Insects and the germs they carry
Flies and cockroaches have more germs on them than the ants or beetles.
Insects and diseases
Most insects carry bacteria, viruses and parasites on their bodies. When these insects come into contact with people or when they bite/sting, they leave behind many types of germs. Some of these germs cause diseases. Insects like mosquitoes, some species of flies, beetles and fleas spread diseases when they suck on the blood of a diseased person and then bite or feed on a healthy person.
Very few diseases are actually caused by the bite of the insects. More often than not, it is the disease causing microorganisms or pathogens that are passed on to people when they are bitten by the insects that carry these diseases.
Houseflies are known to carry millions of microorganisms on their feet. They pick up microorganisms when they sit on feces. These microorganisms are passed to a person when he consumes food and drinks that the house flies contaminate. This is how people contract typhoid and cholera. Cockroaches are also known to thrive in filthy environments and are very capable of spreading diseases. Mosquitoes are known to cause dengue fever and malaria. The Tsetse fly carries a type of protozoa that is known to cause "sleeping sickness".
Always follow laboratory safety guidelines and always practice sterile technique when handling microbes. Never have any food or drink at your workstation and always thoroughly wash your hands with disinfectant soap or alcohol before leaving your workstation. Always dispose of used material in a biohazard bag. If none are available, the bacteria should be destroyed with bleach before being disposed of. Knives should be handled under adult supervision.