LIFE HISTORY AND HABITS. 37 



tended to become foul. The two types last mentioned were about 

 equal in efFiciency, but the main difficulty lay in the fact that they 

 were small and it was easy to overcrowd them. 



The cage used most successfully was a large screen cage of the 

 common type, kept outdoors. (See fig. 8.) Within the cage were 

 several flowerpots, buried to the level of the ground, each containing 

 young bept plants. The soil in the pots was kept loose and damp, 

 and the soil around the flowerpots was tamped hard. This cage was 

 large, well ventilated, and gave the beetles plenty of room in which 

 to fly about. Its best feature lay in the fact that the beetles all de- 

 posited their eggs in the flowerpots, since this was the only place 

 where they could ])ury themselves easily. It this way the eggs were 

 concentrated much more than they would have been under natural 

 circumstances. As soon as one flowerpot contained a great many 

 eggs it could be removed and another substituted. This cage also 

 gave natural conditions, as the soil it contained was just as damp as 

 that in the field, and since the cage was placed in the sun and was so 

 airy the beetles were always kept at the field temperature. The 

 death rate was very much lower in this cage than in any of the others 

 and there were five adults in it for some time after all had disappeared 

 in the other cages. 



DURATION OF LIFE UNDER VARYING CONDITIONS. 



To test the duration of life under var3dng conditions some adults 

 were placed in various styles of cages and others were kept under 

 vai'ious conditions as concerned the food and water supply. Some 

 were kept without either food or water, some with food but without 

 water, and some with water but without food. In every instance 

 the beetles lived much longer than was expected of them and proved 

 that they are not only quite hardy but can get along on little food. 



One hundred and forty adults were placed in dry battery jars 

 without food or water, and the jars were closed with gauze. The 

 results w^ere as follows: 



Eighty-two adults died in from 9 to 12 days. 

 Forty adults died in from 12 to 14 days. 

 Eleven adults died in from 14 to 16 days. 

 Five adults died in from 16 to 18 days. 

 One adult lived 20 days. 

 One adult lived 22 days. 



None of the beetles was very active after the twelfth day. These 

 conditions were much more severe than any that they might encoun- 

 ter under field conditions. 



The adults kept with water but without food were also kept in 

 battery jars. These jars contained about 3 inches of soil, and this 



