A pest to gardeners, slugs play key role in Pacific Northwest

Among the Pacific Northwest’s iconic animals is the slug – a slimy and repulsive-looking creature that’s the bane of home gardeners but performs a key function in the region’s temperate rainforest climate.

“They are basically snails without shells. They are a stomach on a foot,” said Beth Chisholm, community horticultural coordinator for Washington State University’s Whatcom County Extension.

She said slugs are decomposers, animals that break down vegetation, turning it into the rich soil that feeds the Northwest’s native forests.

“Decomposers eat things. (Slugs) love to eat the things we love to grow. But they are helpful in turning things into soil,” Chisholm said.

Chisholm emphasized that she was referring to the native banana slug that’s found in forests, not the invasive European brown slug, which is found in urban areas.

Banana slugs are gastropods that range from southeast Alaska to Santa Cruz in Central California, where they are often bright yellow. In Northwest Washington, banana slugs are more likely to be olive green or brown with darker spots.

They’re hermaphrodites, exhibiting the characteristics of both males and females.

“The lovely thing about the banana slug is their ability to be both girls and boys at the same time,” said Holly Roger of Wild Whatcom, a local outdoors education organization.

“They’ll be out by April or May, after spending the cold winter months hiding in a deep sleep.”

Roger said slugs have two sets of appendages called tentacles to sense their surroundings. The upper pair is their eyes, and the lower pair is for touch and taste.

Their foot is also their tongue, and it’s covered in tiny teeth. They emit slime to protect their delicate bodies from dehydration.

“It leaves a track wherever its goes, a beautiful rainbow slime,” Roger said. “They need to eat forest debris and break it down. They’re important especially for the spread of mushroom spores.”

Chisholm agrees.

“They’re pests for the normal gardener, but they’re beneficial for their part of the food chain. They are known to be pretty tasty to thrushes, starlings and ducks,” she said.

“They eat our favorite plants, but they are decomposers. They do help us. They’re not all bad. When it comes to their purpose, they definitely have a niche in our local habitat. They do the silent work for us. But occasionally they do some damage.”

This story was originally published March 14, 2017 at 7:00 AM with the headline "A pest to gardeners, slugs play key role in Pacific Northwest."