72 LOWER PTERYGOTA 



A common species in the northern states is Labia minor, 

 which occasionally may be seen flying in large numbers 

 around barnyards. It has not occasioned noticeable injury, 

 however, and is not counted of special economic importance. 



Order PLECOPTERA. 



This grou]) includes the stone flies, and the species are 

 all aquatic, but in general characters they are pretty closely 

 related to the Orthoptera. The mouth jjarts are mandibu- 

 late, the front wings are narrower than the hind wings, which 

 fold together and are co\ered by the front wings when at 

 rest. The transformations are incomplete, the larvse dis- 

 tinctly aquatic and provided with tracheal gills along the 

 side of the body, which permit them to absorb oxygen from 

 the water. The species have an importance as a source of 

 food supply for aquatic animals, and in some localities they 

 probably furnish a considerable support for certain kinds of 

 fishes. 



The adults are usually found in the vicinity of water, on 

 tree trunks or rocks, but except as they may attract atten- 

 tion they have no particular importance. Unlike the May 

 flies, they are not strongly attracted to light, and are seldom 

 noticed except in their native habitat. 



Order EPHEMERIDA. 



May flies form an order frequently placed as the lowest 

 of the winged insects. While showing some simple structure, 

 we may consider their simplicity due to reduction or speciali- 

 zation. The mouth parts of adults are reduced, fore wings 

 large, hind wings small. They are specialized in the aquatic 

 habit of the larval stage. The genera and species are not 

 particularly numerous. The name Ephemera was applied 

 on account of their very short apparent life. They are 

 developed from aquatic forms that have a period of develop- 

 ment of from one to three years, but have a very short life 

 in the adult stage. There are many species that come out 



