CONSUMPTION OF ALFALFA BY ADULT ALFALFA WEEVILS (COLEOPTERA, CURCULIONIDAE)

Adult H. postica (Gyllenhal) had 2 primary feeding periods [Utah, USA]. Newly matured weevils fed during midsummer, and old, overwintered weevils fed after returning to the fields the following spring. During each feeding period, weevil adults ate more, started feeding sooner, and reached feeding peaks sooner with each increase in temperature between 16.7.degree. and 27.8.degree. C. At 27.8.degree. C, old weevils completed their feeding in about half as many days as at 22.2.degree. C. At 27.8.degree. C, each old adult ate an average total of 12.7 mg (dry weight) of alfalfa, and each new adult ate 22.6 mg (dry weight) of alfalfa. When data from old and new adults from the same generation were combined, each adult weevil ate .apprx. 4.5 times as much as each larva, or .apprx. 35.3 mg (dry weight). In field cages, new adults during their peak feeding activity consumed new growth of alfalfa plants after harvesting and reduced the length of the old stems. Five new adults per plant prevented most new growth; 20 adults per plant killed the plants.