Some do, but slugs are surprisingly adept at surviving freezing conditions – very low temperatures do not have a particularly negative impact on overall numbers for the following year.
In winter, slugs seek out thermally buffered hibernation sites where temperatures rarely dip below 0°C. These are usually underground and provide protection from the worst winter frosts.
Studies also show that even if slugs are directly exposed to frost crystals, both juveniles and adults of most species are able to withstand the formation of extra-cellular ice in their tissues for a limited time.
Slug eggs also overwinter in large numbers, probably surviving the chill by ‘supercooling’ – lowering their normal freezing points.
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