20i! 



THE AGRICULTURAL NEWS 



Juke 29, 191S. 



INSECT NOTES. 



THE SOUTH AMERICAN LOCUST 

 BRITISH GUIANA 



IN 



Towards the end of June 1917 liritish Ouiana was 

 TisileJ by a vast svarm of locusts which entered the North 

 West J iistrict from Venezuela, and spread down to the inouth 

 of the Pomeroon River and tlie Essequebo Coist. An interest- 

 ing account of this invasion is given by Mr. G. K. Bodkin, 

 Government Economic Hiologist of British Guiana, who bad 

 the opportunity of observing the swarm in most of the invad- 

 ed districts soon after its arrival. (Journal of the Board of 

 A^ruulture of British Guiana, Vol. XI, No. 1, January 

 1918.) A previous notice of the arrival of this locust 

 (Schisiocerca J'aiaiiensis) appeared in the above journal for 

 April and July 1917. 



The swarm was de.scribed by eye- witnesses in various 

 ways; 'some likened it to a cloud in the sky which temporarily 

 obliterated the light of the sun, while the sound of their flight 

 is well represented by the wind-stirred rustlings of a multitude 

 of dead and dried leaves evenly sustained and heard from afar.' 

 The locusts gradually distributed themselves over a large 

 area, and almost every cleared and cultivated piece of land on 

 the forest received its detachment. It is considered that this 

 vast swarm originated on some of the large islands at the 

 mouth of the Orinoco, and a portion of the swarm is known to 

 have reached the Penal Settlement on Essequebo Kiver some 

 200 miles to the south-east. These locusts covered most of 

 this distance in flight against the wind. As each detachment 

 settled down the insects immediately began feeding greedily. 

 Indian corn and cassava seem to have been preferred in 

 almost every instance, and these crops were quickly stripped 

 of all foliage. Feeding was done largely at night. When dis- 

 turbed, the adults flew strongly, and invariably went ofl'down 

 wind, so that capture was extremely difficult. Therefore, 

 hardly any attempts were made to control the swarm at the 

 time of the invasion, since the cost of the labour expended 

 would have been out of all proportion to the number of 

 locusts destroyed. Within a fortnight of their arrival 

 the two sexes were observed mating, and egg-laying began. 

 The eggs are deposited beneath the surface of the soil, 

 the female boring a hole by means of certain liardened 

 processes at the tail end of the body. A depth of from 

 1§ to 2 inches is reached, and oviposition begin.s. The 

 female first exudes a small quantity of froth and then 

 lays her eggs rapidly, mixing them with more froth. Finally 

 a large quantity of froth is exuded to seal the hole. The 

 froth soon hardens, forming a protective covering for the eggs, 

 and causing them to adhere together in a rough cylindrical 

 mass, conforming to the .shape of the hole. Mr. Bodkin 

 mentions that in spite of thcie precautions the eggs may be 

 attacked by enemies, an egg-parasite having been bred out 

 from a mass of these eggs dug up in a field in the North 

 West District. 



It was observed that on the pegass soils in this district 

 egg-laying took place on the drier and more rigid patches. 

 The writer continues: 'A favourite locality seemed to be 

 where a palm had originally 8too<l, and the network of 

 decaying roots mixed with soil was almost universally selected. 

 The somewhat higher ground on the edge of the draining 

 trenches, and on the drains themselves, was also utilized. Gn 

 the sandy soils which prevail in certain districts the eggs 

 were deposited in any open space. During tke early evening 

 hours from about -i.-'JO to .0.30 this operation took place. An 

 open piece of sandy soil with several hundreds of locusts all 



busy ovipositing presented a most peculiar spectacle. So 

 engrossed were the locusts in their occupation that it was an 

 easy matter to seize them between the finger and thumb and 

 forcibly remove them.' 



It is stated that the eggs are about the size of a well 

 matured grain of rice, and of a dull yellowish-brown colour. 

 During development they increase slightly in size and become 

 softer, while a greenish tint appears. Finally the eyes of the 

 embryo can be seen through the shell. In the process of 

 emerging the young locust ruptures the shell longitudinally. 



Mr. Bodkin found that none of the farmers whose land 

 was invaded by the locusts had any idea of the real signifi- 

 cance (.f the vast swarm, and of its capabilities of s idden 

 enormous increase. So that when the young hoppers began 

 to emerge in countless numbers, there was general disillusion- 

 ment and consternation, and the question of control 

 immediately became urgent. 



A number of control methods were devised to meet the 

 varying local conditions, and were everywhere effective. 

 During the dry weather large numbers of the young locusts, 

 or .'hoppers', could be destroyed by burning. Whenever a 

 large swarm was found it was surrounded by dry and 

 inflammable bush, which was then fired. This method was 

 very effective against the younger stages up to the third 

 stage, but the older hoppers were in many cases able to 

 jump through the ring of fire and escape. It was found 

 that it was useless to burn a swarm in high gr.ass, since the 

 majority made their way down to the damp tangled growth 

 at the roots, and thus avoided tiie fire. 



Various methods of trapping the young hoppers 

 were tried with excellent results. Small canvas sheets, 

 banana leaves, etc., were smeared with tar, and clusters of 

 young locusts were brushed off to these tarred surfaces, 

 where tliey stuck and soon died. 



In another district the insects were driven into draining 

 trenches where the surface of the water had previously been 

 covered with a film of kerosene, and were effectively killed. 



The following ingenious method of control is described 

 by the writer as being introduced by Mr. E. S. Nicholson, of 

 of Anna Regina: 'Tarpaulins about 12 feet square were 

 smeared with the thickest molasses. A large swarm of 

 hoppers having been located, this sheet was laid out on the 

 ground in the proposed direction of the drive. The swarm 

 was then surrounded by a number of individuals and gently 

 yet firmly urged towards the tarpaulin. Obviously this 

 method can only be exercised where the terrain is only 

 slightly encumbered by vcget.ation. It would be quite 

 impossible, for instance, to utilize such a means in high 

 grass. For wholesale destruction of well matured hoppers 

 in large swarms this method cannot be approached.' 



Poisons were used to a very small extent by the people, 

 although abundant sui)plies of these were available from the 

 Governmpnt at half the original cost price. This was 

 attributed to the fact that many of the small land-owners can 

 barely eke out an existence, and that they are probably unfami- 

 liar with the handling of poisons. 



In some instances it was found necessary to deal with 

 recalcitrant land-owners under the Insect Pests and Plant 

 Diseases (Prevention) Ordinance, which in 101 1 became a 

 law of British Guiana. ]5ut in the great majority of cases 

 the small farmers and grant-holders co-operated to combat 

 the locust invasion, and thus averted a danger which menaced 

 the whole colony. With the exception of two districts 

 where the hoppers have reached the adult stage and are thus 

 capable of flight, the pest has been eliminated from British 

 Guiana. 



J.C.H. 



