22 INSECT LIFE IN POND AND STREAM 



insects manage to walk so easily on the top of 

 the water, and never "get wet or sink down 

 to the bottom of the pond ? 



It is because the surface of the water is al- 

 ways covered with a kind of elastic skin, called 

 the " surface-film." It is very, very thin, and 

 quite invisible, but it is strong enough to bear 

 the weight of many tiny creatures. As the 

 Pond- skaters run over the surface-film their 

 feet make little dents in it, but do not sink 

 through. If you watch the little insects 

 darting about on the top of a clear, shallow 

 pool when the sun is shining, you will see the 

 shadows of these tiny dents on the sandy 

 bottom of the pool. 



The Pond- skaters are rather timid little 

 things, and although they live on other small 

 insects they generally content themselves with 

 dead ones and seldom hunt for living prey. 

 When they are not skating about looking for 

 something to eat, these funny creatures are 

 generally very busy brushing their legs and 

 cleaning themselves up, for they are most 

 particular, tidy insects. Their heads, their 

 bodies, and even their long, thin legs are closely 

 covered with a short velvet pile, so even if 

 they venture beneath the surface-film, and 



