clear- winged, gnat-like objects, greenish-brown, almost black in color, 

 with the body covered with more or less of the cottony excretion. 



The aerial colonies are probably killed out every winter in the colder 

 northern districts, but in the warmer latitudes the partly grown indi- 

 viduals, at least, survive protected in crevices or under bits of bark, 

 and remain more or less active during winter and renew the colonies 

 the following spring. This has been shown to be true in the District 

 of Columbia, and also in the interior regions of the same latitude, in 

 spite of the much colder winters. The root form survives the winter 

 usually in an immature condition, viz, larvae in various stages of 

 development, and both in latitudes where the aerial forms are killed 

 by the severity of the winter and elsewhere it seems probable that there 

 is a regular upward migration in spring and early summer from the 

 roots, the aerial colonies appearing first near the crown and at a later 

 period on the higher parts of the trees. At any time during the sum- 

 mer and fall there may be migrations to the roots, and throughout the 

 year the subterranean colonies are maintained. 



The spread of the insect is accomplished in part b}- the viviparous 

 females, which appear in late summer, but quite as commonly perhaps 

 b}^ the transporting of young or partly' grown individuals from tree to 

 tree or to distant orchards by means of birds or insects to which they 

 have attached themselves. Its wide distribution is usually dependent 

 on the traffic in nursery stock. 



REMEDIES AND PREVENTIVES. 



The foregoing account of the habits and characteristics of the woollj^ 

 aphis will enable us to suggest certain measures to control it. The 

 aerial form presents no especial difficulty, and can be very readily exter- 

 minated b}^ the use of any of the washes recommended for aphides, 

 such as kerosene emulsion, a strong soap w^ash, resin wash, etc., the 

 only care necessary being to see that the wash is put on with sulhcient 

 force and thoroughness to penetrate the covering and protecting cot- 

 tony excretion. If the wash be applied warm, its penetration will be 

 considerably increased. 



The much more important root form, however, is more difficult to 

 reach and exterminate. Any of the remedies which are applicable to 

 the phylloxera will apply to the apple root-aphis, such as the use of 

 bisulphid of carbon or submersion. The common recommendations 

 are of applications of strong soap or tobacco washes or kerosene emul- 

 sion to the soil about the crown, or soot, ashes, or tobacco dust buried 

 about the roots , also similarly employed are lime and gas lime. 



The most generall}^ recommended measure hitherto is the use of hot 

 water, and this, while being both simple and inexpensive, is thoroughlj' 

 effective, as has been demonstrated by practical experience. Water at 

 nearly the boiling point may be applied about the base of young trees 



