Editors: W.T. Wilsey, C.R. Weeden, and A.M. Shelton

Mexican Bean Beetle (Epilachna varivestis) - Life Cycle

Click for larger image	Adults: The adult Mexican bean beetle is about 1/4 inch (6 mm) long, very convex and short in form. It varies in color from yellow when newly emerged from the pupal stage to a coppery-brown when mature or in the overwintering stage. Each wing cover had eight black dots in three rows across the back when the wings are at rest. When disturbed, the adults fall from the plant and exude a yellow liquid from their leg joints. The adult beetles pass the winter under trash and other ground cover along hedgerows and in similar protected places.	Click for larger image
	Eggs: After feeding 1-2 weeks on the preferred host crop of beans, the adults deposit eggs on the underside of the leaves. The eggs are about 1/20 inch (1.2 mm) long, orange-yellow in color and fastened on end in close groups of 40-50 or more. The eggs hatch in 5-14 days depending on temperature.
	Nymphs: The nymphs are yellow in color and the body is covered with six rows of long, black-tipped spines. The larval stage lasts for 2-5 weeks: when full grown the larvae or grubs are 1/3 inch (8 mm) long. Pupation takes place on the bean leaves.
	Pupae: The pupa is orange in color and is attached to the leaf by the old larval skin. The adult emerges in approximately 10 days. The total period of development from egg to adult averages 33 days under midsummer conditions.

Damage inflicted by Mexican bean beetle on beans

Some information on this page taken from Insects of Beans: Cornell Coopertive Extension factsheet number 139VCFS770.00 authored by A. A. Muka.

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Maintained by Jason D. Plate. Last updated Mar. 8th, 2007.