Spotted Garden Slug

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SLUGS AND SNAILS
Spotted Garden Slug

DESCRIPTION

Adult -

An adult spotted garden slug is 80 to 150 mm in length. The body color is usually yellowish gray, but may be brown. There are two or three darker rows of spots or strips on each side. The mantle is only on the anterior end of the animal, it is concentrically wrinkled, without a groove, the breathing pore is located in the posterior half of the mantle. The body is keeled only near the posterior end. Both the body and the mantle have large black spots. The mantle and body are often banded, and the foot fringe has small black grooves. The mucus is colorless and sticky.

Eggs -

The light yellow eggs are laid in clusters of about 25 in the soil.

Young -

Young slugs are about 14 mm long at hatching. They are usually dull white when they hatch. A few hours after hatching the body begins to darken and in about two days it is brownish in color. The body darkening lasts about a month, at which time the black spots begin to appear (the slug is about 25 mm. long now). Immature slugs remain together in a colony near where the eggs are deposited for four to five weeks.

Fig 144 Spotted garden slug, Limax maxumus Limacidae, STYLOMMATOPHORA

BIOLOGY

Distribution -

The spotted garden slug was introduced into the United States from Europe. In this country it is recorded from Massachusetts south to Georgia and west to Oregon and California.

Host Plants -

Spotted garden slugs feed on lilies, iris, and narcissus in greenhouses and bedding plants outdoors.

Damage -

This slug leaves a trail of slime wherever it goes. It eats large ragged holes in the leaves of mature plants and may completely devour small seedlings. They usually are most serious on plants growing close to the soil surface.

Life History -

The spotted garden slug lays clusters of about 25 light yellow eggs covered by mucus (674 to 834 total). Eggs are usually deposited under objects on the ground such as stones and boards. Eggs hatch in about 30 days at 24°C (sooner at higher temperatures). Immature slugs remain together in a colony near where the eggs are deposited for four to five weeks.

Activity is greatest during the night and on damp, cloudy days. Spotted garden slugs prefer temperatures of 21 to 27°C. They can survive 30 to 34°C for a short while, but they immediately seek shelter to conserve moisture. These slugs regulate body temperature by evaporation of water from the skin (maintaining up to 12°C difference). They often feed and hide among the leaves of large-leafed plants. Outdoors they are among the first pests to begin feeding in the spring and among the last to stop feeding in the fall. Indoors they will feed as long as environmental conditions are favorable. In damp soil they tend to be solitary, but in dry soil spotted garden slugs bunch together. They may live 30 to 36 months.

CONTROL

Spotted garden slugs can loose up to 50 per cent body weight and recover after 2 hours of exposure to water. Thus if poisoned with metaldehyde, spotted garden slugs may recover if they have access to water.

For chemical control recommendations, see the current Cooperative Extension publications on ornamental plant pest management or consult your county Extension agent.

Reference to University of Florida/IFAS