INVESTIGATION OF LIFE HISTOKY. 39 



were eaten than males, and another test was begun by Mr. Collins to 

 determine whether this preference was constant. 



Ten larvae that hatched July 21 were isolated in jars and furnished 

 with 3 male and 3 female gipsy moth pupae, which number was increased 

 as the larvae grew and became more voracious. In this experiment 

 each larva averaged to destroy 12 pupae, 17 per cent of which were 

 males and 83 per cent females. In one case an adult female gipsy 

 moth was eaten by a Calosoma larva when pupae of the gipsy moth 

 of both sexes were present in the jar. 



In order to check this experiment three localities were visited by 

 Mr. J. V. SchafTner, jr., and Mr. H. L. MacKenzie for the purpose of 

 collecting the molted skins of Calosoma larvae and making counts of 

 the number of male and female gipsy moth pupae that had been 

 destroyed. 



The first locality selected, in the Lynn woods, was badly infested 

 with caterpillars earlier in the season, and the larvae of sycopJianta 

 had been found plentiful. All the trees had been banded with 

 tanglefoot, but owing to the fact that a considerable number of eaten 

 pupae, as indicated by the empty pupal shells, was found above the 

 sticky bands, it is probable that the bands had been applied rather 

 late in the season. Trees were also examined in two other localities 

 several miles from the Lynn woods, viz, at Mount Hood, Mass., near 

 the MelrOse and Saugus line, and at Pine Banks Park, Maiden, Mass. 

 In these two localities there was no tanglefoot on the trees. A few 

 of the trees at Pine Banks Park were burlapped and most of them 

 had been sprayed. The trees were climbed and a record kept of all 

 male and female gipsy moth pupae that had been eaten by the 

 Calosoma larvae. The results for 20 trees examined showed that 

 24.5 per cent of the gipsy moth pupae eaten were males and that 

 75.5 per cent were females. These data correspond very closely with 

 those secured under laboratory conditions and indicate that the 

 preference of the larvae for female pupae is pronounced under field 

 conditions. The effect of the preference of the Calosoma larvae for 

 the female pupae of the gipsy moth is thus very apparent and indi- 

 cates that the benefit winch is likely to accrue from this species may 

 be greater than was at first anticipated. 



EXPERIMENT IN FEEDING EARTHWORMS TO LARViE OP CALOSOMA. 



In order to determine whether the larvae of Calosoma sycophanta 

 will feed on other than insect food, 5 newly hatched individuals were 

 supplied with earthworms, as they had proved an acceptable diet for 

 several species of Carabus received from Europe. All the Calosoma 

 larvae died in the first stage, and none of the earthworms was eaten, 

 4 of the larvae lived 4 days, and 1 died at the end of 2 days. This 



