INVESTIGATION OF LIFE HISTORY. 



23 



One female beetle received from Europe in July, 1907, was kept 

 under observation at the laboratory for two years, so that the length 

 of life may normally be considerably longer. 



Nearly one-half of the beetles reared from eggs in 1907 that emerged 

 from the earth in the spring of 1908 survived the summers of 1908 and 

 1909, and went into hibernation in the fall. This serves to illustrate 

 the prolonged period throughout which accurate records must be 

 kept, and the care with which the work must be conducted in order to 

 secure correct data. 



During the summer of 1910 measurements were made of 12 freshly- 

 laid eggs and the same number of larvae on entering each stage, and 

 these notes are included in the descriptions of stages which follow. 



THE EGG. 



Twelve fresh eggs gave the following average measurements: 

 Length, 5.2 mm., width, 2.4 mm. They are somewhat elliptical in 

 form, with a slight taper toward one end. The color is white, with 

 a faint yellowish tinge. They vary somewhat in size and form and 

 before hatching often become somewhat kidney-shaped. 



The time spent in the egg stage is from 3 to 10 days, and depends 

 largely on the temperature. Careful observations on 2,000 eggs that 

 were laid from May 15 to August 18, 1908, are summarized as follows: 





Table III. — Duration of the egg stage in 



Calosoma sycoph 



anta. 







Egg stage. 



Number of eggs in— 





May. 



June. 



July. 



August. 



Total. 



3 days 







75 

 444 

 451 



36 



13 



7 

 3 

 3 



88 



4 days 





78 

 605 

 164 



32 

 8 



529 







1,059 



6 days 



23 



39 



9 



6 



1 



226 



7 days 





71 



8 days 







17 



9 days 







6 



10 days 



3 







4 











Average time in egg stage: Days. 



May 7 



June 5.2 



July 4. 4 



August 4 



The eggs recorded as hatching in May were secured from females 

 that were taken from hibernation in March, April, and May and fed 

 in the laboratory. Oviposition seldom takes place under natural 

 conditions in the month of May. 



The average length of time spent in the egg stage, based on the 

 hatching each month during the summer, was : May, 7 days ; June, 

 5.2 days; July, 4.4 days; and August, 4 days. 



The table also shows that 4.4 per cent of the eggs laid in 1908 

 hatched in 3 days, 26.4 per cent in 4, 53 per cent in 5, 11.3 per cent 



