INVESTIGATION OF LIFE HISTORY. 25 



eggs, as is indicated a few days later by the hatching record. This 

 held true until the food supply began to fail late in July. 



It will also be noted that the greatest mortality of females occurred 

 about the last of July and indicates the relation between tempera- 

 ture, egg laying, food supply, and mortality. 



Notes on Hatching. 



As the eggs are deposited in the earth by the female Calosoma 

 beetles, it is difficult to secure exact data on the superficial changes 

 that take place. The following note is of interest. 



On August 2, 1907, two eggs laid that day were placed in earth 

 in a jar, to observe the changes that take place previous to hatching. 

 They were placed 1 inch below the surface of the earth and against 

 the side of the glass, so that they could be easily seen. August 6, 

 they were somewhat darker in color and had become slightly kidney- 

 shaped. At 8 a. m., August 7, a larva had hatched from one egg 

 and the other was dark gray in color, the segmentation of the body 

 being plainly visible. At 2 p. m. the egg had hatched and the larva 

 had moved away from the cavity. At 8 a. m., August 8, the larva 

 which hatched first had made a tunnel to the surface of the 

 ground, but had returned and was occupying the egg cavity. The 

 other larva was not in sight. At 2 p. m. both larvae were crawling 

 on the earth in the jar in search of food. 



Usually the eggs do not begin to assume a darker color until 

 about 24 hours before hatching, although the change in outline and 

 indications of segmentation are apparent before that time. 



Infertile eggs sometimes become kidney-shaped, but usually the 

 outline is more or less irregular and segmentation of the contents 

 has never been observed. Such eggs usually contract to some 

 extent in a few days. In most cases they become dark in color and 

 gradually shrivel up and disappear in the earth. 



To illustrate the care which must be taken in transferring the eggs 

 of this insect, if it is necessary to do so, the following case is cited. 



On July 23, 1908, a Riley cage, having a galvanized iron base con- 

 taining earth, was examined for eggs. It contained a supply of 

 Calosoma beetles which had been received from Europe some time 

 previous. The insects were transferred to another cage and the 

 earth was found to contain 253 eggs, which were placed in jars to 

 observe hatching. One hundred and eighty-five larvae developed 

 from these eggs, or 73 per cent of the total number. Probably some 

 of them were infertile, but allowing that this was the case, at least 

 20 per cent of the eggs must have been injured during the transfer. 



