CROP PEST COMMISSION OF 



egg is laid; when the larva hatches it is fed on flies which she 

 Cotches and carries to it. Many suppose, when they see this 

 handsome insect flying around horses or cattle, that it is catch- 

 ing food for itself, but in this I suspect they are mistaken, 

 i ? or it is my opinion that the adults feed on the nectar of flowers, 

 011 honey-dew from plant-lice and scale-insects and the like, far 

 they commonly visit flowers of various kinds, and they were ob- 

 served in abundance crawling over the leaves and branches of 

 j rickly ash trees thoroughly infested with a common scale- insect 

 (Ceroplastes cirripediformis) . My belief is that they visited these 

 trees for the purpose of procuring for food the sweet substances 

 which the scale-insects secreted. 



It is most interesting to take a position in the midst of a 

 nesting colony of this species and watch the procedure. At first 

 many of the wasps may be seen flying actively on every side, 

 then when all is quiet they settle down to regular routine ; some 

 run rapidly over the ground as if searching for the location of 

 their nests, others are making new burrows or cleaning out old 

 ones, while still others appear upon the scene from time to time, 

 <sch carrying a fly which she takes into her nest as soon as the 

 latter is located and she has satisfied herself that the way is 

 clear. Often a wasp drops her fly for a time, makes an investiga- 

 tion of the surroundings, and then returns and picks it .up again. 



It appears that when horseflies are to be had the young are 

 led on them altogether, and as these flies are caught around ani- 

 mals, it is almost always the female, or biting sex, which is 

 taken. The larvae make way with all the soft parts of the flies, 

 but the wings, and very often the head, and more or less of the 

 outer covering are not devoured, so are found in the larval 

 chambers with the immature stages of the wasp. By making a 

 -count of the wings of horseflies and other species taken from a 

 single burrow the number of specimens that have been carried 

 into that particular burrow can be determined, presumably with 

 s reasonable amount of accuracy; at any rate, the number can 

 uot be overestimated in this manner. The following are records 

 <}' the counts of material taken from a number of nests: 



On July 1 a colony of horse guards was located near the 

 -gulf, about a mile to the eastward of the Biologic Station build- 

 ing, and some larvae procured from burrows. 



