THE CALOSOMA BEETLE IN NEW ENGLAND, 9 



The larvae usually cut a hole between the segments of the pupae 

 (PL V), and after feeding begins the hole is gradually enlarged 

 until the front portion of the body finds entrance to the pupa. The 

 internal contents in most cases is completely devoured before the 

 larva leaves the pupa to search for other food. The holes are always 

 irregular in outline and can be easily distinguished from the exit 

 holes of parasites. Gipsy-moth pupa? massed on the trunks of trees, 

 underneath branches, or below burlap bands (PL VI) are favored 

 locations as feeding grounds for Calosoma larvae. In many towns 

 in the infested gipsy-moth district one or more Calosoma larvae can 

 usually be found in each mass of gipsy-moth pupae examined. These 

 predaceous larvae occasionally attack female moths, and several cases 

 have been noted where the latter have been killed before they had an 

 opportunity to deposit eggs. 



Sycophanta larvae feed freely on any lepidopterous larvae or pupae 

 which they may find. A considerable number of cases have been 

 noted where the larvae have cut through the cocoons of the American 

 tent caterpillar (Malacosoma americana Fab.) and forest tent cater- 

 pillar (Malacosoma disstria Hiibw.) and have destroyed the pupa^ 

 within. 



The life history of the Calosoma beetle is well adapted to that of 

 the gipsy moth. The beetles are present and active during the time 

 of year when gipsy-moth caterpillars are abundant and the larvae are 

 active and feeding while the gipsy moth is still in the pupal stage. 

 No other common lepidopterous species which occurs in New Eng- 

 land is so well adapted as a host of this beetle as the gipsy moth, 

 and although large numbers of other caterpillars and pupae are de- 

 stroyed annually, the increase of the beetle is not as satisfactory in 

 regions where the gipsy moth is not available for food. 



In the summer of 1908 several series of experiments were con- 

 ducted to determine the number of sixth-stage gipsy-moth cater- 

 pillars destroyed by the larvae of G. sycophanta. It was found that 

 on the average a single larva of this beetle would kill 41 full-grown 

 caterpillars between the time of hatching and pupation. If smaller 

 larvae were attacked, a greater number would, of course, be destroyed. 

 It is safe to say that 50 or more caterpillars would be necessary to 

 satisfy the appetite of a Calosoma larva under field conditions. Most 

 of the sycophanta larvae hatch at a time when more gipsy-moth pupae 

 than caterpillars are available for food. Experiments show that on 

 the average about 13 female pupae are destroyed by each larva when 

 fed in captivity. Observations in the field and jar experiments both 

 indicate that a greater percentage of females than males is destroyed 

 by the Calosoma larvae, the average ratio being 75 per cent females 

 to 50 per cent males. 



93012°— Bull. 251—15 2 



