Pest identification
What's eating my oak fern?
Slugs and snails
Signs: Holes and notched frond edges on tender new growth; in damp woodland conditions slugs can cause patchy defoliation of young fronds
Control: Apply iron phosphate pellets or Phasmarhabditis nematodes in spring when fronds emerge; remove bark and stone debris where slugs shelter; avoid overhead watering in the evening
Caterpillars
Signs: Holes chewed from the centre of pinnae or ragged frond margins; moth larvae are the typical culprit in summer months
Control: Hand-pick caterpillars and egg masses from frond undersides; encourage birds; Bacillus thuringiensis (Bt) spray is effective applied early in the season when larvae are small
Keep oak fern pest-free
Healthy plants resist pests best. Get the basics right:
Oak Fern pests — FAQ
What is eating my oak fern?
Oak Fern (Gymnocarpium dryopteris) is a delicate woodland groundcover fern with very few pests. Slugs and snails may nibble the soft, triangular fronds, especially in spring. Caterpillars of certain moth species occasionally eat frond tissue. Its modest size means even light damage is visible, but the spreading rhizomes enable quick recovery.
How do I get rid of slugs and snails on oak fern?
Holes and notched frond edges on tender new growth; in damp woodland conditions slugs can cause patchy defoliation of young fronds Apply iron phosphate pellets or Phasmarhabditis nematodes in spring when fronds emerge; remove bark and stone debris where slugs shelter; avoid overhead watering in the evening
How do I get rid of caterpillars on oak fern?
Holes chewed from the centre of pinnae or ragged frond margins; moth larvae are the typical culprit in summer months Hand-pick caterpillars and egg masses from frond undersides; encourage birds; Bacillus thuringiensis (Bt) spray is effective applied early in the season when larvae are small