116 BULLETIN 190. UNITED STATES NATIONAL MUSEUM 



honeycombed by larval galleries, and higher up on the tree trunks the 

 larvae were boring under the bark to an extent calling for control 

 measures. 



The young saplings of the American chestnut, periodically produced 

 as sprouts from underground roots and representing about all that re- 

 mains of a formerly magnificent forest tree, invariably succumb in a few 

 years to the fatal attacks of the chestnut blight. From cuttings of parts 

 distorted by this disease I have reared scitula but never any of the original 

 chestnut bark borer, Synanthedon castaneae (Busck). On dogwood, 

 Cornus florida, scitula is common on scarred tree trunks. From cherry, 

 apple, mountain-ash, hickory, willow, and birch there are occasional records, 

 usually associated with injured or diseased places on the tree trunks. 

 Wounds and scars started by other insects also serve as abodes, regardless 

 of the kind of tree or shrub on which they occur. 



Rearings have been obtained from bayberry (Myrica carolinensis) 

 and from Japanese dwarf pine at Mobile, Ala. ; from hazelnut in Con- 

 necticut ; from white oak, Brooklyn, N. Y. ; from bark of Physocarpa, 

 Chicago, 111., and from rattan-vines {Berchemia scandens), Jacksonville, 

 Fla. This should suffice to indicate the variety of trees and shrubs sub- 

 jected to attacks when suitable ecological conditions are present. As' 

 may be expected, scitula is the commonest of the North American species 

 of Aegeriidae. Economically the most serious damage is caused to pecan 

 in the Southern States. Otherwise the species is not of great importance. 



The principal time of emergence is spring and early in summer, as 

 early as March in the South, but occasional adults issue through July 

 and August, and even as late as September. Whether this signifies two 

 broods in one year is difficult to prove. The change from larva to pupa 

 takes place in an oblong cocoon within the larval gallery. 



THAMNOSPHECIA SCITULA race CORUSCA (Hy. Edwards) 



Plate 25, Figure 153 



Aegeria coimca Hy. Edwards, Papilio, vol. 1, p. 193, 1881. 



Sesia corusca Beutenmuller, Bull. Amer. Mus. Nat. Hist., vol. 8, p. 140, 1896; 



Mem. Amer. Mus. Nat. Hist., vol. 1, pt. 6, p. 299, 1901. 

 Synanthedon corusca McDunnough, Check list of the Lepidoptera of Canada and 



the United States of America, pt. 2, No. 8733, 1939. 



Field investigations over a number of years have established beyond 

 doubt that corusca represents the southern extension in the range of 

 scitula, and hence it can be recognized only as a race. In structure and 

 in habits it agrees perfectly with typical scitula. It differs in having 

 coppery rays on the wing margins and orange abdominal bands instead 

 of yellow as in scitula. The change in coloration is gradual from the 

 coastal regions of Virginia southward into Texas. Inland, in hilly and 

 mountainous country, the color changes are less pronounced. 



Type. — Male. In the American Museum of Natural History. 



