COLONIZATION. . 71 



were freed of the mites by repeatedly scraping them with a small 

 knife and brushing them with a small stiff brush. 



Larvae are more seriously injured by mites, and if attacked to any 

 great extent will die either before or after pupating. This happened 

 in several instances, and shows the necessity of keeping the jars as 

 clean as possible. 



In the spring of 1910 several young Calosoma beetles emerged from 

 hibernation cages but died in a few days. An examination showed 

 that the insides of the bodies were badly decomposed, and a large num- 

 ber of nematode worms was present. These beetles had been reared 

 from larvae late in the summer of 1909, and some of the lot were fed 

 on gipsy moth pupae that had been kept in cold storage and when 

 removed were partially decomposed. 



There was a considerable number of these pupae in the cages late 

 in the summer, and whether the nematode worms are able to feed 

 upon them is not known. The death of the beetles may have been 

 due to entirely different causes, and it is doubtful, judging from our 

 experience, whether these insects are seriously injured by nematodes 

 under field conditions. 



A larva of Carabus monilis Fab. which was attacked, apparently, by 

 the same trouble was sent to the Bureau of Plant Industry for determi- 

 nation, and on careful examination Dr. N. A. Cobb reported that two 

 new species of nematode worms were present, viz, Rhabdites calo- 

 sornitis and R. diplopunctata. He is inclined to believe that these 

 worms were introduced from Europe with the beetles, and that they 

 may be injurious. Inasmuch as the specimen attacked was one that 

 was reared from eggs deposited at the laboratory, the chance of the 

 parasite having been introduced from Europe is somewhat remote. 



COLONIZATION OF CALOSOMA SYCOPHANTA. 



As has been previously stated, the first importations of this beetle 

 that arrived in good condition reached Massachusetts in the spring of 

 1906, and from the number of specimens received it was possible for 

 Mr. Titus and Mr. Mosher to liberate several colonies that spring. The 

 method followed was to put out from 30 to 50 Calosoma beetles in a 

 locality where gipsy moth caterpillars were plentiful, and during the 

 season six colonies were liberated, and 389 beetles were used for this 

 purpose; No attempt was made to determine the sexes of the beetles 

 liberated, and the colonies were placed in the towns of Saugus, Maiden, 

 Winchester, Burlington, and Lynnfield, Mass. 



In the early summer of 1907 the beetle importations were cared for 

 by Mr. Mosher, and one large colony of 331 specimens was liberated 

 early in July in a badly infested woodland directly north of the old 

 parasite laboratory at North Saugus. Later in the season, after the 

 beetle work had been taken up by the writer and Mr. Collins, a few 



