26 BULLETIN 862, IT. S. DEPARTMENT OF AGRICULTURE. 



MISCELLANEOUS VEGETABLE FOOD, 11.95 PER CENT. 



A largo number of minor items of vegetable food were classified as 

 miscellaneous. Probabty the largest of these consisted of plants of 

 the duckweed f amily . (Lemnaceae) . Although found in only 14 

 stomachs, they constituted nearly 100 per cent of the contents of 

 several. Each of three stomachs collected in Iowa in August con- 

 tained more than a thousand of the small plants of a duckweed 

 (Lemna sp.). Twenty-eight other families of plants were represented, 

 the most important being the aster family (Compositae), the water 

 plantain family (Alismaceae), the parsley family (Umbellif erae) , 

 crowfoot family (Ranunculaceae), borage family (Boraginaceae), 

 myrtle family (Myricaceae) , rose family (Rosaceae), horn wort family 

 (Ceratophyllaceae), and the vervain family (Verbenaceae) . 



Animal Food. 



Animal matter constitutes 29.47 per cent of the total food of the 

 blue-winged teal, which is more than three times the percentage of 

 animal food eaten by the green-wing. Over half of this (16.82 per 

 cent) is mollusks, the remainder being made up of insects, 10.41 per 

 cent; crustaceans, 1.93, and miscellaneous, 0.31 per cent. 



MOLLUSKS (mOLLUSCA), 16.82 PER CENT. 



The greater part of the shellfish found in the stomachs examined 

 probably consisted of snails, although small bivalves also had been 

 commonly taken, and in a majority of cases the shells had been so 

 thoroughly crushed by the powerful gizzards of the ducks as to 

 make it impracticable to distinguish between the fragments of 

 bivalves and univalves. However, 15 species of the latter were 

 identified, and 2 of the former. Unidentified univalve shells were 

 found in 31 stomachs and unidentified bivalves in 2, while fragments 

 of mollusk shells taken from 106 stomachs were not classified. The 

 full stomach of a duck collected in an Iowa swamp in August, 1907, 

 contained thousands of snail eggs, amounting to 54 per cent of its 

 contents. 



INSECTS (iNSECTA), 10.41 PER CENT. 



The items of insect food of the blue-winged teal, in the order of 

 their importance, are caddis larvae (together with their cases), 

 beetles and their larvae, dragonflies and damselflies (chiefly in the 

 nymph stage), bugs, flies (chiefly larvae), and a small percentage of 

 miscellaneous insects. 



The larvae of caddisfLies (Phryganoidea) or their cases were found in 

 37 stomachs, and amounted to 4.5 per cent of the total food. The 

 greater part of these were found in a series of stomachs collected in 

 Florida, some of which were over half filled with the fragments of 

 caddis cases. 



