LIKE AN ARMY

Evening Star, Issue 21935, 23 January 1935, Page 4

LIKE AN ARMY

HOW THE GRASSHOPPERS ADVANCE “ Grasshoppers—First turn left.” This notice appeared on a scrap ct paper that Wits spiked on a branch propped up on a road west of Mildura last week (writes J. A. Baker in the Melbourne ‘ Argus It was in Miliewa, where dwarfed euealypts arc scattered over the red soil of ridge and Hat, and the rainfall is the lowest in Victoria. Three weeks ago the pastoral lauds of this country were at their best. The late rains had caused a luxuriant growth of native grasses, and farmers had thrice the amount ol feed they required for their stock. Now some of them have not a green plant on their properties, for the rain which brought the pastures brought with it armies of grasshoppers; and olio of the habits of the grasshopper is to devour every green thing in its path. It lias become the fashion to speak in military terms of the swarms (,f grasshoppers which have infested the north-west of Victoria recently, for there is an uncanny order and precision about their movements. A swarm of grasshoppers is an ordered colony, with a definite objective, and its members do all they can to ensure that this objective is reached. The eggs are laid together in patches, which are always on bare ground. Little holes are made for the eggs in the untillod soil, and from the beginning the insects are crowded together in a colony. So, after hatching, the young hoppers are ready to move forward together on a front. The vanguard is composed of the strongest and fittest, and it generally extends back for about twenty chains. Then there is a section of “ followers,” moving along steadily to join the advance bodyt After these come the weaklings and stragglers, which generally die on the land that has been eaten out by the others. The army moves about half a mile a day, resting at night. Owing probably to the fact that their range is limited, the hoppers will oat any green thing. Last week I visited the farm of a settler at Benetook. An army had eaten him out. First the grasshoppers ate 500 acres of luxuriant pasture,_ and then 300 acres of wheat. Not satisfied, the insects turned to his large vegetable garden, which provided a savoury. Thev ate all the broad beans, but, strangely, avoided a bed of_ French beans. Then they devoured ci isp lettuce, silver beet, and mint and stripped large cabbages to the stalks. They wiped out a hedge of sunflowers, and made the ruin complete by defoliating a vine and an orange tree. Now, from the doorstep to the boundary fence, the farm is as bare as a fallow. DEVOURING WHEAT CROPS. Sometimes an army will pass through a wheat crop, stripping tthe flag from the plant, and leaving the head waving curiously on the spindly stem. Another army may eat the grain as well, and the most voracious cat flag, head, and stalk to the yellow earth. Ultimately the army becomes winged, and its object then is to rise as one huge mating swarm. But the winged insects will not leave the hoppers until most of these are able to fly. As they can cover far more ground in the winged form, the insects are more discriminating in their choice of food ; they avoid unpalatable plants, unlike the hoppers, which eat even wiki mustard. Wings are tested by short excursions, and the insects always fly with the wind. When they land they turn their bodies, so that all their heads are facing the breeze, and often they may he seen in this position in parallel rows on a sand hill, basking in the warm •sunshine. Winged forms dislike the wind, and they take shelter from it along fences in masses extending for hundreds of yards. It is said that they also dislike noise. There are several species of smaller animals that attack grasshoppers. Mites hang to their legs, and prevent them from hopping far. Insects, including an ichneumon and a braconid fly, parasitise them. Then above an array may be seen sometimes a flock of starlings, _ wheeling and diving, in mass formation, and harassing the colony. FUNGUS OF DESTRUCTION. Many years ago a fungus was introduced by the Department of Agriculture from South Africa, and experiments were conducted at Rochester in 1899. The fungus which is known as bread fungus, because it may be grown easily on a paste of bread and water, grows within their bodies, and it may be spread through a colony by infected insects. The efficiency of the fungus, however, varies greatly with the humidity, and, as a method of control, it gives erratic results, except in southern districts, where its effect is most marked. Eggs of grasshoppers are eaten by birds, but it is after hatching that the greatest mortality occurs. Generally in November the grass is dry, and countless numbers of young grasshoppers die of starvation. This year late rains caused an abundance of feed, on which they thrived. It required an intensive campaign of poisoning to prevent an advance on the vines and citrus of the rich irrigation settlements around Mildura. When they have been poisoned many hoppers crawl to die in the shelter of trees or beneath logs. On the ground the insects move in many directions, and in the air the winged forms fly aimlessly about. The attacking fronts of the hoppers are broken, and the organisation of the colony is destroyed.