CHAPTER IV 



THE SIMPLEST INSECTS (Order Aptera) 



ERTAIN household pests which are 

 not moths and do not look like 

 fish, but which are com ^^^| monly called "tish-moths" (Fig. 86), are 

 our most familiar repre sentatives of the order of "simplest in- 



sects." The "fish" part of the name comes from the 

 covering of minute scales which gives the body a silvery 

 appearance, and the "moth" part is derived from our 

 habit of calling most household insect pests "moths." 

 Thus we speak of " bufTalo-moths " when we refer to the 

 carpet-feeding hairy larva; of certain beetles. When we 

 say clothes-moths we are really using the word moth 

 accurately, for in their adult condition these pests are 

 true moths, although the injury to clothing is wholly done 

 by the moth in its young or caterpillar stage. 



Besides the fish-moths other not unfamiliar Aptera are 

 the tiny "springtails" (Fig. 87), which sometimes occur 

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

 snow in the spring. Others may be easily found in damp 

 decaying vegetable matter, as discarded straw or old toadstools. They are 

 provided with an odd little spring on the under side of the body by means 

 of which they can leap from a few- inches to a foot 

 or more into the air. Hence their common name. 



In the order Aptera are included the simplest of 

 living insects. By ".simplest" is meant most primi- 

 tive, most nearly related to the ancestors of the whole 

 insect class. Also, as might be expected, these most 

 primitive insects are simplest in point of bodily struc- 

 ture; but in this respect they are nearly ap|)roached 

 by .simple-bodied members of several other orders. 

 These latter forms, however, have a simple body- 

 structure due to the degradation or degeneration of a more complex t_\T)e. 



58 



Fig. 86.— The fish- 

 in o t h , Lepisma 

 saccharina. (.^^fter 

 Howard and Mar- 

 latt: twice natural 

 size.) 



Fig. 87. — The pond-sur- 

 face springtail, Smyn- 

 Ihtirus a q ita t ic u s . 

 (After Schott; much 

 enlarged.) 



