EPHEMERIDA 



127 



tries or under leaves, and in the spring they are sometimes 

 found in large numbers on the surface of pools of water or upon 

 the snow. 



^ Campo'dea staphyli'nus, which is regarded as the most primitive living 

 msect, belongs to this order. It is about I inch long, white, wingless, 

 and flat. Its body is exceedingly 

 soft and delicate. It is widely dis- T" 

 tributed. 



The "fish-moth" (Lepis'ma sac- 

 chari'na) of the house (Fig. 98), which 

 is neither a moth nor a fish, is sil- 

 very white, with a yellowish tinge 

 on antennse and legs. It is about ^ 

 inch long, has three long caudal ap- 

 pendages, and feeds chiefly upon 

 sweet starchy materials, often at- 

 tacking starched clothing and the 

 paste of wall-paper and book-bind- 

 ings. It may be gotten rid of by 

 sprinkling fresh pyrethrum powder 

 in the places infested or by spraying 

 shghtly with nicotin or formalin. 



The "spring-tails" {CoUem'bola) 

 have a forked spring attached to the 

 next to the last segment of the ab- 

 domen, by means of which they leap 

 from a few inches to a foot in the air. 

 The " snow-fleas " collect in large 

 numbers on the snow in spring. 

 They are often a cause of great an- 

 noyance where maple sugar is made. 



Surely the insects of this Fig. 98. — Lepis'ma sacchaH'na, 



order, by their simphcity of g^^^rotAir^cuVtur^r^'' ^^ '' 

 structure and their similarity 



of somites, show their worm ancestry, though some species 

 show much more complexity of structure. It will be interest- 

 ing for the student to consider how, from such a generalized 

 primitive form as Campodea staphylinus, nature can produce, 

 by modification of parts, an insect of highly complex structure. 



ORDER II. EPHEMER'IDA 



The May-flies, in the adult form, are insects of a day, but 

 they pass two or three years in the larval stage. When they 

 emerge from their larval condition into their winged form 



