6 BULLETIN 417^ V. S. DEPARTMENT OP AGRICULTURE. 



NUMBER OF GENERATIONS OF CALOSOMA. 



Strictly speaking, all the species of this genus thus far reared and 

 studied have only one generation annually. A slight deviation from 

 this rule was noted in the case of 2 males and 4 females of C. scrutator 

 Fab. that were received from Onset, Mass., August 3, 1909. These 

 beetles were placed in a Riley cage and given plenty of food at fre- 

 quent intervals. On September 23 and 27, 23 small larvae hatched from 

 eggs deposited by one or more of the females. They were isolated 

 and later fed inside the laboratory. Adults developed from some of 

 these larvae, November 9 to 12, and a few days later (November 16 

 and 19) were found on the earth in the jar searching for food. They 

 fed until December 16, before entering hibernation. 



This instance is cited to show that reproduction may take place in 

 some cases very late in the season. Other females of the same species, 

 confined at the laboratory that year, began ovipositing as early as 

 June 14, which gave ample time for adults to develop before the 

 middle of August. It is doubtful whether the adults of O. scrutator 

 under field conditions in New England come to the surface of the 

 earth for food as soon as they issue. The instance just cited indicates 

 that they may do this in the southern United States. 



FOOD HABITS OF ADULTS AND LARV^ OF CALOSOMA. 



The kind of food consumed by the adults and larvae of the various 

 Bpecies varies greatly under natural conditions. Of all the species 

 with which experiments were made at the laboratory, everything 

 offered in the way of lepidopterous larvae and pupae was eaten, and 

 in some cases immature stages of Coleoptera and Diptera were 

 attacked sparingly. 



The caterpillars of Portlietria dispar L. and Malacosoma americana 

 Fab. were fed more than other species because of their abundance in 

 the field at the time needed (PI. II, A). Caterpillars of Ewproctis 

 cJirysorrhoea were abundant enough, even more so in some localities 

 than the former species, but the ubiquitous and poisonous hairs of 

 the caterpillars of the latter made their general use impracticable. 



The beetles are ravenous for food at the time when the caterpillars 

 of the foregoing species are in season and their larvae feed voraciously 

 upon either caterpillars or pupae but usually destroy more of the 

 latter. This is particularly true of the larvae of Calosoma sycophanta 

 in connection with Portlietria dispar. Many field observations have 

 shown that the larvae of the beetles are abundant at the precise time 

 when caterpillars of this species are entering the pupal stage, and as 

 much food is required for their development they are particularly 

 adapted for destroyers of this pest. The same is true with the 

 larvae of C frigidum in their feeding upon larvae and pupae of 

 Heterocampa guttivitta Walk, These observations were published by 

 Mr. W. F. Fiske ^ and the senior writer in 1910. On July 31 of that 

 5^ear Messrs. Fiske and Burgess found the adults of the beetle 

 climbing trees and preying upon the caterpillars of the moth in Tam- 

 worth, N. H, On the same date 12 of the beetle larvae were found 



i.Fiske, W. F., and Burgess, A. F. The natural control of Heterocampa guttivitta. In Jour. Econ. 

 Ent., V. 3, no. 5, p. 389-394, 1910. 



Burgess, A. F. Notes on Calosoma frigidum Kirby, a native beneficial insect. In Jour. Econ. Ent, 

 V. 3, no. 2, p. 217-222, 1910. 



