In some seasons in August and September, after a period of warm wet weather, the larvæ of the large horned beetle rise to the surface, throwing up little mounds of earth as moles do; often they are so numerous as to give the plains, where the grass has been very closely cropped, the appearance of being covered with mud. These insects afford a rich harvest to the Spur-winged Lapwing (_Vanellus cayennensis_), which in such seasons of plenty are to be seen all day diligently running about, probing and dislodging them from beneath the fresh hillocks. The Gulls, unprovided with a probing beak, avail themselves of their superior cunning and violence to rob the Lapwings; and I have often watched their proceedings for hours with the greatest interest. Hundreds of Lapwings are perhaps visible running busily about on all sides; near each one a Gull is quietly stationed, watching the movements of its intended dupe with the closest attention. The instant a great snow-white grub is extracted the Gull makes a rush to seize it, the Lapwing flies, and a violent chase ensues. After a hundred vain doublings the Plover drops the prize, and slopes toward the earth with a disappointed cry; the pursuer checks his flight, hovers a moment watching the grub fall, then drops down upon it, gobbles it up, and hastens after the Lapwing to resume his watch. Many of these Gulls haunt the estancias to feed on the garbage usually found in abundance about cattle-breeding establishments. When a cow is slaughtered they collect in large numbers and quarrel with the domestic poultry over the offal. They are also faithful attendants at the shepherd's hut; and if a dead lamb remains in the fold when the flock goes to pasture they regale on it in company with the Chimango. The great _Saladeros_, or slaughter-grounds, which were formerly close to Buenos Ayres, are also frequented by hosts of these neat and beautiful scavengers. Here numbers may be seen hovering overhead, and mingling their excited screams with the bellowing of half-wild cattle and the shouts of the slaughterers at their rough work; and at intervals, wherever a little space is allowed them, dropping themselves on to the ground, which reeks with blood and offal, and greedily snatching up whatever morsels they can on the instant, and yet getting no stain or speck on their delicate dress of lily-white and ethereal blue.