THE HORNED SQUASH BUG. 29 



other well-known enemies of Cucurbitacre, and they undoubtedly con- 

 tributed their quota that year toward injuring- these crops. On the 

 last date mentioned tbey outnumbered all of the other insects, although 

 the cucumber beetle was present in such numbers as to have left large 

 holes in every leaf that could be seen. After the end of September no 

 more specimens could be found, as cucumbers were mostly turned 

 under and the stems and leaves of squashes and similar plants were 

 dried up. 



The first observed date of the occurrence of this species in the neigh- 

 borhood of the District of Columbia was July 8. On this day of 1898 

 the writer found specimens on the experimental plats of cucurbits on 

 the grounds of the Department of Agriculture, and Mr. Pratt took one 

 at Poolesville, Md. Subsequently other individuals were found on the 

 experimental plats, and it is probable that these were the offspring of 

 a number that were left on the Department grounds in September of 

 the previous year. It is quite positive now that this species is widely 

 and generally distributed in Maryland and Virginia within a few 

 miles of Washington, and to be found here almost wherever cucurbits 

 grow. Since the first capture of this species in 1897 it has been found 

 on cucurbits wherever sought for. 



July 16 it was observed in abundance at Marshall Hall, more indi- 

 viduals of this species being seen than of A. tristis. It was apparently 

 more abundant than the latter species, but this was probably not the 

 case, as the latter, although nearly always to be found at the same time 

 with it, is less active than armigera and not usually seen in the heat of 

 the day. The greater activity of armigera was quite noticeable on this 

 day, numerous individuals being seen in flight and freely exposed on 

 the upper surface of the leaves, while tristis, when seen at all, was 

 usually on the edge of a leaf concealed beneath the leaves or under 

 debris in the immediate vicinity of cucurbit plants. The greater 

 abundance of tristis as a whole in localities inhabited by both, the 

 writer believes, may be accounted for, partially at least, by its darker 

 color and less active diurnal habits. Armigera is particularly conspic- 

 uous when flying, as the upper surface of the abdomen exclusive of the 

 connexivum or sides is bright orange, and this gives the principal col- 

 oring to the insect itself when in flight. 



The dorsal surface of the abdomen of tristis is black, but occasion- 

 ally this part is colored, as one individual captured shows a bright red 

 interior. 



July 29 nymphs of this species were found on cucumber at Cabin 

 John, Md., as also on cantaloupe, but were rare on both plants. Ko 

 squash grew in the vicinity. 



This squash bug was never received through correspondence till 

 August 3, 1898, when Mr. Henry J. Gerling sent specimens from St. 

 Charles, Mo., with the accompanying information that they travel along 

 the cucurbit vines, u taking an inactive position on either leaves or 

 vines for some time." They were not detected in the act of feeding, as I 



