Thus a pair of brown rats can produce as many as 2,000 descendants in a year if left to breed unchecked. (A rat matures sexually at age three to four months.) An average rat's life span is two to three years.5 A rat can tread water for three days and survive being flushed down the toilet.hus a pair of brown rats can produce as many as 2,000 descendants in a year if left to breed unchecked. (A rat matures sexually at age three to four months.) An average rat's life span is two to three years.
Late lice. The common head louse, Pediculus humanus capitis, may take as long as 14 days to hatch. Gilles San Martin/Wikimedia Commons. Hereâs some lousy news for parents of itchy-headed kids: Lice eggs can take 2 weeks to hatch in human hair, making standard 7-day delousing treatments ineffective in some cases.
Nits are the small, oval-shaped eggs of head lice. Lice lay their eggs very close to the scalp, and the eggs hatch within a week. Nits may be tan or coffee-colored. They are hard to see until they hatch.its are the small, oval-shaped eggs of head lice. Lice lay their eggs very close to the scalp, and the eggs hatch within a week. Nits may be tan or coffee-colored. They are hard to see until they hatch.