24 PROCEEDINGS OF THE ACADEMY OF 



CURIOUS ANOMALY IN HISTORY OF CERTAIN LARViE OF ACRONYCTA 

 OBLINITA, GUENEE, AND HINTS ON PHYLOGENY OF LEPIDOPTERA. 



BY THOMAS G. GENTRY. 



In the autumn of 1813, numerous larvae of Acronycta oblinitawere 

 observed by the writer feeding upon the leaves of Polygonum 

 Pennsylvanicum. Their ravages were confined to a limited region, 

 in which a plentiful supply of their favorite food was found to 

 meet the most vigorous demands. Within a space of fifty feet 

 square, more than a hundred were counted. A diligent search 

 through the adjoining country failed to reveal any further traces 

 of them. As this species of weed is particularly prolific in Ger- 

 mantown, I had hoped to meet with other larvae of the same 

 species. Instances have occurred in the writer's experience, and 

 doubtless in the experience of others, of comparatively small 

 scopes of countiy yielding ample nourishment to hosts of larvae of 

 a particular species. This is usually noticeable among lepidop- 

 tera, which instinctively deposit their ova either in single clusters, 

 or in small collections but slightly isolated from each other. 

 Vanessa antiopa affords a familiar illustration of the foregoing 

 assertion. 



During the summer of 1867, I daily observed in a grove of red 

 maples a desperate encounter which a score of Calosoma scrutator 

 was waging against the harmless, though terrible-looking cater- 

 pillars of Vanessa antiopa. Although the destruction was on a 

 singularly grand scale, yet hundreds of larvae remained to undergo 

 their transformations during the latter part of August. The eaves 

 of the buildings in close proximity, fence rails, and in short nearby 

 every available place, were hung with the angular chrysalides. So 

 numerous were the latter, that after the final metamorphoses had 

 passed, the red fluid which was ejected by the tender and newly- 

 formed butterflies, gave everything the appearance of having been 

 profusely spattered with blood. 



The area subjected to the desolating influence of these larvae, 

 did not cover less than two acres of ground. It is worthy of re- 

 mark, that during the same summer this section of country was 

 unfortunately visited by legions of Cicada septemdecim. 



It is but occasionally in many years that unusual numbers of a 



