CLEAR-WING MOTHS OF FAMILY AEGERIIDAE 143 



brush on top black and yellow mixed, face yellow, occipital fringe yellow. 

 Collar covered with depressed scales, black above and yellow below. 

 Thorax metallic black ; a yellow patch at wing base above and beneath : 

 tegula yellow, posteriorly uniting with a transverse yellow band on meta- 

 thorax to form a semicircular mark. Abdomen mostly yellow ; segment 

 1 all black, segment 2 ringed with black and yellow ; segment 3 banded 

 with black and yellow above and entirely black beneath ; segments 4, 5, 

 6, and 7 entirely yellow : the black on segments 2 and 3 sometimes blending 

 into chestnut or red ; anal tuft short, narrow, yellow. Legs with coxae 

 and femora black ; tibiae yellow, touched with black beneath ; tarsi deeper 

 yellow. Forewing suffused, ochreous or luteous, with or without vitreous 

 streaks between the veins before and behind the more densely scaled discal 

 mark; a yellow spot at wing base; the costa, veins, lower margin and 

 fringes blackish brown ; underside brighter and discal mark light yellow. 

 Hindwing transparent, discal mark conspicuous, deep yellow ; veins and 

 narrow margin ochreous, fringes dark brown. 



Female. — Considerably larger than the male in average size ; antennae 

 simple, deep yellow or orange, darkening before the tips. Forewing more 

 reddish. Otherwise like the male. 



Expanse: Male 26 to 30 mm., female 30 to 36 mm. 



Distribution. — West of the Mississippi Valley ; Rocky Mountain and 

 Pacific Coast States. 



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



Remarks. — In the western half of the United States and Canada. 

 Paranthrene robiniae replaces Paranthrene dollii, which represents the 

 eastern parts. The two species are closely related, structurally and bio- 

 logically, sharing the same food plants and having similar habits. Their 

 chief difference lies in the consistently transparent hindwings of robiniae 

 and the equally consistently suffused hindwings of dollii. Transitions 

 are not known. Both species respond to climatic changes in about the 

 same degree. The color form perlucida, from INTontana, Alberta, and 

 British Columbia, expresses the northern range of robiniae and palescens, 

 from extreme desert regions in California, the southern range. P. robiniae 

 prevails throughout the Western States from the Rocky Mountains to 

 the Pacific coast and from sea level to near timber line. The insect has 

 proved injurious to .shade trees, principally poplars and less so to willows. 

 Many young poplars were reported killed at vSacramento, Calif. (B. G. 

 Thompson, 1921"). Long series have been obtained at San Bernardino 

 and the Arroyo Seco. Los Angeles, reared from willow sections small 

 enough to cut with a pocket knife. A series from the Grand Canyon. 

 Ariz., is of interest because of the color variations displa^^ed, specimens 

 from the rim, at an elevation of 7.000 feet, being darker and having the 

 abdomen banded with black, while specimens from the inner canyon, 4.000 

 feet above sea level, are lighter and have reddish-brown abdominal bands. 

 Heavv infestations were encountered at Salt Lake Citv and Provo. Utah 



