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.
Female lice live for up to 40 days, during which time they can lay more than. 100 eggs. They attach their eggs (known as nits) to hairs close to the scalp. surface. The eggs are yellow or white, and the size of a pin head. They take 7. to 10 days to hatch, and the new lice can then lay more eggs after about 7. days. The eggs that still contain unborn lice usually lie within half a centimetre. of the scalp surface. Empty egg cases remain firmly stuck to the hairs and.