AN INVASION OF BRITISH GUIANA BY LOCUSTS. 349 



The manner of oviposition closely coincides with the published descriptions 

 of the process in other species in other parts of the world. The female, by means 

 of the four hardened processes with which the anal extremity is furnished, proceeds 

 to bore a hole in the ground by successively opening and shutting these appendages 

 accompanied by a downward boring movement. In favourable circumstances 

 the boring is complete within 15 minutes and the deposition of the ova commences. 

 If obstacles or interferences are experienced, or if the nature of the soil, weather 

 conditions, or other similar causes are unsuitable, the female either ceases her 

 movements for a period or moves off and elsewhere begins the performance afresh. 

 When the hole is complete the bottom is prepared for the reception of the eggs 

 by a quantity of white frothy substance which is voided by the female. This 

 substance when dry becomes spongy and slightly crisp. Eggs to the number of 

 about 50 or 60 are then laid, accompanied by a further supply of froth, which serves 

 to bind the mass together and, to some extent, forms a protective covering. Finally 

 a large quantity of froth is exuded which serves to isolate the mass from external 

 interferences. When the female withdraws her tail very few traces of her operations 

 are left. 



During the oviposition period the male is invariably in attendance, perched on 

 the back of the female, and vigorously withstands attempts at removal. His 

 presence at that particular time is inexplicable and apparently unnecessarj^. 



The depth of the boring varies, the average being about 2\ inches, and it is 

 directed slightly backwards. There is little doubt that the boring follows the 

 line of least resistance. 



•The mass soon dries and solidifies to such an extent that it is possible with the 

 exercise of a little care to remove the whole intact from the boring. This bundle 

 of eggs appears as a roughly formed cylinder conforming to the shape of the hole 

 in which it was deposited. Within the bundle the eggs point upwards at right 

 angles to the surface of the ground. After some days, when the eggs commence 

 to grow inside, they break away from the mass and remain as a loose heap within 

 the hole. 



Description of Ova. — On deposition the egg is 1 '9 mm. in breadth and 9 mm. in 

 length. The colour is a deep yellow, which becomes dull as the eggs increase in 

 age ; they finally turn a dull green colour and the eyes of the developing embryo 

 become conspicuous. The eggs gradually increase in size and at the time of hatching 

 both the length and breadth have increased by 2 mm. In shape they are not 

 unlike a cigar, but bluntly pointed at both ends and slightly curved. They are 

 popularly described locally as resembling a grain of rice. The surface of the egg 

 on magnification is seen to be very slightly roughened. 



Development of Ova. — The duration of the incubation period is about two or 

 three weeks, varying according to conditions of temperature and moisture. The 

 young locust ruptures the shell longitudinally. All the eggs in a mass hatch 

 at about the same time and the nymphs proceed to make their way slowly upward 

 to the surface of the soil, which procedure occupies some little time and is accom- 

 plished by continuous wriggling movements made in unison. The spot where a 

 number of young locusts have thus penetrated to the surface is indicated by the 



