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.
Thankfully, lice are not effective jumpers. In most cases direct contact is needed -- unlike many other infestations. But it could be direct contact with hair, a brush, a car seat, a stuffed animal, or the sofa. Usually the couple of lice that cause the infestations don't cause many symptoms themselves, but they begin to lay eggs -- day! Each crop of eggs hatches about six to 10 days later. Some people can have lice for months before they start to itch, because the itching is an allergic reaction to the lice stool.