Mexican Bean Beetle
Adult - The Mexican bean beetle is (1/2 to 5/8in) or (6 to 8.5) mm long and dome shaped. Overwintering beetles are lighter in color. Each wing cover has eight small black spots that form three rows across the body when the wings are at rest.
Egg - The yellow egg is about 1/32in or 1.3 mm long and elliptical in shape.
Larva - The mature yellow larva is about 5/8 in or 8.5 mm long and covered with dark, branched spines.
Pupa - The yellow- to copper-colored pupa is about 1/2 in or 6 mm long. It moves very little and has fewer spines than the larva.
Distribution - Formerly, the Mexican bean beetle was limited from Colorado southward. It is now common throughout the U.S. with the exception of the Pacific Coast states.
Susceptible Plants - Mexican bean beetles have a wide host range. They are most commonly encountered on garden and field beans as well as cowpea. Soybean, clover, alfalfa, and closely related weeds may also be attacked.
Symptoms - The Mexican bean beetle is the most injurious pest of beans (snap, lima, pole, kidney, pinto, navy, bush). If overwintering populations are high, seedling damage may occur, though economic damage usually does not occur before August. Both larvae and adults feed on leaves, leaving the upper surface intact. Damaged plants have a characteristic lace-like (skeletonized) appearance. These remaining tissues die in about 2 days and turn brown, often giving the entire field a "burnt" cast. Pods and stems are often attacked, and shredded plants may die before any crop is matured.
Life Cycle - Adult Mexican bean beetles overwinter in hedgerows, ditchbanks, and woodlands and may attack plants soon after seedlings emerge in spring. Most beetles leave their winter quarters over a 2-month period. Following feeding, adult females deposit eggs in clusters of 40 or more on the undersurface of leaves.
Eggs hatch in 5 to 14 days and larvae continue to feed for 2 to 5 weeks. Larvae pupate on leaves and adults emerge after about 10 days. Adults feed, mate, and lay eggs over a period of 2 weeks. Generation time from egg to adult is about 30 days. In warmer climates there are three or four generations each year.
Prevention and Control- Snap bean varieties such as Wade, Logan, and Black Valentine are generally less severely damaged than other varieties by the Mexican bean beetle. Since damage is usually most severe during July and August, very early maturing bean varieties and fall plantings may be grown with little injury. Prompt removal of pods and destruction of old plants are suggested as insurance against Mexican bean beetle population buildup. Cover plants with row covers
or a Summerweight Garden Fabric
until they are large.
Biological Control- Release spineed soldier bugs to control the early generation. release Mexican Bean Beetle Parasite Pediobius faveolatus 20 Mummies , a parasitic wasp when the weather warms.
More Products to Control Mexican Bean Beetle
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| Bonide Pryethrin $19.95 |
Praying Mantis Egg Case (6) $24.00 |
Predator Nematodes 1million $15.44 |
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