{"id":24927,"date":"2022-07-20T15:17:31","date_gmt":"2022-07-20T15:17:31","guid":{"rendered":"https:\/\/prograin.ca\/ca\/?p=24927"},"modified":"2025-03-27T17:19:54","modified_gmt":"2025-03-27T17:19:54","slug":"the-bean-leaf-beetle-and-soybeans","status":"publish","type":"post","link":"https:\/\/prograin.ca\/ca\/en\/2022\/07\/20\/the-bean-leaf-beetle-and-soybeans\/","title":{"rendered":"The Bean Leaf Beetle in Soybeans"},"content":{"rendered":"\n

The Bean Leaf Beetle is an increasingly common insect pest in the soybean fields of Qu\u00e9bec and Eastern Ontario.<\/p>\n\n\n\n

Identification<\/h2>\n\n\n\n

Adults are usually yellow, tan, or red in color, with black and yellow legs. The head is black and antennae are yellow with dark tips. The body is characterized by rectangular black markings and an inverted triangle of the same color behind the neck. They measure approximately 5 mm.<\/p>\n\n\n\n

Eggs are oval-shaped and may be red, orange, or yellow. They measure 0.80 mm by 0.35 mm. The mature larva measures approximately 10 mm in length; their bodies are beige, and dark at both ends. They have three (3) pairs of legs near the head and one fleshy \u201cproleg\u201d on the last abdominal segment.<\/p>\n\n\n\n

Life cycle<\/h2>\n\n\n\n

Adult bean leaf beetles overwinter in grassy edges of fields or leaf debris. They emerge in May or June when the weather warms up. They also mate at this time and will lay 250 to 300 eggs at the base of soybean plants. The eggs hatch in about 10 days on average.<\/p>\n\n\n\n

The overwintering bean leaf beetles produce one generation a year in Qu\u00e9bec. The previous season\u2019s beetles die in late June to make way for the next generation. The new larvae undergo three growth stages over the course of 18 to 24 days and transform into nymphs (pupa). The nymphs remain underground for seven (7) days and then emerge as adults.<\/p>\n\n\n\n

Damage<\/h2>\n\n\n\n

Beginning in spring, the overwintering generation of bean leaf beetles feeds on the leaves of the soybean plant, leaving holes between the leaf veins. They also attack the cotyledons and new seedlings.In July and August, it is the turn of the new adults to damage the leaves, and the pods as well. <\/p>\n\n\n\n

As a result, the seeds themselves will be affected in multiple ways, as the damaged pods will expose the seeds to damp or dry conditions, or to injury leaving them vulnerable to fungal diseases. Bean pod mottle, caused by a virus transmitted by the bean leaf beetle, can also affect seed quality.The larva can cause root damage.<\/p>\n\n\n\n

Scouting adult beetles<\/h2>\n\n\n\n