August, '19] 



COCKERELL: INSECT PEST SCARCITY 



345 



whole it shows that fumigation and heat sterihzation are safe prac- 

 tices both for grains and legumes at the dosages commonly used and 

 with proper precautions as to the length of exposure and ventilation 

 afterwards. 



Germination Percentage of Beans after Treatment with Excessive Dosage 



1 Temp, readings for series 2 are as follows: 10.45 a. m., 102° F., 1.30, 136° F., 3.45, 154° C. 



ON THE ABSENCE OF INSECT PESTS IN CERTAIN LOCAL- 

 ITIES AND ON CERTAIN PLANTS^ 



By T. D. A. Cockerell, University of Colorado 



The reports of entomologists describe the ravages of insect pests 

 where they occur, but are usually silent concerning the ahsense of 

 infestation. In these days, when we are so greatly concerned to 

 increase the available food-supply, it seems particularly important 

 to ascertain where crops can be grown with the least danger from 

 insect attack. My wife and I, having a "war-garden" in Boulder, 

 Colorado, in 1918, gained some experience which may be worth 

 relating. Our beans {Phaseolus) were completely overrun by Epil- 

 achna corrupta. It was thought that assiduous hand picking early 

 in the season would abate the plague. It doubtless helped, and we 

 got a good many beans; but the beetles came flying to the patch every 



1 This paper should have appeared with those read by title at the Baltimore meet- 

 ing. — Ed. 

 6 



