ATTACKING THE BRANCHES. 29 



growers to take particular pains to destroy these lice wher- 

 ever found, for the colony that is permitted this year to 

 establish itself upon some wortliless tree or on the shoots 

 or suckers at its base, will furnish the parents of countless 

 hosts that may establish themselves next year on the choicest 

 trees in the orchard. The insects are extremely hardy, and 

 will endure a considerable amount of frost, and it is quite 

 probable that some of them survive the winter in the perfect 

 state in the cracks of the bark of the trees. 



The eggs are so small that they require a raagnifying-glass 

 to enable one to see them, and are deposited in the crevices 

 of the bark at or near the surface of the ground, especially 

 about the base of suckers, where such are permitted to grow. 

 The young, when first hatched, are covered with very fine 

 down, and appear in the spring of the year like little specks 

 of mould on the trees. As the season advances, and the in- 

 sect increases in size, its cottony coating becomes more dis- 

 tinct, the fibres increasing in length and apparently issuing 

 from all the pores of the skin of the abdomen. This coating 

 is very easily removed, adhering to the fingers when touched. 

 Both young and old derive their nourishment from the sap 

 of the tree, and the constant punctures they make give rise to 

 warts and excrescences on the bark, and openings in it, and, 

 where very numerous, the limbs attacked become sickly, the 

 leaves turn yellow and drop off, and sometimes the tree dies. 



Remedies. — The very small four- 

 winged Chalcid fly, Aphelinus mail 

 (Hald.), which is highly magnified in 

 Fig. 15, and which has already been 

 referred to under No. 1, preys also 

 on this woolly aphis. The lady- 

 birds and their larvae, also the larvse 

 of the lace-wing flies and syrphus 

 flies, feed on all species of plant-lice, 



and are very useful in keeping them within bounds. These 

 friendly insects will be fully treated of under the Apple- 



