﻿FOOD HABITS OF THE VIREOS 17 



in size between the pentatomids and the smaller leaf-feeding bugs, 

 the actual number of leaf hoppers and other small bugs is probably 

 as great as that of the stink-bugs or even greater. 



Coleoptera. — Beetles of all kinds, making up 12.9 per cent of the 

 yearly food, stand third in the diet. Ladybird beetles, usually 

 plentifully found in the stomachs of vireos, in this species amount to" 

 less than 1 per cent of the total. The rest of the insects may be classed 

 as injurious, or potentially so. The weevils, or snoutbeetles, make 

 4.23 per cent, or about one-third of all the coleopterans eaten. The 

 wood-boring forms belonging to the families Buprestidae and Ceram- 

 bycidae and the plant-feeding Elateridae, together form more than 

 one-fourth of the beetle food, or 3.57 per cent. Dung beetles and 

 leaf chafers (Scarabaeidae) amount to 1.84 per cent, whereas leaf 

 beetles (Chrysomelidae) and ladybird beetles ( Coccinellidae) make, 

 respectively, 0.82 and 0.62 per cent of the yearly food. Fragments 

 of beetles that could not be associated with any of the above-men- 

 tioned families together make up 1.82 per cent of the whole. 



Diptera. — Two-winged, or true, flies, make up 7.36 per cent of the 

 yearly subsistence, of which the major part is consumed in May and 

 June. More than one-fourth of the stomachs of the yellow-throat 

 examined contained remains of flies, although in most cases the 

 insects were not in condition to permit more specific identification. 

 Midges (Chironomidae) and horseflies (Tahanus) were among the 

 dipterans eaten. 



Hymenoptera.- — No honeybees were identified in the 160 stomachs 

 of the yellow-throated viero examined, but other bees, as Andrena 

 or Halictus, were found. Sawfiies and ichneumon flies also were 

 determined. Other hymenopterans were detected in lesser quantity, 

 and together the insects of this order made up 5.07 per cent of the 

 annual food. 



Other insects.- — ^The rest of the insect food amounts to 4.92 per cent, 

 about equivalent to the bulk hymenopterans taken. Under this head 

 are gathered all records of grasshoppers, crickets, locusts, and dragon 

 flies and other water-inhabiting forms. In the food of the yellow- 

 throated vireo this group is not of very great importance economically. 



Other animal food. — Spiders, with the few snails the bird happened 

 on, made up 2.38 per cent of the food. Snails were taken during 

 April only and then only to the extent of 0.36 per cent, which, trans- 

 lated into a yearly percentage, makes the insignificant total of 0.06. 

 Among the spiders eaten, the Attidae, or jumping spiders, were the 

 most common. Species of Phidippus were determined four times, 

 and fragments referable to family only were found in six other stom- 

 achs. The tetragnathids, which infest marshy localities, were iden- 

 tified twice, and once a minute psoudoscorpion of the genus Chthonius 

 was detected. In general, the spiders eaten are only slightly beneficial. 



VEGETABLE FOOD 



The yellow- throated vireo eats comparatively little vegetable food, 



f)ractically none during April and May, none during June and July, 

 ess than 2 per cent in August, and less than 9 per cent in September. 

 The average for tlie year is only 1.74 per cent. Among the items 

 specifically determined were sassafras borri(^s and seeds of wild grapes. 

 No cultivated fruit of any kind was found. 



50209— 25t 3 



