22 BULLETIN 1243, U. S. DEPARTMENT: OF AGRICULTURE. C4 
7 
TABLE 7.—Data on colonies of Mexican bean beetles in hibernation, winter of — 
1922-23 (through Feb. 9, 1923)—Continued. 
GROUP 9. 
[81 beetles in original colony, in space 5 feet by 10 feei, marked black, Dec. 20, 1922. 
Number of | Number of 
Date. beetles beetles Remarks. 
painted. | unpainted. 
1922 
GOCE 202 Os BE ye Ns PR te ae cee AS Se 2 ee ee Site ee Be 
BC SO 3 Nee eke eR ON ee eee eee ee 31 15 | Slightly active. 
1923 
A Ea a3 Joe see Mak ee Ree ce Ng Oe ek eS ORE ae UR RR RS Be cs Oe 30 19 | Inactive. 
DRIAL Doak LE eS A ee re ee te See oho Nah ee iat ki See rae 29 19 | Slightly active. 
Jan sak. 325555. 228k t es cet eee A eee ee a ee ee ee 21 12 | Active. 
PHO bys QR a5 Cys ae ene caper ds yatta Racer Se Oe me es | 22 21 | Inactive. 
The mortality in the woods during hibernation is not as great as 
might be expected. Remains of beetles have been found which in- 
dicate the work of carabid beetles or other predacious enemies. The 
high mortality in-Group 2 (Table 6) is unusual. 
ecords of hibernation were also obtained from cages. At Bir- 
mingham, Ala., 17,800 beetles were placed in cage 1, and were given 
their choice of materials which had been found by Dr. W. E. Hinds 
to be satisfactory the previous winter. The materials used were 
wood, sticks, cornstalks, and bean vine débris, a fourth of the cage 
being left bare. The cage was placed under a small tree which 
shaded it about half the day. Beetles numbering 18,050 were placed 
in cage 2, similar to cage 1, and with similar materials, but in a loca- 
tion a mile and a half away, where the cage was not shaded. These 
cages were placed at an altitude of about 600 feet above sea level, in 
latitude 33° 31’ N. 
Observations were made of cage 2 at intervals during the winter. 
As noted in the field observations, many of the beetles moved about 
on warm days throughout the winter. 
Air temperatures were taken in the shade as observations were 
made. No beetles were observed to be out of the hibernating ma- 
terial below a temperature of 50° F., and very few were out at tem- 
peratures below 60° F. At 60° F. and above, up to 70° F., from 30 
to 200 beetles would crawl about the top of the material and on the 
sides of the cage, depending on the amount of sunlight. Above 70° 
F., the beetles became more active, and March 30, 1922, at 75° F., 
724 beetles were out and active. Early spring migration and issu- 
ance from hibernation probably took place under natural conditions 
about that date, although the first adult was not taken on beans 
until April 6. After March 20 the beetles in the cages were active 
at temperatures below 60° F. on some days. April 1, when the tem- 
yerature was 45° F., 124 beetles were out. Almost all the beetles 
fibariotad under the pile of wood and sticks, several inches below 
the surface, where the material was constantly moist. A few beetles 
hibernated in the bean vine débris. 
In the spring, about the time appearance on the earliest garden 
beans was expected, as indicated ie observations of beetles under 
natural conditions, beetles were removed as fast as they crawled on 
the sides of the cage. The emergence in the cages is given in Table 
