40 THE SUGAR-BEET WIREWORM. 



difference in llieii' actions caused by liglil was very noticeable when 

 cages were removed from the insectary and j)hiced in the sunUght. 

 The beetles would fly about at once and before long many pairs 

 could be taken in copulation. When the cages were replaced in the 

 insectary activit}^ would cease as suddenl}- as it had begun. 



ABILITY OF THE ADULTS TO WITHSTAND UNFAVORABLE CONDITIONS. 



The adults showed remarkable ability to withstand shocks of 

 various kinds, whether occasioned by physical injury or by sudden 

 and unfavorable climatic conditions. 



A few cases noted in the field will show their ability to withstand 

 physical injury. When beetles were collected in the helds individuals 

 were noted on several occasions to have been injuretl by their pre- 

 daceous enemies, Calosoma cancellaturn Esch. and C. semilseve Lee, 

 and these were separated from the others so they could be watched. 

 Those which had merely lost some of their legs did not seem to be in 

 the least inconvenienced. Others which were quite severely injured 

 managed to survive as long as most of the other beetles. One, which 

 had its abdomen so nearly severed near the anterior end that it had 

 lost one of its elytra, lived for several days. 



As to their ability to withstand unfavorable weather conditions, 

 it may be stated that while over 25,000 beetles were collected from 

 the field in a period which exceeded a month, very few were found 

 dead. During this period there were sudden and great changes in 

 temperature and several severe rainstorms. 



In view of the fact that the beetles seem to be so hardy in the field, 

 it is difficult to explain the heavy death rate W'liich was noted in all 

 the cages about the time of oviposition. It seems that they must 

 lose much of their vitality during their later life, so that by the time 

 oviposition is about to take place they are comparatively weak. 



METHOD AND TIME OF MATING. 



Wlien once the adults have attamed their normal acti\aty they 

 mate readily during the warmer hours of mild days. Beetles were 

 taken mating as early as March 17, 1912, and as late as A])ril 23, 1912. 

 Every pair taken in copulation in the field was taken between 9.30 

 a. m. and 3 p. m. No pairs were ever found in copulation if there 

 was a strong Annd blowing or if the sky was cloudy or the Aveather 

 cold and rough. The mated pairs were generally found near or 

 beneath the beets under wliich they had been hiding and feeding, 

 though one pair was found in a crack in the soil, about 2 inches below 

 the surface. 



Temperature has a very direct effect on copulation, as was })roved 

 by the laljoratory experiments. Battery-jar cages, when taken from 



