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.
Lice eggs hatch within 1 to 2 weeks after they're laid. Adult lice and nymphs (baby lice). The adult louse is no bigger than a sesame seed and is brownish tan (although lice may look darker on people with dark hair). Nymphs are smaller and become adult lice about 7 days after they hatch.Most lice feed on blood about every 4 to 6 hours, but they can survive up to 3 days off the scalp.Medicated lice treatments can usually kill the lice and nits, but it may take a few days for the itching to stop.ymphs are smaller and become adult lice about 7 days after they hatch. Most lice feed on blood about every 4 to 6 hours, but they can survive up to 3 days off the scalp.Medicated lice treatments can usually kill the lice and nits, but it may take a few days for the itching to stop.