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 “ fish-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 “buffalo-moths” when we refer to the 
carpet-feeding hairy larvae 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 approached 
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 type. 
58 
Fig. 86. —The fish- 
moth, Lepisma 
saccharina. (After 
Howard and Mar- 
latt; twice natural 
size.) 
Fig. 87. —The pond-sur¬ 
face springtail, Smyn- 
thurus aquations. 
(After Schott; much 
enlarged.) 
