258 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



crops. He reports that his corn was not noticeably injured, although 

 a few grubs were present in the soil, while many of his neighbors' 

 corn-fields were severely damaged. The only loss which he noted 

 was on a far side of the farm where potatoes were injured somewhat. 

 Too much emphasis must not be laid on this fairly accurate observa- 

 tion, because the grubs were destroyed in considerable numbers by 

 diseases, aided by the damp weather. Had this summer been a 

 normal season, we feel that a fair estimate of value of the experiments 

 could have been made. 



At Lancaster, where fifteen light traps were running, it is estimated 

 that under ordinary farm conditions where help is comparatively 

 cheap, the total cost of operation of the lights, exclusive of the initial 

 expense of lights and pans, would not exceed twenty-five or thirty 

 cents a day for the entire period. It is further evident with the 

 knowledge that we have of the small flights of beetles in temperatures 

 under 66° F., the cost of operation could be materially reduced by 

 omitting the lights on nights of low temperature. 



The Proportion of Sexes 



Altogether our records show that the numbers of males caught 

 greatly exceed the females, it is possible that some other reason 

 may be attributed to this fact rather than the smaller degree of 

 attractiveness to lights in the females. It may be possible that 

 normally there are larger numbers of males than females. 



It may be argued that the catch of such a small proportion of 

 females would militate against the success of light traps in economic 

 control, but again, if the beetles are polyandrous, as has been suggested 

 by some entomologists, there may be an unexpected advantage in 

 catching such a large number of the males. 



Our records further show that with the more common species the 

 females form a larger percentage of the catch in the earlier part of 

 the season. 



On the whole, this question of possible control of the white grub 

 pest by trapping of the adult beetles must receive much further 

 attention and consideration before any definite recommendations can 

 be made. 



Biological Experiments 



The following experiments were undertaken in order to learn as 

 much of the normal life of white grubs as possible. No investigations 

 seem to have been made heretofore on the activities of any under- 

 ground animals in their natural environment. For this reason the 

 only control measures which have been suggested in the past are 



