TREE INSECTS AND THEIR CONTROL 207 



twig will disclose the presence of the grub. 

 Trees often become badly deformed as a 

 result of this insect's work. 



SAP-SUCKING INSECTS 

 Oyster-shell Scale 



Habits This scale may be recog- 



and nized by its shape and appear- 



Damage. ance. In color it is brown or 

 grayish, and in form it is long 

 and curved, spreading at one end. It is 

 easily moved by prying beneath it with 

 a finger nail or knife-blade. The eggs are 

 laid in the fall and remain all winter under 

 the parent scale, encrusting the bark of a 

 branch. Hatching takes place about the 

 time apple-blossoms fall, and produces 

 crawling insects which thrust their sharp 

 beaks into the bark and feed on the sap for 

 several weeks, until maturity and repeti- 

 tion of egg-laying. Two broods a year are 

 developed even as far north as New 

 Jersey. 



Treatment. Nature provides for the 

 destruction of a large per- 

 centage of oyster-shell scales, through the 

 agency of enemy insects. It is unsafe, 

 however, to leave the work to these ene- 

 mies, and spraying is necessary for com- 

 plete elimination. The only time this 

 spraying is effectual is immediately after 

 hatching, shortly after the season at which 

 apple-blossoms fall, when the lice-like 

 insects are crawling, or have just inserted 

 their beaks into the bark. Whenever 

 these insects are visible they should be 

 sprayed with miscible oils (lime sulphur 

 hard on foliage), with kerosene emulsion, 

 or with whale-oil soap in the proportion of 

 one pound of soap to five gallons of water. 



Woolly Elm-bark Aphis 



Habits 



and 



Damage 



This insect causes more 

 damage to the looks of a tree 

 than to its growth. Its 

 attacks produce knotted and 

 gnarled twigs and trunks on young trees. 

 The American Elm is especially suscep- 

 tible. An infested tree shows the rough 

 knots, with clusters of white, woolly sub- 

 stance and lice-like insects. These insects 

 appear during the spring and summer, 

 and spend their entire lives on a single 

 tree. 



Remedies. The insect is easily con- 

 trolled by spraying with 40 

 per cent, nicotine sulphate, with kerosene 

 emulsion or with a solution (5 to 7 per 

 cent.) of one of the standard miscible oils. 

 The spray should be applied thoroughly 

 to the bark. If miscible oil is used the 

 spray should be applied in the winter 

 time; + he other should be used as needed. 



European Elm Scale 



Habits While not often the direct 



and cause of a tree's death, this 



Damage, sap-eating scale causes injur- 

 ies which, by weakening the 

 tree, lead to fatal attack by borers. The 

 scale winters in crevices of the bark on 

 the trunk and the larger limbs. At this 

 period its color is brown, and it is embed- 

 ded in a white substance resembling cot- 

 ton. With the approach of warm weather 

 eggs are deposited, and these hatch in 

 early summer, producing insects resemb- 

 ling lice. These insects have coloring of 



Remedies. Winter spraying is the 

 most effectual means of 

 destroying the scale. The spray should be 

 kerosene emulsion, or a water solution of 

 one of the standard miscible oils. Not so 

 effectual, but useful when needed, is 

 summer spraying with one of these pre- 

 parations during the hatching season, in 

 June or July. 



