6 DEPARTMENT BULLETIN 1267, TJ. S. DEPT. OP AGRICULTURE 



leave their eggs. As the beetles themselves require a certain degree 

 of moisture in their surroundings, they avoid very dry situations 

 at all times. Naturally the eggs are most frequently encountered 

 in places to which the beetles resort for the purpose* of feed- 

 ing. For this reason they are most numerous in infested corn- 

 fields, and in old pastures and grassy waste lands which constitute 

 the normal habitat of the species. Field observations indicate that 

 cornfields, especially if they happen to be well drained and are kept 

 in a good state of cultivation, are generally very unfavorable situa- 

 tions for the subsequent development of the larvse; for, although 

 eggs are laid abundantly in com hills, well-grown larvse were rarely 

 found in the same fields later in the season. This may be plausibly 

 accounted for by the fact that the soil in well cultivated cornfields 

 during periods of high temperature and drought is unsuitable for 

 the development of the larvse. 



MANNER OF DEPOSITION 



The process of oviposition has not been observed. In most in- 

 stances it appears that the eggs are deposited singly, although oc- 

 casionally several may be found within a space an inch square. They 

 are rarely inclosed in a clearly defined ball of earth. Possibly this 

 may be due to the rather incoherent nature of the soils in which 

 eggs were obtained in Virginia. At Charlottesville some experi- 

 ments were conducted to ascertain whether the beetles were capable 

 of forming such balls of ear^h by varying the moisture content of 

 the soil and by adding clay to it. As a result a number of more or 

 less firm balls were obtained, each inclosing a cavity containing a 

 single egg (PI. II, B, O, D, E) , but the greater number of eggs were 

 left loose in the soil, apparently with no attempt on the part of the 

 beetles to inclose them in a ball of earth. All the earth balls obtained 

 were found in soil that had been fairly well saturated with water. 

 This circumstance would indicate that the particles of which the 

 earth balls are composed are held together only by the cohesive 

 tenacity of the clay, and not by a glutinous secretion of the beetle. 



NUMBER DEPOSITED 



The number of eggs one female is capable of depositing under 

 natural conditions is difficult to ascertain directly, but some experi- 

 ments conducted at Charlottesville in 1915 provide data which with 

 a certain degree of reservation may be used as the basis for an esti- 

 mate. These data indicate that the average deposition for each indi- 

 vidual may vary from no eggs to rather more than three a day. 

 Part of this variation may be accounted for by fluctuation of tem- 

 perature. It has been repeatedly observed that high temperatures 

 favor deposition, while low temperatures retard it. A part of the 

 variation may also- be attributed to the disturbance incidental to an 

 examination for eggs. 



Usually the average rate of egg production for each individual 

 varies, under particular summer conditions, from 1 egg in every 4 

 days to 2 eggs a day ; and it has been found that a similar range of 

 variation in average daily production occurs if the figures are com- 

 puted on the basis of a longer period, such as a month (or its equiv- 



