THE BroLtocy or ErpHypRA SUBOPACA LOEW 603 
Secondly, the structure is a protective feature. The thick chorion of 
the egg, the thick hypodermis of the larva, and especially the hard skin 
of the pupa, enable the species to survive in a wide range of salinity and 
under various unfavorable conditions, and protect the insects from being 
harmed by mechanical means. 
Thirdly, the habitat seems to be protective in character. As already 
mentioned, eggs laid on the water surface sink to the bottom, and thus 
are avoided certain catastrophes that might be caused by temperature, 
climate, or mechanical agents. Furthermore, eggs are laid singly. Being 
so minute in size, they are by no means easy to detect by any predacious 
insect in the pools. The larva has a hiding or shelter-seeking habit. 
The perching habit of the mature larva has made the animal most incon- 
spicuous in its environment, and this is true also with the adult’s habit 
of resting on water surface or on mud where the scums afford a harmonizing 
background. 
Fourthly, the adaptability of the species to such a unique habitat is 
in itself protective. The salinity and density of the water unfit these pools 
as a habitat for most of the aquatic insects that thrive in fresh water. 
This keeps this species from contact with certain predacious forms. 
ENEMIES 
Since this species is so well protected, it is largely free from attacks 
by insects. In early morning, the writer has often seen flocks of sparrows 
feeding on the ground near the pools, but never did they attempt to feed 
on the larvae which were so numerous in the mud and shallow water. 
Herring gulls and kingfishers were seen several times flying over this 
region from the lake, and the latter often stopped somewhere near the 
pools, but never has the writer been able to see them feeding on the 
immature stages of the fly. Domestic fowls, on the other hand, are enemies 
of this species. Throughout the season fowls’ footprints were often found 
on the mud in the overflowed areas, and several times the fowls while 
hunting for food were seen to pick up larvae or pupae. Among insects, 
the only enemy observed was one of the common water striders, Gerris 
marginatus. Once a fly was noticed turned upside down on the water 
surface; before it regained its natural position it was caught by a water 
strider. The strider carried the fly around on the surface for about a 
quarter of an hour, but finally it disappeared in the grasses along the shore. 
