22 



BULLETIN 1238, IT. S. DEPARTMENT OF AGRICULTURE 



MOTH. 



The following description has been condensed from Biley (24-). 



Male (PI. Ill, B). — Wing expanse from 21 to 32 mm. Palpi very short, 

 but distinctly two-jointed. Antennae with not quite 40 joints, the longest 

 twice as wide as long, each with two pairs of hair fascicles. Abdomen with 

 first seven joints bearing each two transverse dorsal rows of stiff, reddish 

 spines, pointed posteriorly. Wings delicate, silky, semitransparent, transversely 

 striate, the scales short and very loosely attached. Upper surface of front 

 wings brownish gray, crossed by three jagged, dark lines, sometimes obsolete 

 except on the submedian and median veins, and on the costa, where they are 

 always distinct and divide the wing into four subequal parts. A pale, jagged, 

 subterminal band, corresponding in some degree to the outermost band in A. 

 pometeria, but running out to apex, where it is always sharply relieved pos- 

 teriorly by a dark mark, and often the whole length by dusky shadings. Hind 

 wings pale ash or very light gray, with a dusky discal dot. No white band, and 

 rarely any marginal dots. Under surface with a more or less distinct dusky 

 spot on each wing, the front wing having in addition a dusky line along 

 median vein and spot on costa towards apex. No pale bands. 



Female (Plate III, C). — Length 5 to 9 mm. Antennae generally with but 

 few more than 30 joints, the longest about three times as long as wide, 

 faintly constricted in middle, and pubescent. Body and legs pubescent, clothed 

 with whitish and brown or black dentate scales or hairs ; general coloration not 

 uniform. Crest of prothorax and mesothorax black. A black stripe along the 

 middle of the back of the abdomen, often interrupted on the 2d to the 7th seg- 

 ments, with a whitish patch each side of its front end. Abdomen tapering 

 rather acutely behind. Two rows of spines on back of the first seven joints, 

 more prominent than in the male, and often giving the dorsum a reddish aspect. 



SEASONAL HISTORY AND HABITS. 



EMERGENCE OF MOTHS. 



The moths of the spring species emerge in early spring, very soon 

 after the frost is out of the ground, and may occasionally leave the 

 ground when warm periods occur during mild winters. Table 9 

 gives data concerning the emergence of moths in 1920 and 1921. 

 Emergence in 1920 was from larvae collected in various stages in the 

 field the preceding spring and allowed to enter the ground normally. 

 The 1921 records are partly from similar material, and partly from 

 pupae obtained from insectary material and later placed in the cages. 

 Mortality was evidently high among the pupae in the ground during 

 the season of 1920-21, as evidenced by the extremely light emergence 

 in the spring of 1921, when only 9 moths emerged from 157 larvae and 

 pupae placed in the cages. 



Tabi.f 9. — Emergence of moths of the spring canker worm, Walttngford, Conn., 



1920 and 1921. 



IN 1920. 



Date. 



Emergence. 



Temperature. 



Remarks. 



Male. 



Female. 



Maximum 



Minimum. 



Average. 



Mar. 27 



1 





°F. 

 58 

 M 

 51 

 55 

 68 

 57 

 40 



°F. 

 39 

 35 

 35 

 36 

 38 

 36 

 35 



°F. 

 if., f 

 47.3 

 44. 5 



43. 5 

 50. 5 



44. 5 

 36.9 



Clear. 



Mfor. 28. 





Do. 



Ifar.29 



3 



1 



1 

 2 



3 



1 

 2 



Rain. 



Mar. 30 



Ifar.31 



A pr. 1 . . 



Clear. 

 Do. 

 Do. 



Apr. 2 





Rain. 



