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Bureau of FAR^[ERs' Institutes. 



successful only in places where the infestation is very limited. 

 If but few trees are infested and there is no danger of its being 

 in nearby localities, it would be far wiser promptly to destroy 

 everything bearing the scale and start anew, rather than at- 

 tempt to save the trees. An infestation of considerable extent 

 can hardly be fought otherwise than by repeated treatments with 

 contact insecticides. Whale oil soap has proved about as effec- 

 tual as any, though the mechanical kerosene emulsion has been 

 strongly endorsed by some. Perhaps the most promising treat- 

 ment is found in the use of a 20-per-cent. mechanical emulsion of 

 crude petroleum applied in. early spring before the buds start. 

 There is no doubt of its killing a large proportion of the scales. 

 There is less danger to the fruit buds if winter treatment be de- 

 layed till early spring and if crude petroleum emulsion be used, 

 the viscid residue remains sometimes on the limbs and trunk and 

 is very unfavorable to the establishment of young scales. Crude 

 petroleum cannot be applied to leaves but it is said to injure 

 only growing wood, even in summer. Its use undiluted cannot 

 be recommended at present. The summer treatment with other 

 contact insecticides consists of several sprayings from when the 

 young begin to appear, sometime in June, till late fall. The fre- 

 quency of the spraying should depend largely on the abundance 

 of the young. The summer work is usually supplemental to the 

 winter operations. The formulas of contact insecticides for 

 either summer or winter use are given on a subsequent page. 



The following catalogue, descriptive of the insects in a small 

 traveling collection of the more important species, was prepared 

 by the State Entomologist and published in a convenient pocket 

 form for distribution at farmers' institutes: 



Fruit Tree Insects. 



1 Apple tree tent caterpillar {Clisiocampa americana). Conspicuous web 

 tents in forks of apple and cherry trees contain hairy caterpillars with a 

 white stripe along the back. Cocoons spun the last of May, the light 

 brown moths flying in June. Eggs, in belts encircling the smaller twigs, 

 remain unhatched till spring. 



Treatment: remove and destroy eggs or young in nests. Spray foliage 

 of infested trees with poison in early spring. 



