No. 430.] THE DIFFUSION OF INSECTS. 801 
thunderstorm acting separately would not bring about such a 
condition of affairs. 
I have stated that, in applying trap lights or lanterns, or edible 
baits like sweetened sour beer, we, as a rule, secure males 
and spent females, but the influence of weather conditions that 
usually precede a thunderstorm (that is, a close, sultry con- 
dition) has the effect of bringing out both sexes, — a result 
due, so far as can now be determined, to some subtile action 
on their sexual life. As Professor Sajó so aptly illustrates 
this point, I will quote him again quite fully. ** What influence 
the weather has, especially on the activity of sexual life, must 
be known to every zoólogist; even man is not an exception 
from these ‘living barometers.’ Not only children, not only 
the female sex, but the sick ones experience the influence of 
the weather on the functions, especially on the nervous system ; 
and everybody without exception are thus influenced, though 
not all may be aware of the fact. The same causes that in 
many produce unrest and irritation render others dizzy, 
stupid, or sleepy, according to the temperament of the indi- 
vidual.” The effect of electricity on the nervous systems of 
insects, especially as relative to their love affairs, would con- 
stitute an interesting study, and one that ought to be carried 
out; but even as it is, we can see that the thunderstorm, in 
conjunction with the wind, may accomplish in the diffusion of 
insects that which neither element alone would bring about. 
