THE KOUGH-HEADED CORN STALK-BEETLE 7 



alent in days), provided, that no months later than September are 

 taken into consideration. 



From these results it would appear to be a fair inference that on 

 the average each female, under conditions similar to those existing 

 in the experimental cages, is capable of depositing an egg every day 

 during the normal breeding season. If the season lasts between one 

 and two months, a beetle during this period ordinarily may deposit 

 from 30 to 60 eggs. 



GROWTH 



As previously stated, the egg after deposition enlarges until it is 

 nearly or quite double its original size, and simultaneously changes 

 its form until it is almost globular (PL II, B~E). Eggs measured 

 at Charlottesville several days after deposition averaged about 2 

 millimeters in length and 1.5 millimeters in diameter. Unfortu- 

 nately no measurements of freshly laid eggs were made, but the 

 weights of eggs in different stages of growth were determined with 

 the following results: 



In one lot of 15 eggs, all weighed within less than 48 hours after 

 being deposited, a total weight of 0.02013 gram was obtained, an 

 average of 0.001342 gram for each egg. Three days later this same 

 lot weighed 0.04041 gram, an average of 0.002694 for each egg, 

 practically twice the original weight. It was noted that one egg of 

 this lot, on the second weighing, had not increased in size, possibly 

 not having been fertilized, so that the average weight of an egg, 

 at this time, was doubtless somewhat greater than the figures given 

 indicate. 



In a second batch of 15 eggs, weighed when they were between 

 10 and 11 days old, the total weight obtained was 0.05052 gram, 

 an average of 0.003368 gram for each egg, or approximately 2-} 

 times the average of an egg when deposited. 



In a third batch, consisting of 9 eggs estimated as 16 days old 

 and nearly ready to hatch and 6 others which were at least 12 days 

 old, the total weight obtained was 0.06538 gram, an average of 

 0.004359 gram for each egg, or approximately 3^ times the weight 

 of a freshly deposited egg. 



No attempt was made to ascertain the cause of this increase in 

 size and weight of the egg by determining its dry weight, but it is 

 doubtless due to the absorption of water by the egg from the sur- 

 rounding soil. The fact that the dead egg referred to above had not 

 perceptibly increased in bulk after remaining in the soil for three 

 days indicates that only the living eggs are capable of absorbing 

 water. 



MOISTURE REQUIREMENTS 



It appears evident, as intimated in the preceding section, that 

 the presence of a certain amount of available moisture in the soil 

 is an essentia] prerequisite for development. The point was tested 

 experimentally at Charlottesville, and it was learned that the eggs 

 perish if kept in dry soil. 



It is to be regretted that no quantitative determinations of the 

 moisture requirements of (lie eggs were made, as these would have 

 been of value in explaining the conditions under which the species 



