and Magazine of the Ceylon Agricultural Society. 



297 



When a plant is stumped, the cut end usually 

 dies back to the next node, from which the new 

 shoots will be produced. It is the dead pith in 

 this dry portion that attracts the insects. They 

 will not commence burrowing into the living 

 sappy stems, nor will they enter by any but a 

 cut or broken surface. It is possible that the 

 excavation of the centre of the dead part may 

 lead to an extension of the decay, but this has 

 not been proved. Any possible danger from this 

 cause may be prevented by stumping the plant 

 immediately above the node, leaving, say, half- 

 an-inch to prevent chance of injury. There 

 would then be little or no dead wood to attract 

 the insects. Where this precaution has not been 

 taken, the terminal dead parts should be cut or 

 broken off as soon as they are thoroughly dry. 



(5) The deserted tunnels of these wasps and 

 bees are sometimes tenanted by a species of 

 Thrips, which has consequently been regarded 

 with suspicion. But this particular species is 

 quite harmless, and may indeed be a friend 

 rather than an enemy. It is an insinuating 

 little creature, and penetrates into the galleries 

 of the "Shot-hole Borer" in tea, where it is 

 believed to attack the young larvre of the beetle. 



(6) I have on more than one occasion re- 

 ceived reports of reputed damage to rubber 

 plants and stumps by Dragon flies, which are 

 said to be found perched on the ends of the 

 stumps engaged in sucking the sap. This is, of 

 course, an error of observation. Dragon flies 

 are purely insectivorous, and, far from occasion- 

 ing any injury, should be regarded as highly 

 beneficial insects. They are fond of taking up 

 their position on any vantage ground, from 

 which an uninterrupted view is obtainable on 

 all sides. This will account for their presence 

 on the end of the rubber stumps. From such 

 a perch they would be ready to pounce upon 

 any smaller insect that might come within 

 their range of vision. 



(8) " Black Bug" [Lecanium nigrum, Nietner). 

 — This common and almost omnivorous scale 

 bug occasionally occurs on the terminal branches 

 of the Hevea plant. On young plants it will be 

 sufficient to rub off the scales with a piece of 

 sacking. On older plants it can be checked by 

 spraying with MacDougall's solution (in the pro- 

 portion of 1 lb. to 5 gallons of water). 



IV. — Foliage and Terminal Buds. 



(1) " Spotted Locust " Aularches militaris, L.) 

 — This conspicuous locust has occasionally been 

 known to attack the foliage of young rubber 

 plants, but such an occurrence appears to be ex- 

 ceptional. Though the locusts are sometimes 

 present in enormous numbers on cacao estates 

 interplanted with Hevea, they usually ignore 

 both the cacao and the rubber, confining their 

 attentions to the foliage of the shade trees. 



Several smaller species of acridiid grasshop- 

 pers are sometimes destructive in young nurse- 

 ries, defoliating the seedlings. Poisoned baits, 

 as recommended in section III. (No. 2), should 

 be employed to check this pest. 



(2) Two plant-sucking bugs (the " Rice Sap- 

 per," Leptocorisa acuta, Thunb, and Callicratidcs 

 rama, Kirby) have been credited with injury to 

 the foliage of Hevea seedlings in the nursery. 



The plants submitted as specimens were minu- 

 tely punctured, but the punctures were not of 

 insect origin at all, being caused by a spot fun- 

 gus. At the same time it was proved (by keeping 

 the insects in captivity) that the Leptocorisa 

 will puncture the soft parts of the stem, causing 

 the terminal shoot to wilt and droop. Damage 

 from this cause can be prevented by lightly 

 sweeping a butterfly net over the surface of the 

 growing seedlings. The insects will fall into the 

 net and can be destroyed by hand. 



(3) "Scale Bugs" (Qoccidce). — Only two species 

 {Lecanium niqrum and an undescribed species 

 of Mytilaspis) have been observed upon the 

 leaves, and these in such very small numbers as 

 to bo practically negligible. 



(4) Leaf-eating Caterpillars. — There is no 

 single species that has a preference for 

 the foliage of Hevea brasilicnsis. — The 

 few that have been recorded are mere 

 casual visitors ; but every caterpillar fouud 

 actually feeding upon the plant must be regarded 

 as a potential enemy and destroyed at sight. 



" Tussar Silkworm" (Antheraia paphia, Linn.). 

 — A large and conspicuous green caterpillar, 

 with two rows of orange-tipped tubercles on 

 the back. If a diet of rubber leaves would 

 add elasticity to the secreted silk, it might 

 be of advantage to . raise' silkworms on spare 

 rubber foliage, but such a result is extremely 

 problematical. 



"Large Bagworm" (Clania variegata). — The 

 caterpillar conceals itself in a tough silken 

 case intermingled with pieces of leaves and 

 fragments of stick. 



(5) "Pigmy Rose Beetle" (Cingala tenella, 

 Blanchard). — Specimens of this tiny beetle were 

 submitted to me, together with leaves from 

 young plants upon which they had been feeding. 

 The latter showed numerous small irregular 

 perforations. On arrival the insects were all 

 dead, and so firmly glued to the leaves by 

 coagulated latex that it was impossible to remove 

 them without the loss of most of their limbs. 



V, — Animals Affecting the Latex and 

 Manufactured Rubber. 



I have very few records under this section, 

 but one of them is of some interest. 



(1) "Slugs" (Limax, sp). — A correspondent sent 

 me specimensof a slug with the complaint that 

 these animals visited the recently-tapped rubber 

 trees and lapped up the remains of the latex 

 left in the wounds, wich the result that the 

 amount of scrap rubber was considerably re- 

 duced. Some of these slugs were confined in a 

 cage, together with a small saucer of fresh latex. 

 Its presence was almost immediately scented 

 out by them. One of them drank for about ten 

 minutes with no subsequent derangement of its 

 digestive organs. 



Quicklime is a recognised deterrent against 

 slus;s, but in this climate would- become 

 slaked too rapidly to be of much practical 

 use. Many slugs have the power of shed- 

 ding off obnoxious material with a copious 

 secretion of slime, but this power is weakened 

 with each repetition of its exercise and 

 requires time for recuperation. A sprinkling 

 of "vaporite" around the base of the tapped 



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