EXPERIMENTS AGAINST CARPET BEETLES. 35 



Table IX. — Effect of heat on carpet-heetle larvae. 



Length of 



Degree of 





exposure. 



heat. 





Minutes. 



'F. 



Per cent killed. 



10 



128 



100 



15 



125 



100 



30 



120 



100 



10 



120 



30 



30 



110 







10 



110 







30 



105 







Effect on eggs. — ^Ten or more eggs on a piece of flannel were placed 

 in an incubator for varying lengths of time. The results are shown 

 in Table X. 



Table X. — Effect of heat on carpet-beetle eggs. 



Length of 



Degree of 





exposure. 



heat. 





Minutes. 



°F. 



Per cent killed. 



11 



130 



100 



11 



128 



50 



19 



125 



100 



16 



125 



100 



31 



120 







11 



120 







31 



110 







11 



110 







31 



105 







To kill all larvae, a temperature of 120° F. maintained for 30 

 minutes was required. Higher temperatures for less time were 

 equally efficient. To prevent all eggs from hatching, it would ap- 

 pear, from these limited tests, that the length of exposure is more 

 important than the temperature. A temperature of 125° F. for 

 16 minutes killed the eggs, while an exposure of 128° F. for 11 

 minutes failed to kill all the eggs. 



Two pieces of flannel, each containing 10 or more eggs, were placed 

 in the hot sun for three hours. The temperature on the flannel 

 ranged from 109° F. to 120° F. Observations showed that none of 

 the eggs so exposed hatched, while practically all the eggs on the un- 

 exposed flannel hatched. 



HOT WATER. 



Effect on carfet-'heetle larvce and eggs. — Flannel dipped for five 

 seconds in water at a temperature of 140° F. resulted in the killing 

 of both larva3 and eggs, while water at a temperature of 122° F. failed 

 to kill either larvae or eggs. 



