INVESTIGATION OF LIFE HISTORY. 37 



died; 9 entered the ground and pupated, but 3 of these died in the 

 pupal stage, so that only 6 adults emerged. The amount of food 

 consumed was less than the amount usually eaten by a beetle larva 

 of this species and averaged 30 full-grown gipsy moth larvae. 



The result of this experiment shows conclusively that this species 

 suffers little if any from the "wilt." An examination of the rearing 

 records indicates that the percentage of survival in these experiments 

 compares favorably with that in those tests where healthy caterpil- 

 lars are offered for food. In fact it seldom happens that 90 per cent 

 of the larvae that hatch can be reared to the pupal stage in confinement, 

 and the loss of 30 per cent of the pupae is not surprising when it is 

 understood that pupation took place in jars containing only a small 

 amount of earth, which rendered the transformation very difficult. 

 The record of the feeding experiments of all the larvae of sycophanta 

 that hatched in 1907 shows that 15.5 per cent of the gipsy moth cater- 

 pillars furnished as food died from disease. 



In field colonies it is quite common to find Calosoma sycophanta in 

 localities where enormous numbers of gipsy moth larvae and pupae 

 are dying from the" wilt " disease, and frequently larvae of the Calo- 

 soma beetle are found feeding on the pupae and on the caterpillars of 

 the gipsy moth in masses which are badly diseased. Only one case, 

 has been observed of a dead Calosoma larva showing symptoms of 

 the "wilt" disease, and the evidence in this instance was not at all 

 conclusive. If the Calosoma beetles were susceptible, there is every 

 reason to believe that at least some of the field colonies would have 

 been practically exterminated by disease, but the results of repeated 

 examinations in the field show exactly opposite conditions. 



RESULTS OF FEEDING TO CALOSOMA LARV.E CATERPILLARS FROM SPRAYED OR POISONED 



AREAS. 



Owing to the practice of spraying for the purpose of controlling the 

 gipsy moth, a method which has come into very general use during 

 the past few years, fear has been expressed that the Calosoma beetles 

 or their larvae might be destroyed by feeding upon caterpillars that 

 had devoured the poisoned foliage. During the past two sum- 

 mers attempts have been made to test this matter in the labora- 

 tory, but in the season of 1909 this work had to be discontinued on 

 account of the large number of other experiments which was then 

 being conducted. 



In 1910 a series of experiments was planned — the idea being to 

 spray a small area of low growing sprouts in which gipsy moth cater- 

 pillars were abundant, and to feed these caterpillars to the larvae of 

 the Calosoma and keep a close record of the result. The experiments 

 were begun with the larvae of sycophanta which hatched June 30, 10 

 individuals being used in the tests. From the beginning of the 



