PHASES OF NATURE AROUND PRETORIA. 73 



stronger, and by the afternoon we were moderately 

 free. 



On May 25th we were again invaded, and again from 

 the same direction. We had learned from travellers of 

 the preceding day that another locust army was ap- 

 proaching, and a " transport rider " assured me that his 

 oxen had refused to go on against the dense moving 

 mass. This time the living cloud broke upon Pretoria 

 about 10 A.M., and had virtually passed from us by 

 3 P.M. * This swarm was afterwards reported from 

 Waterberg and Zoutpansberg, showing that its flight 

 was in a northerly direction. In the early part of 

 June, in crossing the Magaliesberg hills, I found them 

 somewhat plentiful in a defile on the summit. This 

 small colony were evidently stragglers from the higher 

 portion of the flight and had thus ceased to form part 

 of the main body, which was now some hundreds of 

 miles in advance. News was brought down to Pieters- 

 burg from the Spelonken that the locusts had been so 

 numerous as to prevent the informant driving a cart and 

 four horses against them {. On the journey to the Cape 

 in July I met with a considerable number near the 

 boundary of the Republic, a larger swarm the following 

 day about 50 miles beyond Kimberley, and another 

 swarm about 40 miles further south. All these were 

 flying northward, and would probably pursue the same 

 routes as their precursors. This was my last experience 

 of Pachytylus migrator oides. The year 1891 might be 

 styled by entomologists a " locust year," for Southern 

 Africa was not the only region invaded, and almost 

 simultaneous reports were received from Egypt and 

 India J. 



As the colder and dry season commences the natura- 



* Of this swarm a correspondent of the ' Transvaal Mining Argus ' calcu- 

 lated that he passed through a cloud of locusts 25 miles long, about a mile 

 and a half broad, and something under half a mile thick, giving about 12 

 cubic miles of locusts. Taking a low estimate he reckoned there would be 

 about 2000 locusts to every cubic yard (an estimate much too low), and 

 altogether he calculated that he must have passed over 130,842,144,000,000 

 locusts. 



t ' Zoutpansberg Review.' 



j ' Zoologist,' vol. xv. p. 221. 



