Shot of two men removing box from Noorduyn Norseman seaplane on Northern Lake. TRAVELLING SHOT of water during take-off, AERIAL SHOTs of spruce forests, lake, islands as plane gains altitude. AERIAL SHOT over dense evergreen forest along edge of lake, over forest. AERIAL SHOT over several buildings in clearing along lake shore. MS of water during take-off, of water as plane gains altitude. AERIAL SHOT over evergreen forest, rivers, lakes. CUs of spruce bud worm crawling along branch, nibbling at needles. CUs of spruce bud larva in cocoon stage, larvae spinning on spruce needle, larvae emerging from cocoon. Shot of sign "Department of Agriculture Canada - Entomological Branch - Parasite Investigations". TILT DOWN from tree tops to LS of stone building housing offices of parasite investigation branch of Department of Agriculture Canada. Shot of white coated entomologist studying bud worm through microscope. CUs of phytoditus fly on white background, on spruce needles. Sequence on entomologists studying specimens in laboratory. MCS of spruce tree covered with worms. MLS of spruce bud worm crawling along needles of blue spruce. AERIAL SHOT over freight yard, roundtable, buildings in small town, seaplane anchored to shore. ECUs of cocoon, empty chrysalis, spruce bud worm, phytoditus fly on worm.