Dry weather may kill up to 90 percent of slug eggs and young per year. Metaldehyde baits have been shown to attract slugs up to 1 meter away. Thus in dry weather, metaldehyde is more effective. In wet weather, slugs sometimes can absorb enough moisture to compensate for the water lost in mucus production and therefore recover from the effects of metaldehyde. However, if slugs consume too much metaldehyde, they do not recover.
Slugs seem to become more susceptible to carbamate pesticides as they mature.
Copper sulfate is toxic to slugs and slugs will not crawl across a barrier of copper metal or wooden surfaces treated with copper sulfate.