312 DRAGONFLIES OF NORTH AMERICA 
Gomphus with its 45 species. In the suborder of the Zygoptera it is 
dominant, both in the number of described species and the number of 
individuals. In all faunal lists of Odonata, the term “common” appears 
frequently after the names of the species. 
While Enallagmas frequent all types of aquatic habitat, being re- 
corded even from brackish water and desert alkaline pools, they prefer 
still, shallow, fresh water, where there is an abundance of submerged 
and floating vegetation. 
The adults spend most of their time over the surface of the water, 
or in the grasses along the shores of the lakes and streams, but oc- 
casionally they are found in the woods and fields. They fly from plant 
to plant, or from one mass of floating algae to another, they are particu- 
larly fond of resting on bulrushes and cat-tails, or on floating lily pads. 
They fly very low, some species so low that it is well nigh impossible to 
get a collecting net under them without dipping the water. In foraging 
they fly through the vegetation, seldom over it, and do not often de- 
part very far from the borders of the water. They flit easily about 
among the grass stems and settle often in a rigidly horizontal position 
on the stems and leaves. Their food consists mainly of small Diptera, 
mosquitoes, midges, etc., that swarm in such places. They are eaten 
by frogs, which lie in ambush amid the floating algae, and catch them 
when they come to mate or oviposit; by swallows and other birds, that 
can fly close enough to the water to get them. They are snared in 
spiders webs, and are captured and eaten by robber-flies, dragonflies 
and other damselflies. 
The eggs are deposited in punctures in the tissues of green plants 
just beneath the surface of the water. Floating leaves are preferred, 
but the stems of standing aquatics are often found thickly punctured 
and filled with eggs in all stages of development. Oviposition gener- 
ally is performed in copulo, the male flying along with the female. 
They do not, as a rule, descend below the surface; however, several 
species have been observed to do so, in which case the female is un- 
accompanied by the male. 
The adults divide sharply into two groups on color, the larger group, 
being bright blue and black, the other, black with yellow or orange 
markings. The head is predominantly black above, with the mouth 
parts, the anteclypeus, the genae, the postgenae and the occiput, pale. 
The postclypeus (nasus) is usually black, but in some if species is pale 
with reduced black markings. There is a pale transverse frontal band, 
just above the clypeus, on the frons, of varying width, sometimes ex- 
tending as far as the median ocellus. The vertex is usually entirely 
