Mature adults in lungs Eggs coughed up,swallowed. leave in the feces. Carried to right Eggs50×40 heart and lungs. Molts from L3-L4 microns and L4-L5 occur during this migration. Life Cycle of Metastrongylus spp. Earthworm ingests egg L3 penetrate small intestine,enter lymph Egg hatches L1 migrate to heart of worm Molts twice to L3 stage. Earthworm ingested by pig