MEXICAN BEAN BEETLE — ^WHITE 349 



lished whether the insect infested soybeans, cowpeas, and other legumes 

 that were so important to the agriculture of the East. Studies on 

 host plants soon revealed that its favorite foods were the common 

 varieties of garden bean, tepary beans, and limas, which are grouped 

 under the species Phaseolus vulgaris and P. lunatus. This food pref- 

 erence distinguished the insect as a pest of the hom.e garden, and its 

 fondness for and ability to thrive particularly on the "corn field," 

 or pole bean, eliminated this important source of food to the home 

 garden of the South during years when the insect was most abundant. 



It can live and develop on certain other food plants. Next to beans, 

 it prefers beggarweed or beggartick, a plant of the genus Meihomia. 

 Its next choice is the hyacinth bean, followed in order by the cowpea 

 and soybean. It may also feed to a limited extent on the adsuki bean, 

 kudzu, and some clovers. In the early part of the season the insect 

 does not, and apparently cannot, live on some of these latter-named 

 plants, especially cowpeas and soybeans, whereas later in the season 

 it seems to thrive on them. It has been only in comparatively rare 

 instances that cowpeas and soybeans have been injured in the field, 

 and in these cases it was observed that the beetles developed in large 

 numbers on adjacent garden beans and overflowed onto the soybeans 

 and cowpeas after their favorite food had become exhausted. Under 

 threat of starvation it may be forced to feed on many types of plants, 

 such as okra, eggplant, and squash. However, attack on these garden 

 plants is rare, and the bean beetle has proved to be primarily a pest of 

 garden beans. 



Life history. — The bean beetle resembles in form and color some 

 of the native beneficial ladybirds, to which family of insects it belongs. 

 In form it is rounded, about one-fourth inch long and one-fifth inch 

 wide; each brown or copper-colored wing cover bears eight distinct 

 black spots. The immature form, or larva, is orange-colored; when 

 full grown, it is about one-third inch long and is covered with com- 

 paratively long, soft branched spines, which give it a fuzzy appear- 

 ance. The insect overwinters in the adult stage and prefers for win- 

 ter protection a mixture of oak leaves and pine needles, located on 

 woody slopes. With the approach of cool weather they congregate 

 in such locations, crawling to a depth of several inches among the 

 cover, where they will not be subject to rapid fluctuations of moisture 

 and temperature. In the southern States the beetles may be found 

 active during the warm days of the winter and in some instances may 

 seek locations different from those originally occupied with the ap- 

 proach of cold weather. A few may remain and successfully over- 

 winter in the old bean fields, but the majority will be found in nearby 

 woodlands. 



The overwintering beetles appear in the field at about the time that 

 the earliest beans show their first true leaves. After feedins: for a 



