1907.] The Cottony Maple Scale in Illinois. 357 



On the strength of these experiments Mr. Johnson recommends 

 an emulsion one sixth of which is kerosene. Trees treated with an 

 emulsion of this strength in the winter of 1904-05 were nearly free 

 from scales the following July, and in January, 1906, only scatter- 

 ing specimens could be found. In view, however, of the difference 

 in climate and the absence of data as to parasitism, these results 

 should not be regarded as conclusive for Illinois. 



Insect Enemies. 



It is to the insect enemies of the scale rather than to any human 

 agency that the escape of our soft maple trees from complete de- 

 struction has hitherto, been due. Probably the most effective enemy 



Fig. 6. Coccopliagits lecami, adult chalcid parasite of the r.ottoay maple scale. 

 • Length, less than i', inch. (J.B.Smith.) 



is a minute black four-winged fly (Coccophagus lecanii, Fig. 6) 

 which lays its eggs in the bodies of the young scales. The resulting 

 larva lives as an internal parasite of the insect, develops to the adult, 

 and emerges through a rounded hole cut in the back of the scale. Suc- 

 cessive generations follow, and the scale population of a heavily in- 

 fested tree may be almost completely destroyed in a single season 

 by the parasite. Scales killed by it may be readily recognized by 

 the hole in the back, and by their smaller size as compared with 

 living individuals. Several other related species are known to infest 

 this scale to a less degree. 



