No. 376.] MWOTES ON THERMOMETER CRICKETS. 263 
FURTHER NOTES ON THERMOMETER CRICKETS. 
CARL A. BESSEY anp EDWARD A. BESSEY. 
THE article on “The Cricket as a Thermometer” by Professor 
Dolbear in the November Naturalist reminds us of a series of some- 
what similar observations upon the chirping of the tree cricket 
(Zcanthus niveus) which we made in Lincoln, Nebr., during August 
and part of September of the past summer. 
Noticing that the rate of chirping was approximately the same in 
different parts of the city for any particular time, but that this rate 
varied in a marked degree from day to day, we were led to make an 
investigation of the conditions accompanying these variations. We 
began taking observations upon this rate along with thermometer 
readings on August 13. 
Finding that each cricket remained in the same tree for days at a 
time and that in different trees the rate was often slightly different, 
we thought best to take a series of observations on certain individual 
insects. These were designated for convenience as A, B, C, etc. For 
example, we found that at a temperature of 66.5° F., B chirped 122, 
E 121, F 122, and G 118 times per minute. Through a quite wide 
temperature range G almost invariably chirped at a lower rate than 
either E or F 
Observations were made on the rate of chirping of eight different 
crickets for periods ranging from a few days to about three weeks. 
Some could be distinguished for only a few days, while others, 
notably E and F, chirped very regularly every evening for three 
weeks or more. On evenings when the temperature was falling 
rapidly, observations were made several times, with results very 
markedly showing the effect of temperature change. For A five 
different observations were made, for B nine, C four, D one, E thirty, 
F twenty-two, G ten, and H five. 
One cool evening a cricket was caught and brought into a warm 
room. Ina few minutes it began to chirp nearly twice as rapidly as 
the out-of-door crickets. Its rate very nearly conformed to the 
observed rate maintained other evenings out of doors under the same 
temperature conditions. 
From this series of observations we found that the rate of chirping 
was, as Professor Dolbear says, very closely dependent on the 
temperature. 
