INSECTS IXJUKIOUS TO SHADE TREES. 



81 



Fig. 33. A soft scale as it appears on badly-infested twigs. 



Remedial Measures. 



About the only really satisfactory application is undiluted 

 crude petroleum as a winter spray. The miscible oils di- 

 luted no more than ten times, may answer the purpose; but 

 have not been sufficiently tested. Whale-oil Xot often 

 soap at the rate of 1 pound in 4 gallons of water J"nfui. 

 applied just after they are hatched will kill the young, and 

 this sort of application is feasible on small or moderate sized 

 trees. On very large trees only the winter applications are 

 at all practical. Fortunately this insect has some very ef- 

 f( crive natural checks which usually control it, so that except 

 on young trees we need not often apply treatments. 



OTHER SCALES. 



There are a variety of other scales, mostly allies of those 

 already mentioned, that at times infest shade trees, but rarely 

 in sufficient numbers to require active treatment. As a rule 

 winter treatments should be made if the species permits, for 

 there is not at that season any interference of foliage and 

 much stronger mixtures can be used on dormant trees. 



G 



