38 THE SUGAR-BEET WIREWORM. 



soil was kept quite damp by additions of water from time to time. 

 This cage presented very much the condition which would hold 

 in the field if all the food could be eliminated. Five hundred 

 and sixty beetles were used in this experiment, with the following 

 results : 



About 60 died before 10 days. 

 About 100 died before 10-15 days. 

 About 200 died before 15-18 days. 

 About ] 00 died before 18-22 days. 

 About 60 died before 22-25 days. 

 About ao died before 25-28 days. 

 About 6 died before 28-30 days. 

 About 2 died before 30-31 days. 

 About 1 lived for 34 days. 

 One lived for 40 days. 



The last 10 to die were females. Their abdomens were quite 

 swollen, but they did not lay any eggs — at least none could be 

 found — and when they were dissected after death the ovaries, while 

 containing some eggs almost mature, were quite shrunken and dry. 

 None of the beetles was very active after 15 (hiys, and after 25 days 

 they were very feeble, the last few to die being unable to walk during 

 the last days they lived. 



Many adults were separated and kept in vials and given food but 

 no water. Care was exercised to have this food as dry as possible. 

 Out of 78 used in this experiment only 12 died during the first 15 

 days, and the remainder were quite active. It was so difficult to 

 obtain the food dry enough to affect them that the experiment was 

 discontinued. 



LENGTH OF TIME ADULTS CAN BE SUBMERGED. 



Several adults were submerged in water in a tube and kept below 

 the surface by a smaller tube placed within the first one. The 

 water was j)crfectly clear and care was taken to remove all the air. 

 At the end of 15 minutes the beetles had ceased to move and at the 

 end of 20 minutes they were removed. They seemed dead, but within 

 a few minutes were moving about actively and seemed none the worse 

 for their treatment. 



Another lot was submerged for 40 minutes and within a half hour 

 after being taken out were as active as ever. The tests were not 

 carried further, as tliese were considered as severe as any they would 

 be subjected to uncU^r field conditions. Twenty adults were floated 

 on water for 15 iiours and at the end of that time only three were 

 dead. From tliese results it was concluded that a majority of the 

 beetles could survive a severe storm. 



