| 环境 |
cockroach; cockroaches; cockroach The most primitive of the living winged insects. It is thought they have been unchanged for more than 300 million years, and are among the oldest fossil insects. Cockroaches are usually found in tropical climates, but a few species, out of the total 3.500 known species, have become pests. They are common household pests in many countries, imported by ship and carried home in grocery bags. Cockroaches eat plant and animal products, including food, paper, clothing and soiled hospital waste, fouling everything they touch with their droppings and unpleasant odour, to which many people are allergic. They are a major health hazard and carry harmful bacteria, protozoan parasites and faunal pathogens, including those that cause typhoid, leprosy and salmonella. Conventional insecticides make little or no impact on the cockroaches population |
