Invasive moth found for first time in Minnesota

An invasive moth that feeds on carrots has been found for the first time in Minnesota.

A resident near Stillwater first noticed the purple carrot-seed moth, also known as depressaria depressant, on their dill plants and reported it to the Minnesota Department of Agriculture. A second report from Montgomery came in a few days later. 

With help from the University of Wisconsin Diagnostic Lab, scientists made the identification from photos.

“The impact of this insect is currently unknown, but because it is associated with the flowers and not the roots of plants, impact on carrots, celery, and parsnip crops should be minimal,” said Angie Ambourn, supervisor of the MDA’s Pest Detection Unit. “Crops that are commonly grown for seed, like fennel, dill and coriander, might be where we see the greater impact.”

Purple carrot-seed caterpillars feed on the flowers, but they also tie the floral parts with webbing and can make herbs like dill unusable. 

The caterpillars are dark and distinctive and can be green or reddish with many white spots on their bodies, the agency said. They pupate in the webbing and emerge as small purplish-grey adult moths a short time later.

The moth is native to Western Europe, Russia and China and first discovered in North America in 2008. It has been documented in southern Canada, Michigan, Indiana, and Illinois. Most recently, it was discovered in Wisconsin in 2018 and Iowa in 2020.

Residents can report suspected purple carrot-seed moth to the MDA’s Report a Pest line by visiting www.mda.state.mn.us/reportapest or calling 1-888-545-6684.