The Defensa Agricola continued its work, however, unheeding of such protests; and now, for some time past, may be said to have fully justified its existence and its methods by results in both countries. It has its centres of observation, like any other force prepared to repel invasion, and, on the coming of a swarm being signalled, every human being in its course is called upon to aid in the defence. The plan of this defence consists, briefly, in driving and sweeping the insects into trenches backed with long lines of sheets of corrugated iron, placed together end to end. Once gathered into these trenches the locusts are burned; and by the untiring continuance of this process they are gradually destroyed before much damage (very small indeed compared with the ravages of pre-Defensa Agricola days) has been done. The sweeping-up process can be usefully employed for the extermination of settled swarms otherwise its members will quickly proceed to deposit eggs which later would hatch into young “hoppers” born with infinitely more voracious appetites than even their parents had.[39] Locusts, as has been seen, come from the North and in the normal course of their nature would disappear again in that direction, leaving bare fields and their hungry young behind them in memory of their visit. Still in recent years, before the full development of the Defensa Agricola, it appeared that locusts had actually become acclimatized in some regions of both Republics, notably in the Southern part of the Province of Buenos Aires and in the Territory of the Rio Negro, and therefore did not return North but managed to survive frost. This last menace may now, however, be considered as past. The Defensa Agricola does not only devote its attention to locusts. It possesses a highly trained scientific staff which combats the invasions of all the other insect pests which from time to time threaten the crops, vines or fruit and other trees and useful vegetation. It issues clear instructions as to the treatment to be applied in each case and punishes noncompliance with its orders by fines which it is empowered to inflict. Agriculture has much for which to thank this Institution in respect of protection against pests; the danger from which was increasing with the importation of vines and fruit trees from other countries.