AQUATIC INSECTS 



tail-piece which the springtail can fold beneath its body and 

 lock into two little appendages on the under side of the third 

 abdominal segment (Fig. 146). When it forces its tail-piece 

 suddenly downward, the springtail is lifted high in the air 

 as a kangaroo might be if it sat on its tail and snapped it hard 

 against the ground. 



Fig. 146. — Water springtail, Podura aquatica. 



Water springtail, Podura aquatica. — This common spring- 

 tail of slow streams and pools is dull bluish black and although 

 only one-fifth to one-fourth of an inch long the segments of 

 its body show very distinctly through a simple lens (Fig. 

 146). These springtails are exceedingly gregarious and 

 gather in enormous numbers, m.aking a blue-black band along 

 the margin of the water. The body surface is difficult to wet 

 because of the hairs which hold a blanket of air around it. 

 Springtails probably go to the bottom and hibernate there 

 through the winter since they are among the earliest spring 

 arrivals at the surface. They are said to live upon plant 

 tissues, but their food habits need more study. In Miall's 

 " Aquaticlnsects " there is a quotation from an account by 

 the entomologist De Geer, published in 1778. De Geer kept 

 springtails for a long time in a dish of water and found that 

 they crawled down to the bottom and lived there several 

 days at a time. It has been suggested that springtails may 

 climb down into the water and forage upon submerged plants. 



Occurrence. — In still water, along the margins of ponds 

 and streams. Common and generally distributed through 

 eastern and central North America. Common October- 

 November. 



191 



