What are fly spots or the marks on walls due to flies?

Each female fly is capable of laying up to

2000 eggs many of which may reach adult life with in twelve days.

These new young flies are then ready to start the cycle all over

again.

WHY FLIES ARE DANGEROUS

Flies do not only carry germs on their feet

and legs, but also inside their bodies. Every fly has a sort of

pouch or reservoir which it fills when it eats. After taking a full

meal at some filthy rubbish dump, the fly wings its way to some

more comfortable spot where it can rest and digest its meal. There

the fly transfers this filthy material from the pouch to its own

stomach often leaving parts of the meal behind. This is what causes

fly spots on walls and ceilings, and perhaps even on your own food

if you are careless enough to allow flies inside your house.