RUBBER 623 



hole-borer " of the tea plant, where it is believed to 

 attack the young larvae of the beetle. 



Coleoptera. 



This Order of insects, containing as it does the whole 

 tribe of beetles, provides the largest number of names on 

 our list. 



The grubs of various Melolonthidae (Cockchafers) attack 

 the roots of young Hevea plants. Of these, the larvae 

 of Lepidiota pinguis is the most troublesome in Ceylon, 

 and is sometimes responsible for a large number of 

 vacancies in a new clearing. It is a large white grub, 

 measuring about 3 in. in length. The beetle, which 

 attains a large size, flies at dusk, and lays its eggs just 

 below the surface of the ground. The newly hatched 

 larvae burrow down into the soil and attack the roots of 

 the neighbouring plants. The insect by no means 

 confines its attention to Hevea plants. It is probably 

 more or less omnivorous. It was at one time a notorious 

 coffee pest, and is now a serious enemy of cinnamon in 

 the low-country of Ceylon. Its appearance in large 

 numbers in rubber clearings is probably due to the facility 

 with which the beetle is enabled to deposit its eggs in 

 the newly turned soil immediately surrounding the young 

 plants. The clean weeding of clearings also tends to 

 concentrate the grubs at the roots of the rubber plants. 

 If there is an insufficiency of food at one spot, the grubs 

 will come up to the surface and wander to adjoining 

 plants. The tap root of the rubber plant is often eaten 

 clean off to within an inch of the surface of the soil. One 

 of my correspondents informed me that he had lost 3,000 

 plants in a single clearing, and had extracted five or six 

 of the grubs from each hole. I have received no reports 

 of damage to older trees. 



Nitrate of soda has a well-marked effect in ridding the 

 soil of insects, besides being a useful fertilizer. It may 

 be applied at the rate of i to 2 oz. for each plant. A 

 correspondent to whom I recommended this treatment 

 reported that the grubs quickly deserted the hole's treated 

 with this substance. " Vaporite," a patent insecticide, 

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