THE CANKERWORMS 11 



PUPA. 



Stout, 7 to 10 millimeters long. General color greenish brown, wing pads 

 more greenish, margins of the segments a deeper brown. Surface without 

 spines, somewhat finely punctate. Anal segment with a stout curved spine, 

 terminating in a pair of curved bristles (PI. II, C, F). 



MOTH. 



The following description has been condensed from Riley (24) ' 



Male (PI. II, D). — Expanse of wings 26 to 34 mm. Palpi rudimentary with 

 joints indistinguishable. Antennae with over 50 joints, the longest not twice 

 as long as wide, each with one pair of fascicles of slightly curled hairs. 

 Abdomen without spines. Wings less transparent, more glossy than those of 

 P. vemata, not striate, the scales on the average longer and more firmly at- 

 tached. Upper surface of front wings brownish gray, but somewhat darker, 

 with a purplish reflection, crossed with two jagged, whitish bands, the outer- 

 most suddenly bending inward near costa, where it forms a pale, quadrate 

 spot, relieved by a darker shading of the wing around it ; the bands some- 

 times so obsolete as to leave only this pale spot; but more often relieved on 

 the sides towards each other by a dark shade, most persistent on the veins. 

 Hind wings grayish brown, with a faint blackish discal dot. In most specimens 

 a curved white band runs across the wing, and the veins inside this band and 

 on the hind border are generally dotted. Under surface with a dusky discal 

 spot on each wing, and with the outer pale band on upper surface of front 

 wings as well as that of the hind wings showing distinctly, the former relieved 

 by a dusky spot inside at costa. 



Female (PI. II, E, G). — Length 6 to 10 mm. Antennae with over 50 joints, 

 the longest hardly longer than broad ; uniform in diameter, without pubescence. 

 Body and legs smooth, clothed with glistening brown and white truncate scales 

 intermixed, giving it an appearance of uniform, shiny, dark ash gray, some- 

 what paler beneath. Abdomen tapering rather bluntly behind, without spines. 



SEASONAL HISTORY AND HABITS.. 



The following observations, recorded largely in the insectary, 

 were carefully compared with field conditions, and were found to 

 agree very closely. 



EMBKYONIC DEVELOPMENT. 



The development of the larva within the egg is apparently not 

 completed until a few days previous to hatching. When fully de- 

 veloped, the larva lies doubled, with head and anal extremity near 

 together just beneath the cap of the egg. 



HATCHING OF THE EGGS. 



In the vicinity of Wallingford, Conn., in a normal season, the eggs 

 hatch early in May, beginning as the apple blossoms of midseason 

 varieties are showing pink, and ending before they have opened. 

 In 1918 hatching began May 4; in 1919 on May 1; in 1920, which 

 was a very cold and late season, on May 11, and in 1921, an abnor- 

 mally early season, on April 16. The relation between the stage of 

 development of the apple buds and the hatching of the cankerworms 

 was approximately the same each year. Hatching in a given locality 

 may extend over a period of 12 days, depending on weather condi- 

 tions, but ordinarily the greater part of it occurs within 4 or 5 days. 

 With individual egg clusters, most of the hatching is completed 

 within 2 or 3 days after the first egg hatches. 



Table 2 gives a summary of the hatching records of 31 egg masses 

 collected in the field in 1919 and 6 egg masses collected in 1920. 



