50 MR. C. B. HARDENBERG 



mg made by the young bagwornis. These are picked up 

 hy tlie Avind and distributed by the million to infest other 

 plantations. The moths of other species have a chance 

 to emerge and fiy away into neighbouring blocks before 

 the mass is set alighl and the result is that the fire de- 

 stroys — the empty bags and cocoons, plus any parasites 

 which may be present, as these usually make their 

 appearance long after the emergence of the moth. The 

 burning also destroys all fungus spores and disease germ« 

 which, as shown were on the increase when the planta- 

 tioji was n earing maturity. The only beneficial effect, 

 entomologically speaking, derived from the burning, is 

 the baking of The soil and the charring of the stumps and 

 even these advantages are less than would appear. The 

 heat does not penetrate deeply enough to reach those 

 insects which are living on the roots, killing only such 

 as are near the surface, and the latter are just the ones 

 which are more heavily parasitised as the Scolie does not 

 go deep into the soil lo hunt tlie cockchafer larvae And 

 the fire destroys friend and foe alike. 



The charring of the stumps will for a time effectively 

 prevent their being used as breeding places for wood bor- 

 ing beetles. But it also prevents them from rotting away 

 quickly, and before this process begins, cracks have 

 generally appeared in the charred surface, in which the 

 wood is exposed and by which the beetles may enter for 

 oviposition. In the case of stumps rotting quickly, the 

 beetles breeding therein would upon emergence not find 

 trees in the new plantation of sufficient size to tempt 

 them. But the charred stump remains longer and the 

 beetles which, after a time start breeding therein find, 

 when emerging, the new plantation well grown and con- 

 taining several sick and dead trees which will attract 

 them, Ttiid which, as shown above, act as centres of infes- 

 tation for the healthy trees around them. 



