What kind of insects have been spotted in Wisconsin?
Because hemp is relatively “new” in the state, we’re still getting a feel for what our top insect pests will be. Between the UW Insect Diagnostic Lab and colleagues here at UW-Madison and at DATCP, the top hemp insect pests I’ve seen recently include the Eurasian Hemp Borer (Grapholita delineana), European Corn Borer (Ostrinia nubialis), Japanese beetle (Popillia japonica), Cannabis Aphid (Phorodon cannabis), Common Stalk Borer (Papaipema nebris), and a close relative of the common stalk borer known as the Burdock Borer (Papaipema cataphracta).
The Wisconsin Pest Bulletin recently also mentioned red-headed flea beetle as a minor pest of hemp. Of the pests I’ve encountered, the most severe damage seems to be from the Eurasian Hemp Borer. Caterpillars of the Eurasian Hemp Borer can tunnel into stems of hemp plants, so the critical control window is before the caterpillars tunnel into plants. This issue of the WI Pest Bulletin shared some information on timing and control products.
In terms of additional resources, I’ve seen a good article from the IPM Practitioner on hemp insect IPM, which discusses some of the key hemp pests: https://www.birc.org/IPMPCannabis.pdf. Whitney Cranshaw and colleagues at Colorado State have some good resources available for hemp insects. In general, a lot of the hemp insects present in Colorado could also be spotted here.