Wisconsin crop fields have been largely free of major insect outbreaks so far this season, but entomologists warn that could change as heat and moisture levels rise. Krista Hamilton with the DATCP Pest Survey Program says the second half of summer brings a new set of insect threats. Scouting in late July and early August should focus on rootworm beetles, second-generation armyworms, and corn earworm flights. Soybean growers should keep a close eye on aphids, Japanese beetles, and other defoliators, as multiple pests may begin to peak at once.

Japanese beetles, in particular, are drawn to emerging corn silks and can cause serious damage if left unchecked. Hamilton says feeding is typically concentrated in the first few rows of a field, making targeted treatment effective. For soybeans, aphids are just beginning to colonize and multiply. Weekly scouting is essential now, especially if aphid numbers approach the treatment threshold of 250 per plant. While armyworm activity is currently low, Hamilton advises keeping them on the radar as second-generation populations can spike later this month.

Pictured: Japanese beetles

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