86 BULLETIN 190, UNITED STATES NATIONAL MUSEUM 



black behind, tips black. Head black, orbits silvery white. Collar orange. 

 Thorax violaceous-black, with yellow scales on patagia in a broken ar- 

 rangement ; thorax beneath pale yellow. Abdomen above steel blue or 

 violaceous, segments 2, 4, 5, and 6 edged with pale yellow; beneath 

 segments 1 and 2 sprinkled with whitish scales and segments 4, 5, 6, and 

 7 wholly sordid white shading to pale yellow laterally ; anal tuft fan- 

 shaped, bluish black, mixed with red at the sides and end, beneath bright 

 red, black at the sides on upper part, and claspers yellow. Outer side 

 of femora, anterior part of tibiae and tarsi blue-black mixed with yellow 

 scales and tarsi banded with yellow at the joints ; posterior part of tibiae 

 between the spurs solid blue-black ; inner side of femora, tibiae, and 

 tarsi yellow, except for a blue-black area between the spurs, which are 

 yellow. Wings transparent ; costa, veins, rather broad apical margin, 

 and large discal mark of primaries metallic black ; hindwings with nar- 

 row black outer margins and brownish fringes ; underside of wings shaded 

 slightly with yellow scales on costa and veins. 



Female. — Apical third of antenna contrastingly shaded with sordid 

 white or pale yellow on upper surface. Abdominal segments often, but 

 not always, dusted with pale-yellow scales in addition to having narrow, 

 pale-yellow bands on segments 2, 4, and 6; segments 4, 5, and 6 be- 

 neath sordid white ; anal tuft short, rounded, wholly bright red. Other- 

 wise like the male. 



Expanse : Male 16 to 18 mm., female 18 to 22 mm. 



Distribution. — Eastern half of the North American Continent from 

 the Atlantic coast to Canada. 



Type. — Male, in the United States National Museum. 



Remarks. — Red and sugar maples are the native food plants of 

 acerrubri, but other maples, especially when planted as shade trees, also 

 are attacked. The larvae bore. under the bark, preferring branches to 

 tree trunks. When a larva is working singly it causes a slight swelling 

 or a roughening on the branch. Quite often advantage is taken of wounds 

 and scars caused by the borings of other insects, beetles of the family 

 Cerambycidae and Buprestidae and of the leopard moth, Zeusera pyrina 

 (Linnaeus), which has become a serious pest to various shade trees 

 in the neighborhood of New York City and on Long Island. Such 

 scars may harbor six or more larvae of the aegeriid borer, thereby 

 contributing to the injury. C. acerrubri is an annual species ; the larva, 

 wintering in its burrow, resumes feeding in spring before changing to 

 a pupa within an oblong cocoon of castings and chip^ in a cell just 

 under the bark, with a thin, circular shell remaining' to be broken by 

 the pupa upon emergence of the moth during late May and June. 



C. acerrubri is not so common a species as the other maple-infesting 

 aegeriid, Sylvora acerni. Serious outbreaks usually are local. While 

 somewhat resembling acerjii in appearance, it is structurally quite distinct. 



