Cockroaches - just like humans - become frail in their old age, a new scientific study has revealed.
Old cockroaches often trip over themselves, the study says
US researchers found that the joints of elderly cockroaches seize up so that they have trouble crawling up slopes.
Many insects which survive into old age, some 60 weeks, develop a stumbling gait and, later, trip over themselves.
"It happens every couple of steps," Angela Ridgel, who led the study at Case Western Reserve University, told New Scientist magazine.
"It does slow them down," she added.
By 65 weeks, more than 80% of the insects were tripping over themselves, the study said.
The researchers found that ageing cockroaches reduce the time they spend moving around by about 40%.
They also said that old cockroaches performed badly at climbing a 45-degree slope, with nearly 60% failing to get over the top.