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.
The eggs hatch in about 8 or 9 days. The newly hatched louse (nymph) will suck blood for food and shed its skin (molt) three times as it develops into an adult over a 10-day period. The young lice and adults live their entire lives on the head, feeding on blood.