wide and from 1 to 2 inches deep. The sides slant sharply from 
the rim to a point in the bottom. The adults have long slender 
bodies and two pairs of long, narrow, delicate, many-veined 
wings; larvae are broad, somewhat flat, taper toward each end, 
and have long, curved mandibles armed with strong spines and 
setae. The larva lies hidden under sand at the bottom of its pit 
and feeds on ants or other insects that fall into the pit. 
Order EPHEMEROPTERA 
Mayflies 
Mayflies are frail, delicate insects, with medium-sized, soft 
bodies that end in three long threadlike tails, or caudal setae. The 
wings are membranous and many-veined and are held upright 
while at rest. The front pair are large and triangular; the hind 
pair, when present, are small and rounded. The antennae are 
bristle-like and inconspicuous; the mouth parts vestigial. The 
nymphs are elongate and cylindrical or flattened, and have leaf- 
like gills along the sides of the body. In most species the gills 
have three long tails. 
Mayfly nymphs live under stones or among debris on the bottom 
of streams, where they feed on decaying vegetable matter, algae, 
and diatoms. When they become full-grown they leave the water 
and transform to adults on nearby vegetation. The adults occa- 
sionally appear in enormous numbers, but they seldom live longer 
than a day or two. Occasionally, their dead bodies literally pile 
up along the shore, on bridges, or in the streets of nearby towns 
(560). 
Beyond the occasional nuisance effect created by the presence 
of piles of dead insects in areas frequented by man and the impor- 
tance of the nymphs as fish food, which is substantial, mayflies 
are of no economic importance. | 
Order PLECOPTERA 
Stoneflies 
Stoneflies are small to medium-sized, drab-colored insects, with 
soft, flattened bodies. The wings are membranous and have nu- 
merous cross veins. The front pair is rather narrow and elongate; 
the hind pair is shorter but wider and is usually folded in pleats 
while at rest. The antennae are long, slender, tapering, and many- 
segmented. The cerci, when present, are usually long and many- 
jointed. The nymphs are flat-bodied and somewhat elongate. They 
have long antennae, long cerci, and branched gills on the thorax 
and about the bases of the legs. 
Stonefly adults occur near streams or along rocky shores of 
lakes. The nymphs are aquatic and are usually found under stones 
in the rapids of streams. When they reach maturity, they leave 
the water and climb up on nearby objects to transform to the 
adult stage (558). 
Stoneflies may be a nuisance at times, especially when they ap- 
pear in swarms in recreational areas. The nymphs are an impor- 
tant source of fish food. 
44 
