Saving seeds? Look out for this new non-native insect

By: Marissa Schuh, Horticulture IPM Extension Educator

With the end of the growing season on the distant horizon, those saving seeds for themselves or for others should be on the lookout for a pest with the potential to hurt seed production - purple carrot-seed moth.

What is purple carrot-seed moth?

Purple carrot-seed moths are a small, generic moth native to Europe and Asia.  The immature, caterpillar life stage feeds on seeds and flowers of plants in the family Apiaceae, which includes herbs and vegetables like carrots, celery, parsley, cilantro, dill, and fennel.   They were first reported in the US in 2008, and have been found in neighboring Midwestern states in recent years. They were first reported in Minnesota (Washington County) earlier this summer.

Purple carrot-seed moth larvae can be found feeding together.  They are small, produce webbing,  and have white spots. Photo: Minnesota Department of Agriculture

The small caterpillars (¼ inches) feed on flowers.  They may group together a couple of small flowers in silk webbing.  The silky clumps of flowers are often more obvious than the caterpillars or feeding itself.

Purple carrot-seed moth on a penny. Photo: Jody Green, University of Nebraska-Lincoln.

What kind of damage does purple carrot-seed moth cause?

This species only feeds on flowers and seeds.  This means that celery stalk or carrot root are safe, but if you are trying to save seed, either for growing or to make dried spices, carrot-seed moth may cause issues.

Damage can be hard to spot, as these are small caterpillars feeding on small flowers. Photo: Shane Bugeja, UMN extension

How much damage can it cause? 

It is hard to say.  There have not been any reports of major damage in the US, but growers producing seed should keep an eye out.

What should I do if I see purple carrot-seed moth?

These insects are easy to remove or squish by hand.  The flowers they are on can be easily plucked, and the caterpillars can be killed by placing them in a bucket of soapy water.   Insecticidal soap. Neem, and the kurstanki Bt strain should also be effective.

The Minnesota State Department of Agriculture keeps track of where non-native and invasive species have been spotted. If you suspect that you’ve seen purple carrot-seed moth, report it to the state via email at Arrest.the.Pest@state.mn.us or by phone at 1-888-545-6684, or use the MDA’s online form.