5-2 



as indicated below, the larvae were taken quite abundantly, destroy- 

 ing the locust eggs later in the season. Small red mites, which are 

 frequently seen attached to the bodies of the mature locusts, are 

 also of beneiit, in that while young they suck the life-juices of the 

 locusts, and, later, puncture their eggs and extract the contents. 

 These were rather numerous in the infested regions. The larvse of 

 the common black ground beetles {Carabidre) which are, to a great 

 extent, carnivorous, also feed upon the eggs, and, ns they are every- 

 where abundant, contribute not a little to lessennig their numbers. 

 Certain species of two-winged Hies (DijJtera) are also known to be para- 

 sitic upon the eggs as well as the adults, and there were indications 

 that some of them, at least, were at work in Peoria and Knox 

 counties the past season. The white hair-wonns (Mennis), which 

 also infest grasshoppers, were found by Prof. Forbes, in the sum- 

 mer, "unusually numerous in the sod," though he had not "seen any 

 evidence that they appreciably diminished the number of grass- 

 hoppers." 



The following account, as given in my notes, of the investigation 

 of the situations in which the eggs were laid and the extent to 

 which they had been destroyed during the autumn of 1885, on Mr. 

 Davis's farm, may be of interest as indicating the positions from 

 which the young locusts will emerge the coming season, and the 

 condition in which the eggs were at the beginning of winter. 



The first field examined was the pasture on which the locusts 

 had been so numerous that a considerable portion of clover had 

 been killed, root and branch. In searching for the eggs, which are 

 deposited about an inch below the surface of the soil in masses or 

 pods, each of which contains a number of eggs varying from a dozen 

 to fifty or sixty or even a hundred, a short strip was plowed, to a 

 depth of about one inch and the sod thus inverted was broken up 

 bit by bit, a careful record of the number of egg-masses found being 

 kept, and the eggs themselves, together with any predaceous, i^ara- 

 sitic, or other insects that were discovered, were bottled in alcohol. 

 All facts that could have any bearing on the subject, such as sit- 

 uation in the field, the number and species of insect enemies, or 

 the proportion of eggs destroyed, were also recorded. The first 

 plowing on the highest portion of the pasture turned up about 27 

 square feet of sod, in which nine egg pods were found, a portion of 

 them having been destroyed by insect enemies. In one of the pods 

 was a living larva of one of the blister beetles [Meloidce), which had 

 already devoured about half of the eggs, and was rapidly making 

 way with the rest. Several red mites, which are supposed to prey 

 upon locust eggs, were found, as were a few of the predaceous lar- 

 vae of the Carahidcs or ground beetles. At the second plowing, 20 

 square feet were inverted, revealing four egg masses, two meloid 

 coarctate larvae, and two carabid beetles. Next, 15 square feet were 

 overturned, seven egg pods being found, four of which had been 

 destroyed ; and one meloid coarctate larva was taken. Another strip of 

 the same size as the last, midway between the highest and lowest 

 part of the pasture, yielded six egg masses (one of which was de- 

 stroyed) two red mites, and one meloid larva. The rest of the plow- 

 ing was in the lowest portion of the field, which was well under- 

 drained and perfectly dry. The soil here was black and loamy. 



