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 are live, so a person exposed can have live lice relatively fast if the encounter was sufficient. Head to head activities, use of combs/brushes, sharing hats, all can transmit lice from one person to the next almost immediately. Nits are either unhatched eggs or the remnants of hatched egges. Obviously, the unhatched eggs are problematic, since they will hatch in about two weeks and be mobile. Soon, they will be laying there own eggs. Nits are firmly glued to the hair shaft. The unhatched nits are within a 1/4 or so of the scalp. The nits do not easily transfer from person to person unless it is with combs or brushes.