Crazy Worms in Maine

Crazy Worm and Nightcrawler, Photo courtesy Wisconsin DNR

What are Crazy Worms?

Due to our history of glaciation, there are no native earthworms in Maine. Non-native earthworms from Europe (such as nightcrawlers) have become well established here through early colonial trading. Though they are beneficial to our gardens, earthworms can have destructive effects on our forests.

Crazy worms are a type of earthworm native to East Asia. They are smaller than nightcrawlers, reproduce rapidly, are much more active, and have a more voracious appetite. This rapid life cycle and ability to reproduce asexually gives them a competitive edge over native organisms, and even over nightcrawlers. When disturbed, crazy worms jump and thrash about, behaving like a threatened snake.

Crazy worms are known and sold for bait and composting under a variety of names including snake worms, Alabama jumper, jumping worms, Asian crazy worm. They are in the genus Amynthas, and distinguishing between the several species in the genus can be difficult. All species in this genus are considered invasive in Maine. It is illegal to import them into Maine (or to propagate or possess them) without a wildlife importation permit from the Maine Department of Inland Fisheries and Wildlife (MDIFW). For more information, visit MDIFW's Fish & Wildlife in Captivity webpage.

History in Maine

Crazy worms are native to Korea and Japan, and are now found in the United States from Maine to South Carolina and west to Wisconsin. Crazy worms were first collected from a Maine greenhouse in 1899, though an established population of this active and damaging pest was not discovered here until about 2014 when two populations were discovered in Augusta (one at the Viles Arboretum) and two populations were found in Portland. They have also been found in a rhododendron display at the Coastal Maine Botanical Gardens in Boothbay. We believe that crazy worms are not yet widespread in Maine, but they have been discovered in some new locations since 2014, including nursery settings. If allowed to spread, crazy worms could cause serious damage to horticultural crops and the forest ecosystem in Maine.

Why are Crazy Worms a Problem?

Crazy worms change the soil by accelerating the decomposition of leaf litter on the forest floor. They turn good soil into grainy, dry worm castings (aka poop) that cannot support the native understory plants of our forests. Other native plants, fungi, invertebrates, and vertebrates may decline because the forest and its soils can no longer support them. As native species decline, invasive plants may take their place and further exacerbate the loss of species diversity.

In nurseries and greenhouses, crazy worms reduce the functionality of soils and planting media and cause severe drought symptoms. After irrigating or rains, you may find these worms under pots. These worms may be inadvertently moved to new areas with nursery stock, or in soil, mulch, or compost.

Many of Maine's forests are already under pressure from invasive insect pests, invasive plants, pathogens, and diseases. Crazy worms may cause long-term effects on our forests.

Crazy Worm clitellum, Photo courtesy University of Illinois

Crazy Worm Identification

When handled, they act crazy, jump and thrash about, behaving more like a threatened snake than a nightcrawler, Video of jumping worm wriggling

May shed their tail when handled, Video of jumping worm tail detachment

Clitellum (the band around their body) is milky white, smooth, and flat to their body

Often found in groups

Soil looks very grainy at the surface, like coffee grounds

Can reproduce by parthenogenisis (asexually), maturing in 60 days, allowing two hatches per season

Annual species, but tiny cocoons overwinter in the soil

Best time to find them is late June to mid-October

In nurseries, they can often be found underneath pots that are sitting on the ground or on landscape fabric

In forests, they tend to be near the surface, just under accumulations of slash or duff



Crazy Worm cocoon at yellow arrow, in granular castings, Photo by Marie Johnston, courtesy University of Wisconsin-Madison Arboretum

What can you do?