THE CANKER WORMS 31 



fall and spring species, respectively, collected near Wallingford 

 during the spring of 1919. 



Rogas sp. — Occasionally third-instar larvae of the fall canker- 

 worm were found near Wallingford parasitized by a species of 

 Rogas, their dried and shrunken skins serving as shelters for the 

 parasite pupae. Harrington (25) reports finding a number of larvae 

 in a similar condition, but all were infested with secondary parasites, 

 determined as Hemiteles sessilis Prov. 



Euplectrus sp. — One third-instar fall cankerworm larva was 

 found near "Wallingford on June 5, 1919, collapsed and doubled over 

 a greenish parasite larva which was constructing its cocoon. The 

 adult parasite emerged two weeks later. Payne (37) reports from 

 Nova Scotia the rearing of a species of Euplectrus, and Sherman 

 (39) also reports a species of the same genus from the fall canker- 

 worm from North Carolina. Both of these may be the same and 

 identical with the parasite reared at Wallingford. 



Amblyteles utilis Cresson. — Amblyteles utilis has been recorded as 

 a parasite of cankerworms (35, p. 359). 



Apanteles paleacritae Riley. — This species was described by Riley 

 (21) as a parasite of the spring cankerworm and reported by Har- 

 rington from the fall species. A single adult of this species was 

 reared by Dwight Isely, of the Bureau of Entomology, in May, 

 1918, at Bentonville, Ark., from a larva of the spring cankerworm. 

 It is said that the host larva does not die until some time after the 

 emergence of the parasite larva, which spins its cocoon on its host 

 or a near-by leaf. 



Tachinomyia sp. — Fourth-stage and sometimes third-stage larvae 

 of the fall cankerworm are sometimes found bearing on the head 

 or prothorax one or more oval, flattened, creamy white tachinid eggs. 

 On hatching, if the host larva has not molted in the meantime, 

 the parasite larva makes its way through the skin of the cater- 

 pillar, usually on or near the head, and takes up its position just 

 beneath. Parasitized larvae complete their development, enter the 

 ground, and commence the construction of their cocoons, but rarely 

 complete them before being killed by the parasite. Out of five 

 parasitized larvae entering the ground at Wallingford in the spring 

 of 1919, two flies emerged in May, 1920. These were determined by 

 Dr. J. M. Aldrich as a species of Tachinomyia, probably undescribed. 



Harris (9) mentioned a tachinid fly as a parasite of the canker- 

 worm in Massachusetts, causing a mortality of one-third. Many 

 other workers have mentioned tachinid parasites, but none seem to 

 have been reared and determined. 



Sarcophaga cimbicis Townsend or S. latisterna Parker. — This 

 species was reared by Sherman from the fall cankerworm in North 

 Carolina in 1920, and determined by Dr. J. M. Aldrich. 



OTHER ENEMIES. 



Goriarachne versicolor Keyserling. — Spiders determined by C. R. 

 Shoemaker, as this species were found near Wallingford feeding on 

 the spring cankerworm moths as they emerged. 



Nothrus omvorus Packard. — This mite was described by Packard 

 (13, p. 664, fig> 639) and recorded as having been observed in the act 

 of sucking the eggs of the fall cankerworm. As far as is known, this 



