38 CALOSOMA SYCOPHANTA. 



experiments great difficulty was experienced in securing a sufficient 

 supply of poisoned caterpillars. In areas that were thoroughly 

 sprayed practically all the caterpillars died in a few days, but it 

 was usually possible to find a few caterpillars that were apparently in 

 a perfectly healthy condition. This was undoubtedly due to the fact 

 that they had been feeding on foliage which was not thoroughly 

 sprayed, or from which the poison had been washed by rain. Before 

 the experiments were half completed it was impossible to secure 

 caterpillars that had fed on poisoned foliage; hence, the results given 

 are far from being conclusive. Two of the Calosoma larvae, each of 

 which ate 34 gipsy moth caterpillars, passed through their transforma- 

 tions and developed as perfect beetles, but the others died before 

 reaching the pupal stage. 



Observations in the field would indicate that where areas badly in- 

 fested with the gipsy moth are sprayed, the Calosoma beetles will 

 probably migrate to other sections where caterpillars are abundant. 

 As it is impossible for the larvae of the Calosoma to migrate, it is prob- 

 able that if a large number of eggs was laid by the beetles a con- 

 siderable proportion of the larvae resulting would die from starva- 

 tion on account of the Jack of a sufficient number of caterpillars to 

 furnish ample food supply. Undoubtedly some of the larvae would 

 be able to obtain sufficient food to pass through their transformations; 

 hence there is relatively little chance of completely destroying this 

 species as a result of arsenical spraying. 



It is evident, however, in making liberations of Calosoma beetles 

 in the field, that this should be done in localities where spraying will 

 not be attempted, in order that the insects may have every oppor- 

 tunity to develop and increase. This policy has been followed, and 

 in only a few cases has the spraying of the territory where the beetles 

 were liberated been permitted, and then only when it became appar- 

 ent that serious defoliation would result unless the work was done. 

 It is evident that as soon as the species becomes firmly established and 

 dispersed over a large area, as is now the case in a portion of the 

 infested district, spraying will have little effect on the number of 

 specimens which will develop. 



EXPERIMENTS IN FEEDING GIPSY MOTH PUP.E TO CALOSOMA LARV.E. 



The larvae of Calosoma sycophanta are very fond of gipsy moth 

 pupae and destroy large numbers of them in the field. In order to 

 determine how many are eaten, a series of experiments was begun 

 with 10 Calosoma larvae that hatched July 11, 1910. They were 

 fed separately upon gipsy moth pupae until they were fully devel- 

 oped and descended into the ground to pupate. The average num- 

 ber of pupae which each beetle larva consumed was 13. In the 

 course of this experiment it appeared that more female pupae 



