During a portion of the year one may ascend the Rio Grande de Cagayan, the great river of northern Luzón, in a good-sized stern-wheel steamer for a distance of one hundred twenty miles, passing through a sparsely settled but potentially very rich agricultural district which now produces the best tobacco grown in the islands. It is a common thing for temporary residents in the Philippines to quote the foolish saying that the flowers are without odour and the birds without song. There is no more delicious fragrance than that given off in the evening by the shrub known as dama de noche. [156] The perfume made from ilang-ilang flowers goes all over the world. That extracted from the blossoms of the champaca brings fabulous prices. Jasmine is produced in abundance. If one wishes a heavier odour, tuberoses furnish it, while many species of trees make the whole forest fragrant when in flower. Some of the birds are sweet singers, while others brighten the landscape with their vivid colours. A row of snowy egrets, perched on the back of a carabao, presents a striking picture. One constantly hears by day the plaint of the limócon, a wood pigeon which exercises a most extraordinary influence over the lives of many of the wild people, for they believe that the direction and the nature of its notes augur good or ill for the enterprises which they have in hand. The crescendo shriek of a great black cuckoo, called by the natives bahów, commonly heard at night, is likely to cause alarm to one not cognizant of its origin, and has led many a sentry on a wild goose chase into a mangrove swamp in the belief that he was hastening to the rescue of some human being undergoing dreadful torment. One of the most interesting of the feathered denizens of Philippine fields and forests is the inconspicuous tailor bird, which carefully unwinds the silk from cocoons, and using it for thread, stitches together the edges of living leaves and then builds its nest in the green pocket thus formed. The insects are as varied and interesting as are the birds. There are very numerous species of ants, and the manifestations of their extraordinary intelligence are well worth careful observation. The work of the huge flocks of locusts which sometimes devastate the fields is worth seeing, although the sight is not a cheering one. There are butterflies and moths of great size and of the most brilliant and varied hues. Some of the very gaudily coloured species disappear as if by magic when they alight, because the under surfaces of their wings, exposed when they close them, perfectly resemble dead leaves. Other protectively coloured insects look marvellously like green leaves or dead twigs.