“MEXICAN BEAN BEETLE IN THE SOUTHEAST. 19 
The largest numbers of hibernating beetles have been found in 
woodlands where the land is rolling. In all cases where living 
beetles were taken, the material sheltering them was moist and was 
protected from driving winds. As this material dried out, during 
warm weather, the beetles moved about and went farther into the 
material where moisture was present, or migrated to more favorable 
quarters. 
In sections where the infestation is extremely heavy there is a 
tendency toward hibernating gregariously. About Birmingham, 
Ala., in the winter of 1921-22, 56 per cent of the 2,290 beetles 
observed were found in colonies. The following winter, 1922-23, 
only 14.8 per cent as many beetles were found per unit of area as 
| during the previous winter. This was probably due to the lighter 
infestation during 1922. | 
The largest colony observed contained 329 beetles on December 
15, 1921, and the majority of beetles occurred in a space 18 inches 
square. The colony shown in Plate X, A, B, contained 149 beetles, 
more than 50 of which were in a space less than 1 foot square, about 
1 inch below the surface. This colony was under pine needles and 
oak leaves which had accumulated under a pine branch on the 
- ground. 
During cold weather in January adults withstood submersion in 
water for two days with no mortality. Fifty per cent of the beetles 
survived after submersion for four days, and one beetle was living 
after six days. Insmall hibernation cages which were not sufficiently 
| moist all beetles succumbed. 
Males and females occur in approximately equal proportions. 
The few beetles which remain in the bean fields during winter 
are undoubtedly a factor in the spring infestation, but the large 
majority of adults migrate from the fields to wooded hills. The 
proper moisture conditions for successful survival of the winter 
appear to be an important factor in determining the location chosen. 
These conditions are only constant under branches and leaves in 
the shade, or in deep piles of material. The preferred material in 
the Southeast is a mixture of pine needles and oak leaves. (Pl. X.) 
The beetles are found distributed through the material at a depth 
of an inch or more, depending on the moisture conditions. Adults 
are occasionally found with colonies of the beneficial ladybird, — 
Megilla maculata DeG. — 
October 3, 1922, three beetles were observed in hibernation in 
_ woodlands when the shade temperature was 82° F. Three days 
_ later 25 beetles were found in the same place. 
During the mild winters of the Southeastern States the adults 
are not entirely inactive. On warm days they move about, and in 
the course of the winter the majority change location. Some of 
the colonies of beetles found in woodlands were watched throughout 
the winter. Each beetle was marked with a waterproof mark. 
_ Brief records of the observations are given in Tables 6 and 7. 
