Invasive Slugs

Module 1 – Introduction

Class Learning Objectives

  • Learn about federal regulations on the transport of non-native slugs and snails
  • Learn the difference between non-native, naturalized, and invasive
  • Learn about resources for reporting non-native and invasive species
  • Learn the basics of slug biology
  • Learn about the species of slugs to watch out for and report
  • Learn about methods to control slugs


Federal Regulations for Slugs and Snails

Slugs and Snails are regulated through the USDA Animal Plant Health Inspection Service (APHIS). It is illegal for interstate or international transport of live slugs or snails. The general view by the USDA on many gastropods is that they are, or could be, potential plant pests or vector of diseases. The USDA will permit transport of live gastropods for a variety of reasons. This includes research purposes, educational use in classrooms, display in zoos as well as the importation for research and aquatic hobby trade. The USDA issues permits under the authority of 7 CFR 330. These are the same permits required for the transport of pest species, biocontrol organisms and noxious weeds.

Alaska’s gastropod fauna is poorly known, there are a number of pest species which have been established elsewhere that the USDA will not permit transport into the state. APHIS provides a Mollusk Decision Matrix for educators considering importing gastropods into the state.

Invasive or non-native

Numerous species of non-native slugs and snails have become naturalized in Alaska. It’s good gastropod habitat. But when does a non-native become invasive? That is a tough question. An introduced species is considered invasive when it does or has potential to cause some level of economic or environmental harm. There have been no formal studies of real or assessments of potential impacts introduced gastropods may have to Alaska. Some economic damage to agriculture and home gardens has been casually observed. Potential for damage from introduced gastropods exists, however we are presently unsure if and how much damage will occur. 

Slugs and snails are also slow, we are the way they get around. They may lay eggs on a plant which is moved or sold, or adults may hitch a ride on some fishing or camping gear. Slugs are hermaphrodites and can self-fertilize, so it only takes one to start a new population. Being left to their own devices, slugs and snails would expand into new areas very slowly and rarely. Prevention of transport is the most effective way to keep non-native slugs and snails where they are at.

Transporting a non-native slug or snail does not mean that the introduction will cause damage. Slugs and snails share many attributes that plant invasives have, they can reproduce very quickly on their own, they can be very damaging, and they are undesirable. Many introductions likely go unnoticed or overlooked for long periods of time and are only noticed when something changes, like the building of a new garden. Then that non-native population will likely act invasively.

Continue to Module 2