They passed the enclosure, and a little farther on there was a group of Indians engaged in pounding rice to separate the grain from the husk. The apparatus was exceedingly primitive, being simply a mortar with a heavy pestle, which was raised in the air and then brought down with all the power of the person who was wielding it. Just then the Doctor and Mr. Segovia rode up, and the latter explained that, while mills for cleaning rice were in use all over the islands wherever rice was grown, many of the natives preferred the old process, and were contented with the mortar and pestle. "In the back regions," said he, "where mills are scarce, they thrash the rice from the stalk by treading it out with buffaloes, and remove the hulls as you see them now." Frank asked if there was any variation in the rice-crop from year to year, so as to make its cultivation a matter of uncertainty. [Illustration: THE PHILIPPINE LOCUST.] "There is not much variation," said the gentleman, "but we can never be certain of a crop till it is gathered. A short supply of water may dry up the fields, and too much rain may inundate them and wash the plants out, but this is not often. The greatest uncertainty is with the locusts, as they come suddenly, and sometimes destroy an entire crop in a day or two." "How often do you have the locusts?" one of the boys asked. "About once in seven years," was the reply. "They come from the islands farther south, and you can hardly realize the desolation they make till you have seen it. A reddish-colored cloud is seen on the horizon; it comes nearer and nearer, and is frequently ten or twelve miles from one side to the other, and occupies five or six hours in passing over. This cloud is formed of millions and millions of locusts, and sometimes it is so dense that the sun is darkened the same as when a thunder-shower rises. If the locusts perceive a green field they fall upon it, and in an hour every vestige of verdure has disappeared; then they rise and move on to join their companions in the air, and the different parts of the column seem to take turns in feeding. When enough have come down to cover a field, the rest move on, and those who have satisfied their appetites take their places in the rear. In the evening they halt in a forest and rest on the limbs of the trees, and frequently so many of them cover a limb that it breaks off and falls to the ground. When they leave in the morning, the forest looks as though every tree had been struck and shattered by lightning; the leaves are all gone, the limbs are broken, and the ground is strewn with the scattered fragments. At certain periods they remain on broad plains, or the sides of fertile mountains, and lay their eggs. Three weeks later the eggs are hatched, and the young locusts appear; they live upon whatever green food they can find till their wings are formed, and then they fly away to do their work of devastation."