Once outside the host, depending on the temperature, they can hatch within 24 to 48 hours. The eggs are relatively thin walled and require warm moist shaded conditions for embryonation. The eggs are susceptible to killing by frost or dehydration but also require oxygen for hatching and development thus they require light loamy soils. The released rhabdiform L1 larvae requires 2-3 days before it molts to the L2 stage and the second molt occurs after a further 5 days, producing the ensheathed infective third stage larva. The L3 are non-feeding active stages which move to the periphery of the faecal mass or into the soil, where they can remain active and infective for up to three weeks, depending on the climatic conditions.
Hookworms require a moist, fairly cool environment to survive and develop as free-living organisms.
The larval food reserves are stored in the form of unbound neutral lipid, and their rate of utilization may be the limiting factor which determines the duration of larval infectivity. When conditions are moist and humid, the larvae migrate to the top of the soil or faecal mass and undergo a behaviour known as nictating . During this process the worm almost stands on its tail and waves its head around, which presumable increases their chance of contacting the host. The larvae effectively exsheath at this point, the sheath still acts as an extra layer of protection against desiccation, and the worms can retract into it in between period of nictating. However, once a host is contacted, the larvae leave the sheath behind.