July 15,1925 Effect of Low Temperatures on Bruchus obtedus 
169 
Table I. — Data on freezing of Bruchus obtedus —Continued 
LARVAE 
Tem¬ 
pera¬ 
ture 
at 
start 
j 
Time 
taken 
to 
reach 
0°C. 
Time 
taken 
to 
reach 
super¬ 
cooling 
point 
Rate 
at 
which 
insect 
was 
cooled 
Super¬ 
cooling 
point 
Re¬ 
bound 
point 
Remarks 
i 
i 
j 
°C. 
15 
Seconds 
19 
Seconds 
48 
Degrees 
per 
minute 
0.35 
°C. 
-10.20 
° C. 
-7.20 
Less than quarter grown. 
15 
20 
48 
.34 
-9.50 
-5. 50 
Full grown. 
-2.5 
24 
.36 
-8.75 
-5. 50 
Half grown. 
3 
8 
39 
.28 
-8.80 
-5.25 
Full grown. 
1 
2 
27 
.35 
-8. 75 
-6. 60 
Do. 
15 
30 
62 
.25 
-8.00 
-4.00 
Two-thirds grown. 
-3 
33 
.28 
-9.20 
-5.10 
Half grown. 
9 
11 
31 
.42 
-8.40 
-4.40 
Full grown. 
12 
24 
54 
.28 
-8.30 
-6. 75 
Quarter grown. 
10 
14 
60 
.29 
-13.25 
-9.75 
One-third grown. 
7 
10 
52 
.29 
-12. 50 
-11.00 
Quarter grown. 
11 
12 
32 
.50 
-10.00 
-7.50 
Two-thirds grown. 
-3 
14 
.66 
-9.30 
-5.25 
Do. 
15 
23 
50 
.32 
-8. 75 
-6.10 
One-third grown. 
7 
11 
31 
.45 
-9.00 
-6.50 
Full grown. 
14 
15 
48 
.30 
-10.00 
-7.25 
Do. 
19 
39 
70 
.40 
-12. 50 
-8.80 
Do. 
3 
2 
8 
1.96 
-11. 75 
-8. 60 
Quarter grown. 
16 
20 
70 
.24 
-12.00 
-6.10 
Full grown. 
19 
9 
26 
.66 
-11. 25 
-7. 75 
Do. 
10 
4 
9 
2.00 
-10.00 
-5.00 
Two-thirds grown. 
3 
5 
1.92 
-9.60 
-4. 50 
Half grown. 
18 
5 
10 
2.05 
-10. 25 
-7. 75 
Do. 
19 
5 
‘ 10 
1.80 
-9.00 
-6.00 
Do. 
3 
7 
2.31 
-9. 25< 
-4.75 
One-third grown. 
Average 
-9.53 
-6.52 
The averages in Table I are brought together here for convenience 
of reference: 
Adults 
Pupae 
Larvae 
Supercooling point__ 
Rebound point__ 
°C 
-8.68 
-5.55 
°C 
-9.22 
-5.12 
°C 
-9.53 
-6.52 
This shows a progressive lowering of the supercooling point from 
adults to larvae. The differences between these are slight, and may 
find their explanation in the metamorphic differences existing be¬ 
tween these three stages. It is interesting to note that the super¬ 
cooling point is depressed in the purely vegetative larvae and is high¬ 
est in the adult. It should be noted, however, that in the case of 
the unemerged adults much greater uniformity of development is 
found than m any of the more immature stages. These first named 
were all obtainable at a point just previous to emergence. The pupae 
on the other hand, presented variations due to differences in the 
progress of histolysis and histogenesis, while the larvae were in all 
stages of growth, from very small specimens just big enough to con¬ 
tain the thermocouple point to full-grown larvae full of fat body. 
Reference to Figure 1, B, will show that while the general trend of 
the curve is similar to those of Figure 2, A and C, the points are more 
widely separated. This suggests that individual differences among 
pupae are due to differences in kind while those of the larvae are dif- 
