THE MEXICAN BEAN BEETLE 



13 



oviposition (about 12°) was quite narrow in comparison with the spread 

 of favorable moisture conditions (about 60 per cent). It is apparent that it 

 would require an extremely arid climate to lower the oviposition rates of the 

 beetles sufficiently to reduce the numbers of the pest below that of economic? 

 importance. However, any reduction in oviposition, produced by arid con- 

 ditions, would have an important influence on the total population if the con- 

 ditions were dry enough to seriously affect larval development. 



Summary. A temperature of 37° kUled the adults in a few hours. 



A temperature of 32° with high humidity was very destructive to the adults, 

 but with low humidity was favorable to length of life and egg production. 

 When alternated with lower temperatures the adverse effects were largely 

 overcome below 27°, and partially oft'set at that temperature. 



Figure 1. The Weekly Average Oviposition Rates of Beetles Maintaiued under 

 Controlled Environments. • — Constant Environments ; O — Varied Environments. 



30 



40 



37 



32 



504 



^27Y • 



'ii22 



17 



23 



4 



184 



104 



72 



435 



132 



50 



60 



70 



80 



90 



287 



o oo 



377212 



20 



1S7 2%3 



o 



181 



103 



35 



ZONE W 



ZONE n 



/ 82 299 



250 

 498 



ZONE I 



fl3 



ZONE n 



ZONE m 



266 



om 



467 



192 

 78 



■ 37 



30 



40 



■32 



360 552 



o o 



4 70 457 

 493 123 210 



• • o • 



180 263 



160 ^ 



^42 492 



-27 



430 



f54 S& 



~50 60 70 80 



RELATIVE HUMIDiry-PER CENT 



90 



22 



17 



A temperature of 27° was favorable to length of life of the adults with all 

 humidities used, and to egg production with moist conditions of 60 per cent 

 or above. High moisture environments were more favorable than low humid- 

 ity conditions, but the difference was not so great as with higher tempera- 

 tures. When alternating temperatures were used with 27°, good egg produc- 

 tion resulted with lower temperatures. Humidities of 93 per cent or above 

 may be detrimental to egg production. 



A temperature of 22° with humidities of 40 to 90 per cent was favorable to 

 length of life of the adults and to ^^^ production, although the number of 

 eggs laid was reduced in the dry conditions. High egg yields with alternat- 

 ing temperatures resulted with all conditions above 17°. 



A temperature of 17° was favorable to length of life of the adults but was 



