FIGURE II CALOSOMA CALIUUM 

 A beetle which devours the forest cater- 

 pillar o. Larva *. Mature beetle 



The Forest Caterpillar 129 



of insects allied to the flies, and one allied to the bees, wasps, etc. Figure 



12 shows the species that has been most commonly at work in this state, 



though an allied species is also found. These Pimplas are the most efficient 



aids we have in our efforts to destroy 



the forest caterpillar and also the tent 



caterpillar. This parasite lays its egg 



in the cocoons of its host, the intruded 



egg soon hatches and the larva from it 



proceeds to devour the pupa of the 



forest caterpillar. In many parts of 



this state during 1899, a large num- 

 ber of the cocoons were occupied by 



the Pinipla. Lowe' reports that only 



about twelve per cent of the cocoons 



under observation in his laboratory in 



1899 wei-e parasitized. In a lot of 



several hundred which I obtained in 



Addison county, only a third developed moths, the rest being destroyed by 



the Pimplas. In one lot of two hun- 

 dred cocoons hatched in our laboratory 

 but thirty moths came out, the rest 

 being parasitized. This is a most 

 encouraging result, only fifteen per 

 cent of the cocoons reaching the last 

 stage, while eighty-five per cent were 

 destroyed. In this case the parasite 

 was Pimpla conguisitor, figure 12. I 

 have received letters from several 

 parts of the state stating that a large 

 proportion of the cocoons were des- 

 troyed by parasites. Inasmuch as it is 

 the universal rule in such cases that 

 the parasite increases so long as its vic- 

 tims are abundant, we may confidently 

 hope that the coming season will not 

 be as the lasi, but that all over Ver- 

 mont the trees will have a chance to 

 put forth and retain their leaves with 

 much less injury from the caterpillars 

 than for several years past. Such 

 of the lot of cocoons above mentioned 

 as matured produced a far greater 



FIGURB 12 PIMPLA CONQUISITOR 



Male and female, natural size The 

 most useful parasite of the forest cater- 

 pillar From Lowe 



number of males than females. This may have been merely accidental, but 



I Loc. cit., p 41. 



