1914] Longevity of Insects 331 
Chart I records the results of these two experiments. The 
abscissa of each of the points marked with circles is the longevity 
of the larve at the constant temperature represented by the 
ordinate. Each arrow leaving one of these points runs to a 
point indicating in the same manner the longevity resulting 
from the treatment at the two temperatures. 
Chart I shows that from any change in temperature there 
results an increased longevity of the larve, as follows: 








Two Days . Longevit 
Treatment at | Followed by Results in at acnetane 
98° F. 58> BE. Same longevity as.............. OSnHe 
98° F. 68° F. Increased longevity over....... 68° F. 
68° F. 98° F. Decreased longevity below..... 98° F. 
68° F. 58° F. Decreased longevity below..... 58° F. 
58~ EF. 98° F. Increased longevity over....... 98° F. 
58° F. 68° F. Increased longevity over....... 68° F. 
82° F. 64° F. Increased longevity over....... 64° F. 
64° F. 82° F. Decreased longevity below..... 82° F. 
64° F. 46° F, Increased longevity over....... 46° F. 
46° F. 82° F. Increased longevity over....... 82° F. 
46° F. 64° F. Increased longevity over....... 64° F. 


The exceptions to this rule are in three cases: (a) where 68° 
F. is the preliminary two day treatment, there is a decrease, 
(b) where the change is from 98°F. to 58°F. there is no increase 
and (c) where 64°F. is followed by 82°F. there is a decrease in 
the longevity. 
From the data recorded on Chart I, we may form two con- 
clusions; (1) that the life of the larve of Phryganidia californica 
will be lengthened at any temperature (when starvation is a 
factor) by placing the insect for two days at either a high or a 
low temperature; (2) that the life of the larvae of Phryganidia 
californica will be shortened at any temperature (when starva- 
tion is a factor) by placing the insect for two day at a medium 
temperature. 
The temperatures that have been found to have the char- 
acteristic effects described are: ‘‘High’’ 98-82°F. 
Above 98°F. will probably have other characteristics as 98° 
F. already shows a transition in that it does not cause an in- 
crease in longevity when followed by a low temperature. 
““Medium”’ 68-64°F. 
