E-18S. 



K C EI v^D 



UNITED STATES DEPARTMENT OF AGRICULTURE , > 923 <*> 



BUREAU OF ENTOMOLOGY 

 WASHINGTON, D. C. 



FOREST ENTOMOLOGY BRIEF 46. 



July 14, 1919. 



THE EUROPEAN ELM SCALE 

 (Gossyparia spuria (Modeer)) 



History and Damage.- This insect, an immigrant from Europe in about 

 1884, lives on elm trees only and may occur wherever this tree is 

 grown in the United States. As a rule it does not kill the trees 

 but it is often so very injurious, especially to young stock, that, 

 together with the injury caused by the elm leaf -beetle, another im- 

 portation from Europe (see Forest Entomology Brief 39), attack by 

 bark borers, etc., is »«duced and the trees do not recover. 



How it Lives and Looks. - Like others of its kind this scale insect 

 feeds on sap which it sucks from the bark of the trunks and twigs 

 or leaves by means of a slender, thread-like beak. The winter it 

 spends in crevices of the bark on the trunk and larger branches as 

 brown immature males and females imbedded in white cottony matter. 

 - On the appearance of warm weather, in May at Washington, D. C, 

 these forms begin to move about, molt, and mate, after which the 

 females attach themselves permanently on limbs and trunk. The 

 young - clear, lemon-yellow, lice-like insects - issue during June 

 and July, settling temporarily on leaves alone or on leaves and 

 twigs, depending on the smoothness of the latter. In August they 

 return to the larger branches and trunk to settle for the winter, 

 thus completing in Washington the seasonal life cycle. 



Remedies. - In the case of shade trees and nursery stock, the best 



means of killing this insect is to spray infested trees during the 

 dormant season with a 7 per cent solution of miscible oil in water, 

 applying it like kerosene emulsion, as described in the companion 

 Brief. Spraying with a summer strength of such an oil while the 

 young are hatching is the next best means of control, Miscible 

 oil is procurable in seed stores under various proprietary names. 

 Other means of destroying the insect are available, such as water 

 applied with a hose under high pressure, but none are as satis- 

 factory as the solutions mentioned. 



A. D. Hopkins, 



Forest Entomologist 



