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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 15 



have been observed under good drainage conditions, but usually consid- 

 erable moisture is present. As hibernating material dries out, the bee- 

 tles seek a moist location and go deeper under the leaves. On warm 

 days they become active. 



A few beetles have been found hibernating 1 mile from the nearest 

 bean field, 25 individuals three-fourths of a mile from the nearest field, 

 and large numbers one-fourth and three-eights of a mile from the 

 nearest fields. The majority of those observed, however, were within, 

 one-fourth of a mile of bean fields which had been destroyed.' 



From information gained in 1921, it is evident that a "clean-up"' 

 practice which merely includes the garden patch or small farm is not 

 likely to be of great value. A few beetles always occur in gardens and 

 bean fields, but may be considered stragglers. 



Table 4 gives the length of life of the adults, by generations, obtained, 

 from first eggs of first pairs in each case, which were checked with field 

 cages, from insectary records. 



This species may be considered a double-generation insect in the 

 Southeastern United States, while it is a single-generation insect in 

 the Western and Southw^estem United States, and probably in many 

 parts of old Mexico. In Alabama it could undoubtedly survive, however,, 

 with one generation under certain conditions. Owing to a retarded 

 issuance from hibernation of a certain percentage and because of the 

 longevity of the beetles, there is an overlapping of generations, which: 



Table 4. — Length of Life of Adults of the Mexican Bean Beetle 



^Early in April, 1922, Mr. J. E. Graf, Bureau of Entomology, accompanied by 

 Mr. J. G. Hamilton of Torrance County, New Mexico, found the Mexican bean 

 beetle hibernating 17 miles west of Estanica in loose colonies in piles of oak leaves, 

 and pine needles, 73^ miles from any bean fields. Beetles in trash near bean fields, 

 were extremely rare. 



