THE YEGpyj'ATlON OF NATAL. 291 



rapid. The bacteriolog-y of the soil is a subject that would 

 repay attention. 



Though the white ant prefers dead wood it also attacks 

 living trees, cutting the bark below the surface of the soil, 

 and ultimately killing them. 



2. Locusts. — During the last few years systematic poison- 

 ing by means of arsenic solutions, petroleum, and infecting 

 with a parasitic fungus has led to a considerable diminution in 

 this pest ; but formerly locust swarms wrought considerable 

 destruction. A large swarm of locusts forming a dense cloud, 

 say, a mile long and half a mile wide, would destroy prac- 

 tically all the foliage in the track which it traversed. Mr. 

 Sim, however, informs me that he has noticed cases where 

 only certain plants were eaten, while the others were 

 untouched. 



3. Cateepillaks. — There are, of course, niimerous insect 

 pests which cannot be mentioned here. It may, however, be 

 noted that the larva of a Psychid moth (Animula sp.), 

 known as the bag-worm, which is really a thorn-tree insect, 

 sometimes causes considerable damage to wattle plantations 

 owing to its excessive abundance. The caterpillar of the 

 Saturnid moth (Nudaurelia belina Westiv.) in certain 

 seasons is very plentiful, and strips the foliage of trees, 

 especially that of the oak. The larva of the so-called Procession 

 moth (Anaphe panda), which forms a rounded colonial 

 cocoon some 6-7 in. in diameter, may be very numerous ai)d 

 destructive. 



4. Eaethworms. — A large species of earthworm, which 

 grows to the length of a yard, carries up much soil from 

 the subsoil, and forms large castings which sometimes 

 accumulate in great quantities. In some places many tons of 

 soil per acre are thus brought to the surface in a single 

 season. Where it occurs the effect is most striking ; but the 

 worm is local and does not seem to be at all generally distri- 

 buted through Natal. Where it is found the soil is usually of 

 the loose type. Another species of earthworm lives in the 

 vleis, and it is said to produce those curious humps 



