吸血的昆虫——牛虻、蚊类、螺类、白蛉子和螯蝇,一般大家叫牠們为可厌的小动物。在苏联极大地域內,牠們常給人与动物带来极大的危害。牠們中多数是傳染病的傳递者。无疑的,对这些小动物的生态学的研究与拟訂有效的防卫方法,是值得大大注意的。學校不能对这个問題置之事外。 學生熟悉这些小动物的生态學,是有助于專門研究的。观察前,教师首先应当熟悉牠們中分布較广的 Blood-sucking insects - bullfrogs, mosquitoes, snails, white slugs and flies, are generally called annoying animals. In the vast territory of the Soviet Union, they often bring great harm to humans and animals. Most of them are communicators of infectious diseases. Undoubtedly, great attention should be paid to the ecology of these small animals and to the formulation of effective defensive measures. The school can not set aside this issue. Students familiar with the ecology of these small animals will be useful for specialized research. Before observing, teachers should first of all be familiar with them widely distributed