144 BULLETIN 190, UNITED STATES NATIONAL MUSEUM 



(1917 and 1936, Engelhardt) ; on the Snake River near Pullman, Wash, 

 (1935, J. F. G. Clarke). Specimens from Bowman, N. Dak., June 24, 

 1935 (Geiszler), and from Hamilton County, Kans., 3,350 feet (F. H. 

 Snow), are typical examples. 



PARANTHRENE ROBINIAE form PERLUCIDA (Busck) 



Plate 27, Figure 161 



Memythrus perlucida Busck, Proc. Ent. Soc. Washington, vol. 17, p. 80, 1915. 

 Paranthrene perlucida McDunnough, Check list of the Lepidoptera of Canada and 

 the United States of America, pt. 2, No. 8803, 1939. 



Male. — Antennae reddish brown, bipectinations blackish. Labial palpi 

 bright yellow, shaded with red at bases. Head on top, face, and occipital 

 fringe reddish brown. Collar transversely banded with black and yellow. 

 Thorax dark chestnut-brown, edged transversely with yellow posteriorly. 

 Abdomen reddish brown, with narrow and broad yellow annulations, 

 subject to variation ; segment 2 narrowly edged with yellow above, broader 

 beneath ; segment 4 yellow, slightly reddish anteriorly ; segments 5, 6, 

 and 7 usually exhibiting a tendency to lighter colors and yellow edges ; 

 segments 3, 5, and 6 narrowly ringed with black at posterior edge; anal 

 tuft short, narrow, yellowish. Legs chestnut-red, tarsi reddish yellow. 

 Forewing brown, suffused with red ; short vitreous streaks before reddish 

 discal mark and toward apex ; costa and veins bluish black, fringes dull 

 black; underside of a lighter tone. Hindwing transparent, glassy blue; 

 narrow margin reddish brown, fringes dull black ; discal mark and veins 

 red, touched with black. 



Female. — Abdomen reddish brown, except segment 2, which is nar- 

 rowly edged with yellow and segment 4, which is yellow, barely touched 

 with reddish on anterior edge. Otherwise like the male. 



Food plant.— Popuhts trichocarpa. 



Distribution. — Northern Rocky Mountains, Montana, Alberta, British 

 Columbia. 



Type.—V.S.'^.M. No. 19223. Female. 



Remarks. — The color form perlucida is represented by a large series 

 from Missoula, Mont., June 1914, reared from Populus trichocarpa 

 (Joseph Brunner) ; a female from Seton Lake, Lillooet, British Columbia. 

 June 30, 1906; a male and a female from Victoria, British Columbia (E. 

 H. Blackmore) ; and a small series from Calgary, Alberta, June 1923 

 (George Salt). 



PARANTHRENE ROBINIAE PALESCENS. new form 



Plate 27, Figure 162 



Male and female very pale, straw colored. Thorax light reddish brown, 

 transversely and at the sides posteriorly marked with pale yellow. Ab- 

 domen with segment 1 pale brown ; segment 2 pale brown and yellow in 



