Archive:Poplar/Viceroy Butterfly
From Bugwoodwiki
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From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.
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Importance
Because the larvae live alone, little injury occurs during most of the growing season. However, late-season larvae feed on tender termites and buds, killing up to 10 inches of the growing tips, which results in multiple-forked crowns. Heavily injured trees are of little value. The viceroy is seldom important as a nursery pest.
Look For:
• Ragged partly consumed leaves near branch ends.
• Larvae up to 1½ inches long resembling an elongated bird dropping on the leaves. The body is a mixture of either olive green and white or brown and white. Two brown tubercles are on the thorax just behind the head.
• Orange and black butterfly resembling the Monarch butterfly, but smaller and with a narrow black line across each hind wing.
Biology
The number of generations per year increases from North to South. Eggs laid on the leaves produce larvae that feed solitarily on the leaves. When fully grown, the larvae from a brown and white chrysalis on the stem or branch. The adult butterfly emerges soon after and once again lays eggs on the leaves. In late fall, small larvae prepare to overwinter in rolled-up leaves.
Monitoring
Inspect young plantings in the first 3 years for injury and larvae in mid-summer. If 10 percent of infested trees show evidence of bud or shoot feeding, treat with an approved or registered insecticide.
Control
• Apply a commercial preparation of Bt (Bacillus thuringiensis) as soon as larvae are feeding.
• Spray infested trees with a chemical insecticide recommended for leaf-eating caterpillars.
