Experts Debate Leopard Slugs' Place in Urban Areas

Weather conditions have made this year a good--or bad--year for slugs--depending on your perspective. The Allegheny Front's Estelle Tran visited the Carnegie Museum to talk to some slug experts about the biggest and baddest slug in Pennsylvania, the Limax maximus.

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OPEN: Weather conditions have made this year a good--or bad--year for slugs--depending on your perspective. The Allegheny Front's Estelle Tran visited the Carnegie Museum to talk to some slug experts about the biggest and baddest slug in Pennsylvania, the Limax maximus.

(Turning on florescent light and opening doors)

TRAN: Tim Pearce, who heads the Section of Mollusks at the Carnegie Museum of Natural History, met me in the collection to talk to me about the Limax maximus, or the great slug, and to show me some slugs preserved in small jars of ethanol. Researchers keep thousands of preserved specimens behind old dark wooden doors with large glass panes. The slugs are preserved in little jars of ethanol.

PEARCE: These are some leopard slugs, and you can see the spots and the stripes.

TRAN: The Limax maximus is grayish-brown slug and can grow up to six inches long. Theyíre commonly called "leopard slugs" because of their dark spots.

Pearce says that the collection is important for scientists to understand what kind of species lived in the area at a time.

PEARCE: These very large ones are from Point Breeze, Pittsburgh, collected, I think, in 1978.

TRAN: Pearce says he has seen more slugs, though no leopard slugs, in his garden this year. He suspects the heavy winter snow kept the slugs warm underground, so more slugs made it through the winter.

TRAN: Leopard slugs are "city slugs" that prefer to be around people in urban areas instead of the suburbs or the woods. Though leopard slugs are non-native, theyíve been in this area for decades. Leopard slugs, like the earthworm, came from Europe. So, what are they doing here? In the lab of the Section of Mollusks, Paul Robb, a collections assistant at the museum, joins Pearce to share their differing viewpoints of these non-native slugs.

ROBB: It's been here a long time. I think it's been documented what 150 years at least. So as I like to say, I think it should get its citizenship papers. The fact that it doesn't invade the woods, for example, and just hangs around people, says something because there isn't that much for it to upset.

TRAN: Pearce believes leopard slug eggs probably came in the soil used as ballast for merchant ships. That could be why leopard slugs are more common in big cities. Even so, Pearce considers leopard slugs detrimental to human economies because they eat hostas, bok choy, cabbage and other garden veggies.

PEARCE: They're competing with us for our food that we're trying to grow. I have chosen to favor the native species in a land. To use the precautionary principle, maybe we don't have any evidence that the non-native slug is harming the natives, but just because we don't have evidence doesn't mean it's not happening.

TRAN: Though leopard slugs might not be harming native species, both Robb and Pearce can attest to their aggressiveness. Robb used to keep leopard slugs as pets.

ROBB: With the captive Limax maximuses I had here, there were numerous instances where I just saw one slug, the dominant slug if you will, just haul off and bite its cagemates.

TRAN: Leopard slugs have hundreds, if not thousands, of tiny teeth arranged in rows. If leopard slugs are biting your plants, you can bite back. Though Pearce is a vegetarian, he has sampled a leopard slug and some other slugs.

PEARCE: If you're interested in eating slugs, and you want to get the mucus of the snail or slug, the easiest way is to just put the slug into 50 percent vinegar and 50 percent water. It will give off a lot of the mucus. When you cook it, it won't make your cooking surface all slimey. If you are a gardener and you like organic methods, eating slugs is actually biological control.

TRAN: Though slug chowder isn't popular yet, the leopard slugís mating ritual is. On Youtube, hundreds of thousands of people have viewed leopard slug mating videos by BBC, Animal Planet and surprised observers. It's a feat of air acrobatics that just has to be seen. For The Allegheny Front, I'm Estelle Tran.