60 



CALOSOMA SYCOPHANTA. 



The data secured from observations made in field colonies indicate 

 that in many of these where beetle larvse were liberated it has been 

 possible to find excellent reproduction the next season. It is prob- 

 able that under natural conditions the average number of eggs laid 

 b}^ all female beetles in the field, regardless of age, will be about 100. 



Young beetles do not lay as many eggs the first season as tliose 

 beetles that are a year older; in fact it appears that a certain propor- 

 tion of the young females does not oviposit at all the first season. 



Table XV gives the results of a series of experiments carried on 

 during the summer of 1910. It shows the difference in the egg-laying 

 habits between the young and the old beetles and indicates the relation 

 between active oviposition and food consumption. 



Table XV. — Difference in the egg-laying_ habits between young and old beetles of Calosoma 

 sycophanta and relation between active oviposition and food consumption, 1910. 



It mil be noted that the old Calosoma beetles ate more gipsy-moth 

 caterpillars and laid many more eggs than the young female beetles, 

 50 per cent of which did not reproduce. The following year these 

 beetles will oviposit freely, as has been repeatedly shown in the 

 previous work. 



In order to ascertain whether any difference would result in breed- 

 ing old males with young females and vice versa, 4 pairs of beetles 

 were tested and the results are given in the following table : 



Table XVI. — Results of breeding Calosoma sycophanta: (1) Old males and young 

 females; and {2) young males and old females. 



1 Eggs laid, but did not hatch. 



The results shown in Table XVI should not be considered as con- 

 clusive owing to the small numbers of beetles used. It has occa- 

 sionally been observed that young females reproduce when placed in 

 jars with old males, and that the old females when kept in captivity 

 witli young males sometimes fail to do so. 



