In no-tillage fields, slugs will actively feed on germinating seeds and plant embryos, especially if the seed furrow is covered by a moist surface residue. When such damage occurs in the seed furrows and soil surface is damp, the slugs often can be readily found near the site of damage. Since foliar injury is generally observed during the day when slugs are not active, the tell-tale sign that the damage was caused by slugs is the trail of dry mucus that remains from earlier movement by slugs across the foliage. In general, slugs prefer cool and wet conditions. The ideal temperature and moisture conditions for field slug activity is between 63 and 68 deg.
Slugs exhibit nocturnal behavior and prefer to feed after dark and before dawn.
However, they may become active following a rain. The occurrence of slug damage to field crops especially on corn and soybeans is directly associated with the reduction of tillage. The accumulation of soil surface residue associated with no-till cultivation provides an optimum environment for development of slug populations, especially when ideal temperature and moisture conditions prevail. Slug problems are uncommon in a field under either conventional or reduced tillage. Most field slugs pass through a single generation per year and generally overwinter in the egg stage.