FOOD HABITS OF SHOAL-WATER DUCKS. 9 



beetles (Coleoptera), 0.04; dragonflies and damselflies and their 

 nymphs (Odonata), 0.01; and other insects, 0.03 per cent. 



One Oregon bird had made almost a full meal of adult caddisflies 

 in October, and the tube-shaped larval cases were found in the 

 stomachs of 8 others. 



The Diptera usually consisted of larvae or pupae, but occasion- 

 ally of adult flies. Six families were represented, as follows: Crane- 

 flies (Tipulidae), found in 1 stomach; midges (Chironomidae), in 

 10; soldierflies (Stratiomyidae), in 2; horseflies (Tabanidae), in 1; 

 Borboridae, in 3; and Ephydridae, in 8. 



The bugs taken were chiefly aquatic. Water boatmen (Corixidae) 

 had been eaten by 25 gadwalls, creeping water bugs . (Naucoridae) 

 by 6, and water striders (Gerridae) by 4, while shorebugs (Saldidae), 

 stink bugs (Pentatomidae), and plant hoppers (Fulgoridae) were 

 taken by 1 each. 



The most common Coleoptera were water scavenger beetles 

 (Hydrophilidae), predacious diving beetles (Dytiscidae), ground 

 beetles (Carabidae), leaf beetles (Chrysomelidae), and weevils 

 (Rhynchophora) . Other families represented were rove beetles 

 (Staphylinidae), larder beetles (Dermestidae) , ladybugs (Coccinel- 

 lidae), pill beetles (Byrrhidae), leaf chafers (Scarabaeidae), darkling 

 beetles (Tenebrionidae) , flower beetles (Anthicidae), and blister beetles 

 (Meloidae) . Of the 362 birds taken during the fall and winter months, 

 only 23 had eaten beetles, and these never amounted to more than 4 

 per cent of the stomach contents. Of 11 ducklings taken in July, 

 however, all but one had eaten beetles; in three instances these 

 amounted to 15 per cent, and constituted 7.09 per cent of the food 

 of all. 



Two gadwalls had eaten nymphs of dragonflies (Anisoptera) , two 

 those of damselflies (Zygoptera), and one an odonate nymph, too 

 badly ground to be identified. 



The miscellaneous insects consisted of a few ants, ichneumons, 

 etc. (Hymenoptera) , and a caterpillar (Lepidoptera) . Together they 

 amounted to only 0.03 per cent. 



CRUSTACEANS (CRUSTACEA), 0.08 PER CENT. 



Crustaceans evidently are not much sought after by the gadwall. 

 Twenty-one birds had eaten very small bivalved crustaceans (Ostra- 

 coda), usually in small numbers. Three gizzards contained the 

 fingers of crabs, two the remains of crawfish, and one a sowbug 

 (Oniscus asellus). Altogether, crustaceans furnished only 0.08 per 

 cent of the gadwall's food. 



MISCELLANEOUS ANIMAL FOOD, 0.08 PER CENT. 



The stomach of a gadwall from an open lake in northeastern 

 Arkansas contained several hundred of the small reproductive buds, 



