549 



BiGALKE (R.). Common Potato Pests.^ //. Dept. Agric. Union S. 

 Africa, Pretoria, v, no. 2, August 1922, pp. 170-175, 2 figs. 



This paper has been compiled from various departmental publications 

 and deals with Hetcrodera radicicola, Greef (root gall-worm), Phthorimaea 

 operculella, Z. (potato tuber moth) and Epilachna dregei, Muls. (potato 

 Coccinellid). 



Pettey (F. W.). The Control o! Codling-moth in Pears in South 

 Africa. — //. Dept. Agric. Union S. Africa, Pretoria, v, no. 2, 

 August 1922, pp. 176-180. 2 figs. 



In trials lasting over three successive years it has been definitely 

 proved that dusting under South African conditions is less satisfactory 

 in the control of codling moth [Cydia pomonella, L.] than liquid spraying 

 when applied to pears, and is no more successful against the fungus, 

 Fusicladium. This may be partly due to the smooth nature of both 

 fruit and leaf as compared with apples, and also to the fact that there 

 are three generations of the moth in a season in South Africa. Dusting 

 on apples, in so far as it has been tried, has also proved a failure. It 

 is thought that this method will nevertheless be largely used in the 

 future against a variety of pests. 



Williams (R. H.). Locusts: Season 1921-23.—//. Dept. Agric. 

 Union S. Africa, Pretoria, v, no. 3, September 1922, pp. 218-230,. 

 10 figs. 



The locust season of 1921-22 was the worst in South Africa for over 



20 years. The theory that outbreaks of locusts follow a severe drought 



has been borne out on the present occasion, for the districts in which 



infestation was most intense were those that suffered severely from 



drought in 1919. It is thought that, in addition to the hatching of 



eggs that were laid by the swarms that escaped destruction in 1920-21, 



some of those that were deposited in the previous season did not 



get sufficient rain for hatching, and these also hatched during the 



present season. The poison-bait method of destroying locusts is. 



becoming more popular than spraying, though the latter has proved 



the most effective method of destroying the flying swarms while they 



are resting at night or in the early morning. A natural enemy that 



caused much destruction among the insects was the large fly, 



Wohlfahrtia hrunnipalpis, which deposits its larva on the back of the 



locust, attacking both the flying insects and also those in the last 



nymphal stage. A small black unidentified fly has been observed 



depositing eggs on the egg-masses of the locusts immediately they have 



been laid and before they have time to harden. The maggots of this. 



fly devour the eggs, as many as 75 per cent, having been destroyed 



in one district. The locust birds, Ciconia ciconia (European stork) 



and Ahdimia ahdimii (black stork), appeared in great numbers in 



January and February, following the flying swarms, until absence' of 



water eventually forced them to turn back. The small locust bird, 



Glareola melanoptera, was also seen, but the abnormally dry season 



had driven the majority away to places with more regular rainfall. 



The wattled starling {Creatophora carunctdatus), kestrels and hawks, 



also did some damage to the flying swarms. 



