40 



BIRDS OF A MARYLAI^D FARM. 



collected had taken these species. Others, such as Vespa, PoUstes, 

 Pomioilus^ Pelojxeus^ 2fonobia^ and AmmojMla^ were collectively 

 abundant on frequent occasions, but so far as observation went no 

 birds pre3^ed on them. 



That birds feed extensively on parasitic wasps is indisputable; but 

 the harm thus done is less than might be supposed, for the usefulness 

 of such wasps is in inverse ratio to their size, and birds seldom select 

 the smallest forms, such as Braconid^e and Chalcididas. Mnetj^-seven 

 of the Marshall Hall birds, representing the following 36 species, had 

 eaten parasitic H^^menoptera. 



List of birds examined whose stomachs contained parasitic •zt'a^j;s. 



Bobwhite 



Downy woodpecker 



.Chimney swift. 



Kingbird. 



Great crested flycatcher 



Phoebe. 



Wood pewee. 



Blue jay. 



Bobolink. 



Red-winged blackbird. 



Meadowlark. 



Orchard oriole. 



Baltimore oriole. 

 Grasshopper sparrow. 

 Chipping sparrow. 

 Field sparrow. 

 Song sparrow. 

 Scarlet tanager. 

 Summer tanager. 

 Purple martin. 

 Barn swallow. 

 White-bellied swallow, 

 Bank swallow. 

 Eed-eved vireo. 



"Warbling vireo. 



White-eyed vireo. 



Yellow warbler. 



Magnolia warbler. 



Black-poll warbler. 



Louisiana water-thrush. 



Maryland yellow-throat. 



Chat. 



Redstart. 



Catbird. 



Long-billed marsh wren. 



Olive-backed thrush. 



In this mischief the flycatchers are Dy all means the greatest 

 offenders, the swallows next, and, less generalh^ but still noticeabty, 

 the warblers next. Of all the fl^^catchers the wood pewee appeared 



to be the most active and per- 

 sistent in this destruction. 

 Parasitic wasps are not usu- 

 alh^ so alert and swift as 

 man}" other insects; there- 

 fore they are easy victims. 

 Most of the class are ichneu- 

 mon flies (Ichneumonida3 — 

 fig. 13). Somewhat more 

 than a fifth of the birds that 

 had taken parasitic wasps, 

 however, had fed on a cer- 

 tain black wasp. Tip Ma inor- 

 nata^ which is a vigorous 

 eneni}" of the larva of the 

 Ma^^-beetle. These wasps 

 are so common in Maj^ and June that it is not unnatural that a 

 good many should fall prey to birds. The only other noticeably 

 abundant parasitic Hymenoptera were some very large braconids 



Fig. 13.— Ichneumon fly (after Howard; loaned by 

 Division of Entomology). 



