April, '19] McCOLLOCH: ELEODES OPACA 189 



June. From this time on until the middle of October the adults are 

 to be found in the field, the greatest number being present during July 

 and early August. The normal length of life for the adult is from two 

 to four months. Most of the beetles under observation lived from 60 

 to 90 days, while one male lived 130 days. Unlike Eleodes tricostata 

 none of the beetles of this species hibernate over winter, and thus far 

 the writer has never found adults later than October 18. While most 

 of the adults emerged during June in the life-history studies, no mating 

 was observed previous to July 3. During the four years that these 

 studies have been under way, copulation has occurred the first week in 

 July, and oviposition usually follows in two or three days. The first 

 oviposition was noted July 5, and the last on October 4. The period 

 of oviposition, together with the number of eggs per female was deter- 

 mined for seven mated females in 1915, this data being summarized in 

 the accompanying table. Similar studies made the following years 

 gave essentially the same results. 



Oviposition Record for Seven Females, 1915 



Average 30 233 181.1 5.3 7.2 19.8 



While matings were observed frequently in all cages, the presence of 

 the male was not necessary after fertilization once took place. In the 

 case of female No. 1, the male died July 18, but she continued to de- 

 posit fertile eggs until September 6. The proportion of sexes as deter- 

 mined from reared and collected adults indicate that the females are 

 shghtly in excess of the males. Fifty-six per cent of the beetles taken 

 in the field have been females, while 54 per cent of the reared beetles 

 were females. 



The adults of Eleodes opoca, like many of the other members of the 

 genus Eleodes, are more or less nocturnal or crepuscular in their habits. 

 In the field they are generally most active early in the morning, and 

 about dusk in the evening, while during the hotter parts of the day they 

 are to be found hiding under any suitable covering. In the prairie lands, 

 rocks, manure, piles of weeds, and clumps of grass off"cr ideal hiding 

 places, while in the wheat fields they are to be found under sliocks and 

 around stacks of wheat, under Russian thistles, in clumps of volunteer 



