COLONIZATION. 73 



liberated at the same time, and in this ease the number of larvae lib- 

 erated is often reduced one-half. 



The method of liberating field colonies of Calosoma beetles has de- 

 pended on whether adults or larvae were to be planted. When adults 

 were used, they were taken to the area selected and scattered about 

 among the badly infested trees. 



More care was required in distributing larval colonies as it was neces- 

 sary to pack the larvae separately so that they would not injure each 

 other before they were turned loose. 



In 1909 the larva? were placed separately in glass tubes, both ends 

 of which were plugged with cotton. Before inserting the last plug, a 



Fig. 21.— Two hundred tubes, each containing a larva of Calosoma sycophanta, ready for coloniza- 

 tion. (Original.) 



small amount of earth and sometimes a caterpillar or pupa was added 

 with the beetle larva. These tubes were packed in a basket and taken 

 to the place where the colony was to be liberated. (See fig. 21.) On 

 arrival the contents were dumped at the base of infested trees and the 

 tubes returned for refilling. Frequently the tubes became broken in 

 handling and transit, and occasionally some of the larvae made their 

 way through the cotton plugs and escaped. 



In 1910, a better device was used (fig. 22), which consisted of sev- 

 eral units of wood in which was bored a double row of 10 holes, so that 

 each block would accommodate 20 larvae. The bottom of the block 



