Apr. 28,1923 
Studies on the Temperature of Individual Insects 
277 
Dutrochet (7) used a thermocouple made by soldering an iron and 
copper wire together. He placed one couple in the body of the insect 
and the. other couple in the body of a dead insect of the same species 
or in paper. He fastened several bees to a hive by means of a ^read 
and took temperature readings while the bees were very active. One 
couple was placed 5 mm. deep in the body of the bee; the other couple 
was wrapped in paper to protect it from radiation. The air tempera¬ 
ture was constant for four hours (i9.2°C.). This experiment showed that 
the temperature of the insect waso.i8°C. lower than that of the surround¬ 
ing air. The bees were next placed in a bell jar with the air dampened. 
They then had a temperature of o.i8°C. higher than the air temperature. 
Experiments with Bomhus hortorum were also performed. The thermo¬ 
couple was not placed in the body but merely placed against it. The 
bee was then wrapped up in a piece of gauze which caused it to become 
very much excited. Under these conditions the temperature was 0.5‘^C. 
higher than that of the surrounding air. As the bee became quiet, its 
temperature was o.03°C. lower than the air temperature. Dutrochet 
concluded that insects when active had a temperature higher than the 
surrounding air, when inactive a temperature that corresponded to that 
of the surrounding air. 
Dzierzon (8) observed that bees became motionless at 5°R. (6.25°C.). 
Donhoff (5) placed 200 bees in a glass container the temperature of 
which was 22.5'^C. In a short time the temperature had risen to 34.4°C. 
He also pressed an individual bee against a bbermometer and found it to 
have a temperature of i5/i6°C. higher than the air. He concluded that 
the difference in temperature between the bee and the surrounding air 
was greater when the air temperature was low and less when the air 
temperature was high. 
Schonfeld (17) placed 100 bees in a water glass which was perfectly dry. 
A piece of old dried wax was attached to the cover of the glass in which 
there was a hole for the insertion of the thermometer. A small board 
was placed in the bottom of the glass on which the thermometer rested. 
The entire apparatus was placed on a cook stove. After 3 hours and 
25 minutes the thermometer had risen from lo'^R. (i8.75°C.) to 3i.5^R. 
(39.3^0.). All the bees, with the exception of 5, were found standing 
on the wax. One bee began to fan as the temperature reached 32.7°R. 
(40.8^0.) and at 36®R. (45.o°C.) 80 bees fell to the bottom of the glass 
and died. Sixteen bees were still living at 46°R. (57-5*^^.), and when 
the cover was removed they flew out. The experiment was repeated 
and 2 bees withstood the temperature of 48.2°R. (6o.2®C.) and flew 
away when the glass was opened. 
Girard (9) carried on several experiments on insect temperature and 
found that the bumblebee had a lower temperature when in lack of 
honey. He concluded also that Hymenoptera had a higher temperature 
than the surrounding air but a significantly lower temperature than the 
Lepidoptera and Diptera. 
Donhoff (6) observed that bees soon died at when placed in 
frozen grotmd. 
Molin (12) found that bees became motionless at 5°R. (6.25°C.) and 
that at 7®R. (8.75°C.) they cleaned themselves and carried water. They 
left the hive and flew into the field at i2°R. (i5°C.). 
Koschewnifew (ii) noted that bees kept at a temperature between 0° 
and i°R. (0° to 1.25^0.) for loK hours lived. Other bees that were 
motionless for 30 horns at a temperature of — i°R. (--i.25°C.) also 
