﻿10 BUEEETI'N 135&; U. S. DEPARTMENT OF AGRICULTURE 



tion of weevils present among the beetles was very large, as members 

 of this group were identified 27 times. Many were small forms 

 found on aquatic vegetation. Other groups of beetles are repre- 

 sented by scattering individuals picked up at random from the mud 

 or the scanty growths of grass in marshy lowlands. Many of these 

 miscellaneous beetles probably represent individuals which had 

 ■drifted in on the shore after having been drowned. A few are forms 

 found about decajdng bodies, objects encountered frequently on 

 borders of pools where the Wilson phalarope makes its home. JRove 

 beetles (Staphylinidse) and shining carrion-beetles (Histeridse) 

 belong especially in this class. 



Diptera. — Flies are one of the main sources of food supply for the 

 Wilson phalarope, constituting 43.1 per cent of the total. Mosquito 

 larvse which alone amounted to 5 per cent of the whole, constituted 

 ■one-tenth of the food in 27 stomachs collected in May; in 45 taken 

 in June they composed 2.5 per cent. These larvae v/ere taken also in 

 numbers in birds killed in August. That large numbers of larvae 

 were often consumed at a single meal was shown by the presence of 

 many of the breathing tubes through w^hich the wrigglers obtain air 

 when at the surface of the water. Crane flies (Tipulidse) were found 

 10 times, their larvae, which are aquatic, 8 times, and adults twice. 

 Gnats (Chironomidae) were more abundant in the food, being identi- 

 fied in 20 stomachs, the larvae and pupae in 10, and adult flies in a 

 like number. In the immature stages insects of this group live in 

 water, but the adults frequently swarm over marshes. To birds 

 secured in the Great Basin region alkali flies (Ephydridfe) were favor- 

 ite food. In all, members of this family were found 23 times, mostly 

 in the larval or pupal stages, when they are easily accessible. The 

 abundance of these insects in many localities is almost beyond ex- 

 pression in words, and they form a prime source of food in saline 

 situations where few other creatures can exist. Other aquatic fly 

 larvae that occur in fresh water were taken, among them a large 

 horsefly (Tahanus). 



Miscellaneous. —Sn&ils were found in tw^o stomachs taken in March, 

 but amounted to only 0.3 per cent of the diet for the whole period. 

 Other miscellaneous animal food came to 1.8 per cent, including a few 

 larvae of Mayfhes and in one case the immature form of a dragon- 

 fly. Caddisflies were found once and caterpillar remains once. 

 Ants were found twice, and remains of a few other hymenopterans, 

 but amounted to very little in bulk. Fragments of spiders were 

 found three times. The comparatively small number of miscel- 

 laneous forms is surprising considering the manner in which the birds 

 feed. 



VEGETABLE FOOD 



The vegetable food of the Wilson phalarope composed 6.7 per 

 ■cent of the total and was made up almost entirely of seeds of aquatic 

 plants or of plants that grow in marshy situations. Material that 

 may be called vegetable rubbish was encountered 5 times and con- 

 sisted of small particles that probably were obtained incidentally and 

 swallowed by the birds when in eager pursuit of active prey. Seeds 

 of pondweeds were found 6 times and of widgeon grass 5. Species 

 of rushes (Scirpus) were identified 19 times, other sedges 6, and seeds 

 of smartweed (Polygonum) 5 times. It will be noted at once that 

 most of these seeds have hard outer coverings, and it seems prob- 



