86 BULLETIN 326, U. S. DEPARTMENT OP AGRICULTURE. 



outer edge of small shelves or holes and behind this is placed a felted mass of 

 plant downs from cactus and other plants to receive the eggs. From fragments 

 of shells examined the eggs appear to agree closely with those of P. lunifrons, 

 being white, spotted with reddish brown and lilac. North of Aguadilla about 

 40 pairs were nesting in small caves in cliffs over the ocean, some only 20 feet 

 above the waves. All nests were back in holes, and the birds circled about call- 

 ing excitedly in a close flock before the entrance, flying up two or three at a 

 time to hover before them for an instant. There must be a great mortality 

 here among the young, as there is no place for them to go on leaving the nest 

 except out over the waves, and it was some distance to safety at the top of the 

 cliffs. East of Lares in "La Cueva Pajita," a grotto 200 feet long and open at 

 both ends, was a colony of about 300 of these swallows, some of them near the 

 entrance, while others had built in so far that in the obscurity the birds could 

 not be distinguished from the large bats that circled about with them. Some 

 of the ledges supporting nests were so narrow that the sitting bird was forced 

 against the wall, greatly abrading the breast feathers. As these abrasions occur 

 only on one side, the bird must always have faced the same way while on the 

 nest ; both males and females incubate, as these were observed in specimens of 

 both sexes. About this colony on June 20 immature birds were seen on the 

 wing, following the parents and teasing for food, while others were still nest 

 building. When tired the young birds perched in the leafy tops of trees. 



A few of these swallows appear to be changing their nesting habits and 

 method of nest construction by taking advantage of shelters provided by man. 

 Inside the train shed of the Linea Ferrea del Oeste at Bayamon was a small 

 colony building against the rafters, and one pair had built on a beam in the 

 gable of a neighboring hotel. The nests were globular in shape, only two being 

 seen with the long bottle neck found in the nest of P. lunifrons, and those two 

 were imperfect. Most of these nests had only a large, roughly circular entrance 

 in the side, and a few were mere platforms of mud, hardly inclosed. 



The ordinary note of this swallow is a soft chu chu, and the males have a 

 chattering, twittering song given while flying. 



Food. — Thirty-six stomachs of this swallow were examined, taken in De- 

 cember and in the five months from April to August. The greater number were 

 secured in the western part of the island. In these, animal food forms the entire 

 content, as might be expected from observing the habits of the bird, vegetable 

 rubbish occurring in one stomach only, and then in such small amount as to be 

 inappreciable. Although true bugs (Hemiptera) and flies form goodly items, 

 the major share of the food is taken from the great army of beetles especially 

 common in tropical and subtropical regions. 



Orthopteran remains found in a single stomach taken in July form 1.39 per 

 cent of the total. Lantern flies (Fulgoridse) in 11 stomachs amount to 3.47 per 

 cent, and small species in allied families, with similar injurious habits, among 

 which may be mentioned jumping plant lice (Psyllidse), come to 1.08 per cent 

 more. Stinkbugs (Pentatomidas) occurred 16 times and figure as 7.63 per cent. 

 Most of them were eaten in June, and bugs of this family amount to 22.58 per 

 cent in that month. Bugs of the chinch-bug family (Lygseidaa) and others not 

 determined come to 3.25 per cent. 



Among the leaf beetles (Chrysomelida-), which form 8.06 per cent and which 

 were recognized in 22 stomachs, were the tobacco leaf -beetle (Epitrix parvula), 

 found four times; the bean leaf -beetle {Cerotoma denticornis) , likewise found 

 four times; and a flea beetle {Systena basalis), found seven times. Other 

 species were tortoise beetles (Coptocycla signifera), which attack the leaves of 

 the sweet potato, and a leaf eater (Myochrous sp.). Leaf beetles belonging to 

 the genus Cryptocephalus were found in 15 stomachs. Engraver beetles (Platy- 



