HABITS AND STRUCTURE OF INSECTS. 103 



great lakes it is a common sight to see the gas-posts and 

 adjoining buildings blackened by the myriads of Ephemera 

 which have been blown in from the lakes and have been at- 

 tracted by the lights. The following figure represents a 

 gas-post, in Cleveland, Ohio, as it appeared with Ephemera 

 clinging to it : 



FIG. 99. GAS-POST, WITH EPHEMEKA CLINGING TO rr. 



95. Another group of insects somewhat resembling the 

 Ephemera pass their larval state in the water. 



Some of their larvae are called caddis-worms, or case- 



