AbstractThree legumes, red clover (Trifolium pratenseL.), alfalfa (Medicago sativaL.) and birdsfoot trefoil (Lotus corniculatusL.), were planted with a minimum‐tillage drill into eight grass fields, three in early spring, two in late spring and three in late summer, in Pennsylvania. The objective was to use pesticides at planting time to control slugs and insects which attack legume seedlings and ascertain whether pest control prevented seedling loss and increased yields of grass and legume dry matter (DM),in vitroDM digestibility and crude protein (CP). Methiocarb bait alone or in combination with carbofuran granules or spray applied at planting sometimes controlled the slugsDerocerus reticulatum(Müller),D. laeve(Müller) andArion fasciatusNilsson and improved establishment of seedling red clover and alfalfa but not birdsfoot trefoil. Increased yields of DM, digestible DM, CP and legume DM after treatment was greatest in late‐spring sowings. Larvae of the clover root curculio,Sitona hispidulus(F.), attacked roots of legumes in the spring following the year of sowing. Late spring and summer sowings without pesticides sustained considerable seedling losses from pests, whereas seedlings from early spring sowings in untreated areas were injured