L INSECT ECOLOGY 353 



range is different for different species, for the same species in differ- 

 em seasons or places, and is different even for different individuals of 

 the same species under apparently equal conditions, and for different 

 stages in the growth or development of the same individual. The 

 temperature-range is affected by food, moisture, evaporation, and 

 several other factors. 



Growth and development proceed most rapidly in a certain optimum 

 range of temperature, within which there is, at least theoretically, an 

 optimum degree of temperature. At and above a certain degree of 

 high temperature heat-rigor sets in, and may or may not be fatal to an 

 organism, according to the duration of the exposure to the temperature. 

 This maximum temperature has as its upper limit the ultramaximum, 

 at which the organism dies at once, probably because of the coagulation 

 of proteids in the protoplasm. At a certain degree of low temperature, 

 cold-rigor takes place; the point at which it occurs being near the freez- 

 ing point, on account of the fluid content of protoplasm. Below this 

 minimum is an ultraminimum temperature, at which the organism dies. 



The following examples of temperature-limits are from Davenport's 

 Experimental Morphology. 



INSECT MAXIMUM ULTRAMAXIMUM 



Springtail, Podura similata 27 C. 36 .0 C. 



Mosquito, Culex pipiens 40 C. 



Larva of fly, Musca vomitoria 42 . 5 C. 



Pupa of fly, Musca vomitoria 43 . 7 C. 



Silkworm, Bombyx mori 42 . 5 C. 



Back-swimmer, Notonecta 45 . o C. 



It should be noted that the Podura (near Achorutes) has a thin 

 integument, and can not live in a dry atmosphere. The pupa of the 

 fly is protected somewhat by its puparium, and the back-swimmer by 

 a fairly thick integument. 



INSECT ULTRAMINIMUM 



Honey bee, Apis mellifera i . 5 C. 



House fly, Musca domestica 5 . o C. 



Larva of cockchafer, Melolontha ; 15 . o C. 



Adult cockchafer, Melolontha 18 . o C. 



Davenport notes that the large size and thick covering of the beetle, 

 Melolontha prevent the rapid loss of heat. 



Activity in Relation to Temperature. The range of activity of the 

 adult cotton boll weevil lies between 56 F. and 95 F. From 95 to 

 122 is the range of aestivation, within which the beetles are inactive. 

 From 122 to 140 (soil temperature) is an upper range of fatal tem- 



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