apple tree as they 

 appeared before the dirt was i-emoved. It is evident that the 

 amount of soil clinging to the roots would depend largely upon the 

 nature of the soil and the extent to which the roots were infested, 

 but even where the trees were grown in a very light sandy loam 



