30 INSECTS AFFECTING VEGETATION 



The woolly-aphis sucking the juices from the roots of the apple 

 tree causes an abnormal growth of the attacked portion of the roots 

 resulting in the formation of gall-like swellings or excrescences. 

 These swellings are usually irregular and knotty in appearance and 

 sometimes attain considerable size, while that portion of the roots 

 between the excrescences is frequently undeveloped. 



After planting, if the trees be kept in vigorous growing condi- 

 tion by careful cultivation and, if necessary, proper fertilizing, dam- 

 age from the aphides is much less apt to occur, and the principal 

 danger period, namely, the first two or three years after planting in 

 the orchard, will pass in safety. The value, as a means of protec- 

 tion, of thorough cultivation and good care of young orchards can 

 not be too strongly insisted upon. Vigorous growing trees have a 

 decided power of resistance and are able to sustain with compara- 

 tively little damage the presence of the root-aphides, while illy-cul- 

 tivated and neglected orchards are especially liable to injury. 



In planting apple trees tobacco dust should be freely used 

 among and over the roots, and close around the trunk, in order to 

 kill and prevent the woolly-aphis from establishing itself there. 



The root form of the woolly-aphis may be cheaply and easily 

 killed and kept away from an apple tree by the liberal use of to- 

 bacco dust. About five or six pounds of this substance should be 

 applied as above directed to the roots of every infested tree, and one- 

 half this amount should be applied in a similar manner each suc- 

 ceeding spring, costing approximately two cents per tree per year. 



The other sprays may be used after the trees are in full leaf 

 in the following proportions: Kerosene emulsion that is one-fif- 

 teenth kerosene; fish oil and whale oil soaps in the proportion of 1 

 pound to 8 gallons of water, and tobacco decoction in the proportion 

 of 1 pound to 4 gallons of water. (Col. E. S. B. [Press] 31; Mo. 

 E. S. B. 35; Dep. of Agr. B. of E. Cir. 20.) 



The Round-Headed Apple-Tree Borer. The first intimation 

 that the grower may have of the presence of this borer in his trees, 

 unless he be forewarned, is in their retarded growth and the saw- 

 dust-like castings, consisting of excrementitious matter and gnawn- 

 ings of woody fiber, which the larvae extends from the openings 

 into their burrower. The parent of this borer is a beautiful beetle, 

 measuring from three-fourths to nearly an inch in length. The 

 upper surface is light yellowish brown with two longitudinal white 

 stripes extending 'through the thorax and elytra or wing-covers to 

 the tip. The larva, when mature, measures from three-fourths to 

 a little over an inch in length. This borer is practically limited 

 in its food to the apple and kindred woody plants. It is most in- 

 jurious to quince and apple, and somewhat less so to pear. This 

 species inhabits more particularly the base of the trunk of trees, 

 often being found below the surface of the earth, especially in 

 young nursery stock. The larvae, soon after hatching, tunnel under 

 the bark and feed on the sap-wood, gradually working their way 

 upward and afterwards downward, usually remaining withjn a 

 short distance of. or below the surface of the ground, particularly 



