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Soybeans: Japanese Beetle
Excerpt from Agronomy Guide for Field Crops (Chapter 4)Order OMAFRA Publication 811: Agronomy Guide for Field CropsTable of Contents
DescriptionThe adult beetles are approximately 13 mm in length and can be easily identified by their bright, metallic-green head and coppery wings tinged with green edges. They have 12 white tufts of hair along the boundary of their wings. The larvae are white, C-shaped grubs about 2 cm in length.
Plate 62. Japanese beetles have a bright, metallic green head and coppery wings tinged with green edges. Twelve white tufts of hair appear at wing boundary. | Top of Page | Life HistoryJapanese beetles overwinter as larvae in the soil below the frost line. Once temperatures increase, larvae migrate closer to the soil surface, feed on plant roots and then pupate. Adults emerge from the soil late June to late July and remain active for about 30-45 days. Adults mate during this time, and the females lay their eggs in damp soil. During periods of drought, eggs may be laid in poorly drained ground, irrigated areas or fallow fields where loose soil allows for the easy deposition of eggs. Egg-laying continues until late July and August. Eggs hatch in about 2 weeks. Newly hatched grubs feed on the roots in the upper 10 cm of soil. By late September, grubs begin to migrate to below the frost line to overwinter. DamageGrub (larvae) damage in soybeans is usually minimal. Adult feeding causes leaves to appear skeletonized. Scouting TechniqueScout 20 plants in at least five areas and compare the damage found to Figure 4-5, Defoliation Chart for Soybean Leaf-Feeding Insects. | Top of Page | Economic ThresholdsIf the defoliation exceeds the thresholds in Table 4-20, Standard Damage Thresholds for Soybean Insect Defoliation, a rescue treatment may be warranted to prevent excessive yield loss. Management StrategiesChemical control is only recommended when populations and damage exceed economic thresholds. There are quarantine restrictions to the transportation of soil, manure, compost, tubers and grass sod from infested fields in several counties of Ontario and Quebec. Consult the Canadian Food Inspection Agency for further information on these restrictions. | Top of Page | Updates on Soybeans: Japanese BeetleNo updates available at this time. | Top of Page | Related links...| Top of Page | For more information:Toll Free: 1-877-424-1300 Local: (519) 826-4047 E-mail: ag.info.omafra@ontario.ca |
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