12 BULLETIN 1076, U. S. DEPARTMENT OF AGRICULTURE. 



terminecl by Gahan). The parasitic grubs to the number of about a 

 dozen emerge from their host larva shortly before time for the pupa- 

 tion of the latter. They then spin a mass of brown silk cocoons so 

 tightly compacted that it is difficult even to determine their number. 

 This mass is found in the burrow or partially constructed cocoon of 

 the host. In more than one instance adults of this parasite were found 

 well within the larval burrow of the host, evidently hunting opportu"- 

 nities for oviposition, but it is not known just how or at what age the 

 host larvse are attacked. 



In three instances Chalcis ovata Say (det. Rohwer) was reared 

 from the pupse by the authors. 



The authors found but one case of egg parasitism. One egg mass 

 was taken which appeared darker than normal. When retained in a 

 vial, part of the eggs hatched normally, but the rest, which had 

 meanwhile turned jet black, gave forth adults of Triclio gram/ma 

 mvlnuturn Riley (det. Gahan), one from each egg. 



SCAVENGERS. 



Very often small dipterous maggots were found in the empty bui . 

 rows or feeding on decaying larvas or pupse. A number were reared, 

 and two species of flies were obtained, ApMochaeta chaetoneura 

 Malloch (det. Greene), and ElacJiiftera nigvice'ps Loew (det. Al- 

 drich). These were undoubtedly scavengers, and nothing was ob- 

 served to indicate that they were in any way injurious to sound 

 larvae or pupse. They seem to thrive equally well on putrid vege- 

 table matter. Coquillett (8) mentions rearing the latter of the two 

 species from the same situation many years earlier. 



OTHER ENEMIES. 



A somewhat j^eculiar catastrophe was found to happen very often 

 to the larvae which had prepared their pupation chambers in the 

 upper end of the petioles of the floating leaves. Some animal, evi- 

 dently, took a bite out of the side of the petiole close under the leaf, 

 thereby cutting into the cavity and its occupant. In some such cases 

 the cut-out portion of the petiole was left hanging, in others it was 

 gone, and often the predator had bitten the petiole entirely off at 

 this point. No portion of the larvae or pupae was ever found in the 

 cavity, and the work was very evidently done intentionally in search 

 for the insect. Often uninfested petioles were cut, evidently by 

 mistake. The possible authors of the work were (1) ducks, a small 

 flock of which frequented the pond; (2) frogs, of which there were 

 many, some of them very large; (3) fishes; and (4) turtles. The 

 character of the work eliminates the ducks and frogs because their 

 jaws are not sufficiently strong to make such clean cuts as these were. 

 No direct evidence of the presence of fish was found, and in such 



