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Soybean Pest Forecasting

Several insect pests cause significant damage to soybeans, dry beans, and edible beans. Some insects, such as bean leaf beetles also transmit viral diseases. Several bean pests overwinter in Ontario and few of them move from the south. The life cycles of these pests are driven by temperature. Using knowledge of pest biology and growing degree day-based threshold, scouting advisories are deployed for four economically important pests of beans: (i) Bean Leaf Beetles, (ii) Japanese Beetles, (iii) Potato Leaf Hoppers, (iv) Seed Corn Maggots. Register your soybean fields to get site-specific pest advisory for the crop.

Click the insect name to get information about these pests.

Bean Leaf Beetles

Bean leaf beetle (Certoma trifurcate) cause significant damage to soybeans, snap beans, and dry beans. More importantly, the insect transmit bean pod mottle virus disease. The adult overwinters in soil debris, leaf litter, and woodlots during winter months. Once the temperature rises in the spring, the over-wintering adults emerge and feed on forage crops in the surrounding area and migrate to soybean to lay egg and feed soybean plants. The second generation beetle feed on foliage and bean pods and causes both yield and quality loss.

Key Diagnostic Features

Adults of bean leaf beetles are small, 5 mm in length. The adults might be yellow, orange, tan or red in color and mostly have black triangle on the base of wing. Some beetles might not have black spot on the wing cover. The adults might be often confused with spotted cucumber beetle or lady beetles.

BeanLeafBeetle1 BeanLeafBeetle2 BeanLeafBeetle3
An adult of bean leaf beetle            Foliar damage from beetles          Pod damage from beetles

Japanese Beetles

Japanese beetles (Popillia japonica) also an economically important pest of soybean and other field crops including corn and dry beans in Ontario. The adults feed and destroy both foliage and pod of soybean. In addition, this pest also infests about 250 host including several tree fruits and berries.

Japanese beetles have only one generation in a year in Ontario. The beetles overwinter in Ontario. Both larvae and adults cause damage to soybean, corn and other field crops. Larvae also feed on roots. Once the temperature rises above 15°C, the activities of larvae will begin and feed on the roots of field crops. The adults emerge on mid-summer and cause damage on soybean foliage and pod. It also clips the silk of corn.

Key Diagnostic Features

Larvae: The beetle grubs have wide, shallow V-shaped raster pattern in abdominal segment.

Adults: Adult beetles have bright metallic-green head and coppery wings with green edges.

japs1 japs2

Seed Corn Maggots

Seed corn maggots (Delia platura) also infest soybean seedlings as it infests seedlings of seed corn. The larvae (maggots) feed on seed, seedlings and roots at early stages of the soybean, which cause poor germination and reduce the numbers of soybean stands in the field. Low (cool) temperature and wet field conditions are more favorable for seed corn maggots infestation in fields.


Potato Leafhoppers

The potato leafhopper (Empoasca fabae) is one of the economically important pests of soybeans. The insect infests more than 100 plant species including potatoes, soybeans, dry edible beans, alfalfa, and clover. The insect frequently moves from one crop to another. Potato leaf hoppers lay egg on soybean and nymphs feed on soybean foliage. The insects can complete a life cycle within months and have multiple generations per year in Ontario.

Key Diagnostic Features

Adults are small, lime green and cylindrical. The nymphs are wingless and smaller than adults. Both adults and nymphs cause damage to crops.


* To access site-specific insect scouting advisories and management guidelines, login or register and plot your soybean field.