| Sumario: | The morphology, biology and habits of the chrysomelids Diabrotica balteata Leconte and Cerotoma facialis Erickson as pests of common beans are described following laboratory (27°C 80% R H.) and greenhouse studies. It was found that larvae of D balteata do not survive when feeding on bean roots, and C. facialis will not attack maize seedlings. Eggs of D. balteata and C. facialis lasted an average of 5:1 and 6.4 days, respectively. Both species have three larval instates which are passed in 14 days in the case of D. balteata and 10.6 days for C. facialis. Pupae form in a cell in the ground and this stage lasts from 6 to 7 days. In both species the sex ratio was 1,1. When fed bean foliage, females lived an average of 37 days (Diabrotica) and 52 days (Cerotoma) In both species the preoviposition period varied from 5 to 12 days.
77he maximum egg production by adult D. balteata that fed on bean leaves was 144 per female; C. facialis females laid up to 532 eggs. Both species consume more foliage during the first two weeks of their lifespan.
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