THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 13 



NATURAL ENEMIES. 



In spite of its long larval period the tobacco Crambus does not 

 seem to be largely parasitized, at least during the later stages, this 

 being due presumably to the subterranean habits of the larvae and 

 the protection afforded by the loose web in which they usually lie 

 when not feeding. Nevertheless parasitic and predaceous enemies 

 are doubtless factors in keeping the insect in check. The vast num- 

 ber of newly hatched larvae as contrasted with the number found 

 later in the season shows that comparatively few survive the earlier 

 larval stages. This reduction is due in part to various natural ene- 

 mies the exact or relative importance of which it is hard to estimate. 



Various carabid beetles have been observed to feed on the larvae. 

 Among them were Calosoma calidum Fab. and Chlsenius tomentosus 

 Say. Adults and larvae of Harpalus (Harpalus pennsylvanicus De G. 

 and H.faunus Say) were observed to be very abundant about roots 

 of oxeye daisy and plantain which were heavily infested with 

 Crambus larvae. As the species of Harpalus are known to be gen- 

 eral feeders, they were thought to feed on the larvae of the Crambus. 

 The adults, when confined in tubes with larvae, occasionally fed on 

 them. 



Spiders of several species were observed to feed on the larvae, and 

 large numbers of the moths are captured in spider webs in weedy 

 fields. 



Ants also occasionally attack the larvae. An ant found carrying 

 a partly grown larva at Chatham, Va., was examined by Mr. Theo- 

 dore Pergande and found to be a species of Solenopsis. 



W. G. Johnson, in Maryland, reported the rearing of an undeter- 

 mined hymenopterous parasite from the larvae. No parasitic 

 Hymenoptera were secured from the rearing cages at Appomattox, 

 although large numbers of larvae were confined. 



Several Diptera were observed in cages containing larvae on vari- 

 ous occasions, but actual proof of parasitism was not obtained, 

 although a species of Phoridae was secured from tubes containing 

 larvae under circumstances pointing strongly to parasitism. 



In the National Museum are specimens of a hymenopterous para- 

 site, Perisemus prolongatus Pro v., labeled as reared from larvae of 

 Crambus caliginosellus from La Fayette, Ind. The record is doubt- 

 ful, however, as the notes concerning the specimens in the files of 

 the Bureau of Entomology clearly refer to a different species of 

 Crambus as the host. 



Birds are a factor in keeping the tobacco Crambus in check. Two 

 species, the quail (Colinus virginianus) and the kingbird (Tyrannus 

 tyrannus) were observed by the writer to capture the moths, and 

 others are known to feed freely on moths of this genus. F. M. Web- 

 ster states that the wood pewee (Myiochanes virens) was observed to 



