﻿48 



BULLETIJSr 1374, U. S. DEPARTMENT OF AGRICULTUEE 



Tabi.ic 40. — Thermal death point^ of unprotected pink bollworm larvas exposed in 

 swinging cage in Freas oven 



Number 



Cage 



Time of 



Cage 





of 



temper- 



temper- 



Mortal- 



larvae 



ature 



expos- 



ature 



ity 



exposed 



at start 



1 ure 



at end 







°F. 



Minutes 



°F 



Per cent 



10 



88 



13M 



135 



60 



8 



80 



11}-^ 



135 



62.5 



10 



85 * 



6ii 



135 



50 



10 



77 



15M 



140 



100 



10 



81 



14}^ 



140 



100 



10 



80 



13M 



140 



100 



10 



82 



10 



140 



100 



10 



82 



9M 



140 



100 



10 



83 



9 



140 



100 



10 



84 



8 



140 



100 



5 



81 



7U 



140 



100 



10 



80 



■7H. 



140 



100 



10 



83 



7 



140 



100 



10 



82 



7 



140 



100 



10 



86 



6% 



- 140 



100 



10 



83 



7 



140 



100 



10 



84 



6M 



140 



100 



10 



82 



6H 



141 



100 



8 



82 



19 



145 



100 



10 



92 



lOM 



145 



100 



10 



87 



7K 



145 



100 



10 



85 



m 



145 



100 



10 



84 



6 



145 



100 



10 



79 



18K 



150 



100 



10 



84 



7J^ 



150 



100 



10 



84 



bVi 



150 



100 



Table 41. — Thermal death point of unprotected pink bollworm larvse exposed in 



blotter tray in Freas oven 



Number 

 of larvas 

 exposed 



Tem- 

 perature 

 in tray 

 at start 



Time of 

 exposure 



Tem- 

 perature 

 in tray 

 at end 



Mortality 



i 



° F. 



Minutes 



o p 



Per cent 



8 



81 



WA 



135 



87.5 



1 7 



91 



WA 



135 



100 



i 9 



101 



&}4 



136 



100 



8 



81 



18M 



140 



100 



10 



90 



12M 



140 



100 



7 



100 



nH 



140 



100 



8 



99 



vu 



100 



100 



8 



100 



m 



140 



100 



11 



101 



sy2 



140 



100 



10 



102 



m 



140 



100 1 



8 



102 



m 



140 



100 j 



9 



100 



8 



' 1.40 



100 i 



9 



90 



12J^ 



142 



100 



10 



99 



9H 



142 



100 i 



The air in the oven during all these experiments was dry. The 

 thermal death point as indicated by these tests is 140° F., or between 

 135 and 140° for the conditions under which these tests were made. 

 The results agree closely with those of Willcocks.^^ 



COMMERCIAL DISINFECTING MACHINES 



From the writer's experiments it appeared that the heating of cot- 

 tonseed to a temperature sujfficient to kill the pink boUworms con- 

 tained therein and at the same time not to injure the seed, would 

 be comparatively simple. The main difficulty in perfecting a com- 



n F. G. wmcocks. Op. cit. 



