450 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



band across the jugulum; the tail feathers have large subterminal 

 white spots, the outer pair broadly rounded at the tips and reaching 

 less than an inch beyond the central pair. This plumage is worn 

 until after the birds leave for the south. Apparently a complete 

 jnolt takes place while the birds are in the south, probably beginning 

 with the body plumage in the fall and completed with the molt of 

 the flight feathers late in winter or early in spring; but we do not 

 know much about how this takes place, for adequate material is 

 lacking. We do know that the birds return in spring in a plumage 

 that is practically adult, with the long, attenuated lateral tail feath- 

 ers extending fully one and one-quarter inches beyond the middle 

 pair, with the metallic purplish feathers of the jugular band, the 

 chestnut throat, and the darker cinnamon abdomen. All these colors 

 are more or less variable, even in adults, where the sexes are often 

 very much alike, though the female is usually much paler than the 

 male. Adults have one complete annual molt, the postnuptial, after 

 they leave for the south; this is probably accomplished somewhat 

 earlier than that of the young. 



The barn swallow has been known to hybridize with the cliff swal- 

 low, as explained under that species. 



Food. — Professor Beal (1918) analyzed 467 stomachs of the barn 

 swallow and found that the food was made up of 99.82 percent animal 

 matter and 0.18 percent vegetable. "Diptera are evidently the choice 

 food of the barn swallow. They average 39.49 percent of the food, 

 or more than twice that of any order of insect." They are mostly 

 allied to the common house fly, but include long-legged crane flies 

 (Tipulidae), horse flies (Tabanidae) and several robber flies (Asil- 

 idae), which are said to be very destructive to honeybees. 



Beetles of various families amount to 15.63 percent. The useful 

 beetles, those that prey upon other insects, predaceous ground beetles 

 (Carabidae) and ladybirds (Coccinellidae), amount to only 3.4 per- 

 cent. All the remainder of the 80 species of beetles are "most of 

 them harmful and some exceedingly so." These include the May- 

 beetle family (Scarabaeidae), mostly small dung beetles, various 

 weevils, including the cotton boll weevil and the rice weevil, and 

 the "destructive engraver beetles that do so much damage to timber." 



Hymenoptera other than ants make up 12.82 percent, consisting of 

 bees and wasps, but only one honeybee was found, a drone. "Ants 

 are eaten by the barn swallow to the extent of 9.89 percent of the 

 food, some stomachs being entirely filled with wingless species." 

 Hemiptera formed 15.1 percent, including stink bugs, leaf bugs, plant 

 lice, and chinch bugs. Other items include a few Lepidoptera, 2.39 

 percent, mostly adults, still fewer grasshoppers and crickets, 0.51 

 percent; dragon flies, 4 percent; and a few May flies, spiders, and 

 snails. 



