Séance du 16 Avril I92â 
149 
On predicting the Development Cycles 
of insects 
9, Ceratitis capitata Wied. 
by Dr. F. S. Bodenheimer, 
Entomologist, P. Z. E. Agr. Exp. Sial. 
Tel-Aviv — Palestine 
Till to some years ago the duration of develop¬ 
ment of an insect was usually considered in direct 
relations to the surrounding temperature only. W.D. 
Pierce has worked out in his fundamental papers the 
relation to the combination of surrounding tempera¬ 
ture and air humidity. For a few of the most impor¬ 
tant insects in medical Entomology, the experimental 
data have been determined and it is sufficient to-day 
to have the data about temperature and air humidity 
of a country, in order to be able to infer at once im¬ 
portant information on development optimum and 
minimum, and on the mortality of these insects in 
the different seasons. But in Agricultural Entomology 
nothing has been done in this direction up to date. 
We must content ourselves with estimations only 
based on the temperature, till the more important 
Pierce-data are fixed by some of the great Entomolo¬ 
gical institutions. 
The Development-Temperature Rule, that the 
product of temperature in °G (v) and development 
time in days (t) is constant was evidently wrong. But 
recently it has been corrected by Blunck and it seems, 
that in Blunck’s new formula we are in the possession 
of an useful basis for such estimations. 
