14 BULLETIN 1359, TJ. S. DEPAKTMENT OF AGRICULTURE 
(Notonecta) were found 3 times and a form of water bug (Belostomat- 
idae) once. Water-boatmen, identified in 23 instances, seem to be 
standard article of diet. 
Coleoptera. — Beetles as a group constitute 11.4 per cent of the food. 
Among them small shore-haunting ground beetles were common, 
none known to be of economic importance. A few crawling water- 
beetles (Haliplidae) were found and a number of predacious diving 
beetles. Larvae of this latter group were identified 9 times. Water- 
scavenger beetles in both adult and larval stages also were well repre- 
sented. Weevils were as abundant as other groups of beetles and 
included billbugs (SpJienopJtorus) in 5 instances. 
Diptera. — Flies, amounting to 23.8 per cent of the total subsistence, 
compose the largest single item in the animal food. Although abun- 
dantly represented, the species taken belong to comparatively few 
groups. Larvae of crane flies (Tipulidae) were taken 4 times and larvae 
and pupae of flies that could not be certainly identified 5 times. The 
immature stages of gnats ( Chironomidae) were especially sought. 
Individuals identified as belonging to the typical genus Chironomus 
were found 6 times, and those of related forms, 11. Often many 
were found in one stomach, though ordinarily so broken that they 
could not be counted with accuracy. In a number of instances, how- 
ever, it was ascertained that several hundred had been swallowed by 
one bird. 
In the Great Basin region alkali flies (Ephydridae) were favored as 
food, as they were not only palatable but abundant about brackish 
or saline waters and in most cases easily secured. In spring and early 
summer thousands of these flies are found gathered in close array on 
expanses of soft, alkaline mud. Avocets run up hastily to such con- 
gregations and strike at them with lateral sweeping motions that fill 
their bills with them and with soft mud before the insects can escape. 
At such attacks the flies in limited areas rise in sudden swarms, but 
others at a short distance remain quiet, so that by taking a few steps 
the birds are able to make another attack on gatherings whose num- 
bers have been augmented by the arrival of individuals frightened up 
at the first onslaught. The larvae of these flies abound in many places, 
especially in the strongly saline waters of the lakes characteristic of 
the Great Basin. At Great Salt Lake many avocets after the nesting 
season frequent shallow bays near the lake front, where these larvae 
swarm, in order to feed upon them. 
Miscellaneous. — Snails are eaten occasionally by avocets and were 
found in 6 stomachs, although they amount only to 0.8 per cent of 
the total. The species are those common in shallow ponds and 
marshes. Other miscellaneous items of animal food, 14.5 per cent, 
include a varied assemblage of forms, none of which were present in 
sufficient number to merit separate tabulation. Nymphs of May- 
flies were found twice, and cases and other remains of caddisfly 
larvae 3 times. Caterpillars were identified 3 times, and fragments 
of small grasshoppers (Acridiidae), 4. The Hymenoptera were repre- 
sented by single findings of ants, a larrid, a braconid, and one other 
form not identified. Spiders were found in 2 instances. A small 
chub (Leuciscus lineatus) had been eaten by one bird and an unidenti- 
fied fish by another. Bones of a tiny salamander were encountered 
in the stomach of one bird. 
