31 



The Threatened Plague of Locusts. — Jl. Bd. Agric. British Guiana, . 



Demerara, x, no. 3-4, April- July 1917, pp. 203-205. [Received L 

 20th November 1917.] 



The destructive South American locust, Schistocerca paranensis, has 

 suddenly made its appearance in various parts of British Guiana and 

 a notice has been issued by the Government economic biologist for 

 general information, giving some account of the life-history and habits 

 of this species and requesting that every effort should be made to 

 destroy the swarms immediately on their appearance. Its favourite 

 food-plants are said to be sweet and bitter cassava, maize, tannias, 

 rice and sugar-cane, as well as a number of weeds. 



The methods of control advocated include the collection, digging 

 up and destruction of eggs and kilUng the hoppers at night, when 

 they are found in dense masses, by surrounding them with dry foliage 

 soaked in kerosene oil and burning them, or by driving them into a 

 trench about 2 ft. \Wde and 3 ft. deep into which kerosene has been 

 poured and which can then be ignited. A solution of 4 lb. arsenate 

 of lead paste in 50 gals, water sprayed over the vegetation in the 

 immediate line of advance of the locusts is very efficacious in killing 

 them, while 1 lb. arsenite of soda dissolved in 4 gals, water with the 

 addition of 2 lb. molasses has been found most successful in other 

 paiis of the world. Paris green in the proportion of 1 lb. to 5 lb. of 

 lime may be dusted on the leaves on which the locusts are feeding. 

 All poisons should be applied in the early morning. The absolute 

 necessity for taking immediate action as soon as the swarms appear 

 is emphasised, otherwise the entire cultivated areas of the colony are 

 threatened. 



Baker (A. C). Life-History of Macrosiphum illirioisensis, the Grape- 

 vine Aphis. — Jl. Agric. Research, Washington, B.C., xi, no. 3, 

 15th October 1917, pp. 83-89, 2 plates. 



This paper describes the various forms of Macrosiphum ilUnoisensis, 

 Shinier, of which M. viticola, Thos., is a synonym. This Aphid is 

 \\idely distributed in the more southern of the United States. Eggs 

 are deposited generally during October upon the twigs of Viburnum, 

 prunifolium, the favourite position being close to the buds ; these 

 hatch during late March and early April, giving rise to the stem- 

 mothers. The young Aphids at once begin to feed on the buds and 

 later assemble in the flower clusters and devour the blossom stems ; 

 they also feed to some extent on the twigs and leaves. The five instars 

 of this form are described. Spring migrants apj)ear in the second 

 generation and are most abundant in the third in early May, after 

 which they gradually decrease. These migrants fly to wild and 

 cultivated grapes, being sometimes observed a mile distant from 

 Viburnum. Summer wingless forms occur in great abundance 

 throughout the summer, as many as seven generations frequently 

 reaching maturity by 1st July, while the mnged forms mature a day 

 or two later. Both forms do considerable damage to vines, attacking 

 the growing clusters and causing the berries to drop while still small 

 and green. The growing shoots and leaves are similarly attacked and 

 retarded in their growth. Intermediates between the summer winged 



