The large pine weevil is the most serious pest of conifer reforestation in Ireland. The adult weevil causes damage by feeding on the bark of young transplants. With up to 100,000 adult weevils emerging per hectare on recently felled conifer sites, it is not uncommon for 100% of young plants to be killed. Pine weevils are susceptible to attack from a number of natural enemies such as fungi, parasites and predators. Of these, insect killing nematodes (microscopic worms) are the most promising biological control agent: capable of reducing weevil populations by up to 70%. The practicalities of using nematodes, their environmental safety and their potential for use as part of an integrated pest management strategy are discussed.