GEEYBACK CANE BEETLE, LEPIDODEKMA ALBOHIRTUM. 25 



old. On lltli January, 1921, all the grubs were still in stage I; but on 

 18th January 12 per cent, of them had changed to stage II ; and by the 

 25tli of that month 27 per cent. 



As has been noted, the beetles Avere still on the feeding-trees on 

 8th Felu'uary, hence newly hatched grubs continued to be in evidence 

 when digging. Of those collected on that date, 26 per cent, were in the 

 first stage, 73 per cent, in the second, and 1 per cent, had already changed 

 to the third stage. 



On 24th February, however, no beetles were in evidence, though 

 23-5 per cent, of the grubs were in stage I, and only 54-2 per cent, in 

 stage II, because 22-3 per cent, had changed to stage III. A week later, 

 2nd March, 14 per cent, w^ere in stage I, 43 per cent, in stage II, and 

 41 per cent, in stage III. 



And finally, on 11th ]\larch, scarcely 1 per cent, of the grubs were 

 left in the first stage, a fact which is interesting since this was only 

 about a month after the last straggling beetles were seen on the feeding- 

 trees, for it goes to show how brief is the first stage ; 26 per cent, were in 

 the second stage, and 73 per cent, had already developed into the third, 

 the really destructive stage. 



From these data it would apparently only require approximately a 

 month for each of the first two stages. The third or final stage of the 

 grub, however, remains active among the roots of the plant right up to 

 the time that the cold nights of IMay or June set in, before descending to 

 hibernate ; hence the duration of this stage is fully three to four months, 

 or considerably more if we take into account the time spent in the 

 hibernating chamber before pupation takes place. 



These grubs, like those of all related species in various parts of the 

 world, are not primarily addicted to feeding upon living roots, but 

 normally depend upon the decaying organic matter in the soil for their 

 food. As Girault and Dodd (66) have well stated — 



"They are continually passing large ciuantities of soil through their 

 bodies, altering to a certain extent, no doubt, its chemical nature and 

 considerably changing its physical texture. This alteration is brought 

 about by the fact that the organic matter of the ingested soil is partially 

 digested and used as food while the soil is expelled from the anus in the 

 form of a pellet. This constant movement of soil through their bodies, 

 combined with the loosening effect on the soil of locomotory movements 

 of the legs and mandil)les, must have in the long run an important effect 

 on the character of soils in a grub-infested area. But, unlike earth- 

 worms, grubs do not to any extent transport soil from beneath to the 

 surface. 



"The following evidence has been collected to show that the grubs 

 subsist largely upon organic matter in the soil, attacking living vegetation 

 at the same time but not constantly and habitually. Habitually and 

 constantly, they are swallowing soil, extracting ])artially its organic 

 content, yet a supply of living vegetation seems necessary for their normal 

 development : — 



(1) Young larva^ when hatched are wholly white, and remain so 

 until placed into bare soil, after which, in the course of a day 

 or so, they become coloured — the colour due to soil Avhich has 

 been ingested. That they are not starved is shown by their 

 growth and appearance. 



