Cowpea curculio

Chalcodermus aeneus

Egg: The egg is oval in shape, and white in color. It measures about 0.9 mm long and 0.6 mm wide. Eggs are deposited in the pod of the host plant, or within the seed in the pod. The female deposits her eggs in feeding sites, with only a single egg deposited in each feeding puncture. Each female deposits, on average, about 112 eggs (range 30 to 280) during an oviposition period of about 45 days. Duration of the egg stage is about four (range three to six) days.
Larva: The larva is pale yellow in color, although the head and prothoracic plate are yellowish brown. The larva lacks legs, but bears deep furrows around its body. The body is thickest about one-third the distance between the head and anus, tapering gradually to a fairly pointed posterior end. The body bears stiff bristles. The larva attains a length of about 7 mm at maturity. There are four instars. Duration of the larval stage was reported to require about 9.4 days in Alabama, but only about six to seven days in Virginia. In the latter study, development times of the four instars averaged about 1, 1, 1, and 3.2 days, respectively.
Pupa: At completion of the larval stage the insect drops to the soil and burrows to a depth of 2.5 to 7.5 cm. During a prepupal period of about six (range three to 14) days the larva creates a pupal cell, and molts to the pupal stage. The pupa greatly resembles the adult in shape and size, but is yellowish white in color. Duration of the pupa is about 10 (range five to 19) days. After transformation to the adult, the beetle remains in the pupal cell for two to three days while it hardens, and then digs to the surface to emerge.
Adult: The adult is oval and robust in appearance. It is black in color, with a faint bronze tint. The mouthparts are elongate, slightly longer than the thorax, and only slightly curved. The thorax and elytra are marked with coarse punctures. The beetle measures 4.8 to 5.5 mm in length. Adults are most active during the morning and early evening, seeking shade during the heat of the day. They feign death and drop to the soil when disturbed. Beetles rarely fly. Adults overwinter in the soil and under leaves and other organic debris.

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