All Trichostrongylus species have a direct life cycle, i.e. there are no intermediate hosts involved. Adult females lay eggs in the large intestine of the host that are shed with the feces. Once in the environment the eggs release the L1-larvae that complete development to infective L3-larvae in about 5 days by suitable weather (hot and humid), significantly longer by cold weather. These infective larvae can survive in the environment and remain infective for up to 6 months.
Livestock becomes infected after ingesting such larvae while grazing or with contaminated soil. After ingestion, larvae of Trichostrongylus axei complete development to adult worms in the stomach, where they may penetrate into the lining of the abomasum. Larvae of other species reach the small intestine, where they get into the crypts of the lining and complete development to adults.
The prepatent period (time between infection and first eggs shed) is 3 to 4 weeks, depending of the species and the host.