136 



[August, 1909. 



PLANT SANITATION. 



ENTOMOLOGICAL NOTES. 



By E. Ernest Green, 

 Government Entomologist. 



I have examined fresh samples of the 

 tea seedlings infested by ' Eel worm' 

 (mentioned in last month's Notes). 

 These had been gathered from different 

 plots and prove that the whole nursery 

 is equally affected. 1 have also been 

 able to determine that the soecies 

 is the common 'Root-knot' Eel worm' 

 (Heterodera radicicola) which occurs 

 practically all over the world. In Ceylon 

 it has long been known to attack the 

 roots of various garden plants and vege- 

 tables. In the present case the en- 

 cysted female worms were found in 

 numbers, occupying small cells in the 

 bark and cambium of the diseased roots. 

 A circular on this pest is being prepared 

 and will be issued shortly. 



Larger numbers of the young brood 

 of the 'Spotted Locust' (Aularchus 

 vnilitaris) have attracted attention on an 

 estate in the Rattota district. They 

 are reported to be defoliating ' Dadap ' 

 (Erythrina) and Cinchona trees and to 

 be sampling the tea, but without doing 

 any serious damage to the last plant. 

 The life history of this locust has been 

 worked out. A single brood only is 

 produced during the twelve months. 

 The eggs are deposited in the ground in 

 October and November ; the young 

 locusts hatch out in the following March, 

 and gradually increase in size until 

 August or September, when the adult 

 winged insects appear ; pairing and 

 egg-laying complete the cycle in Octo- 

 ber and November again. These dates 

 have been found to be fairly constant 

 for the Kandy, Matale and Rambukkaua 

 districts; but they may very possibly 

 vary in other parts of the Island, 

 where the incidence of the monsoons is 

 different. It is important to remember 

 that it is the egg-laying period that is the 

 most vulnerable point in the cycle. The 

 eggs are always deposited in circum- 

 scribed areas of ground which — with 

 ordinary cai'e — may be located quite 

 easily. It these spots are forked to a 

 depth of about twelve inches and treated, 

 with quick-lime, very few of the eggs 

 will hatch out. 



Specimens of the 'Fringed Nettle- 

 grub " (Natada nararia) have been re- 

 ceived from Elkaduwa, where it is said 

 to have spread over ten acres of tea. 

 This is the species that sometimes gives 

 considerable trouble on the Badulla 



and Haputale side of the Island ; but 

 its attacks seem to be less frequent and 

 less severe in the Central Provinces. 



The large hairy caterpillars of Suana 

 concolor occasionally attract attention 

 by their depredations upon various cul- 

 tivated plants. A native cultivator 

 from Harispattu submits specimens of 

 this caterpillar for determination, and 

 reports that they have eaten up a num- 

 ber of his cacao plants. They seldom 

 occur in sufficient numbers to be a 

 serious pest, but their large size and 

 hearty appetite seldom fail to attract 

 a ttention. Their very size is a safeguard, 

 as they are easily seen and can then be 

 picked off aud destroyed. Care should 

 be taken in handling them, as they are 

 armed with a band of short but very 

 sharp black hairs which can cause painful 

 irritation. 



Two separate correspondents have 

 sent me specimens of the large white 

 grubs of a Longicorn beetle, extracted 

 from the stems of dead or dying rubber 

 (Flevea) trees. The symptoms in each 

 case make it tolerably sure that the 

 tree had previously been attacked by 

 some other disease, and that these insects 

 had made ^cheir entry subsequently. I 

 have not yet received satisfactory 

 evidence of any boring insect being able 

 to penetrate the latex-bearing tissues of 

 a healthy rubber plant without being 

 eugulphed in the consequent flow of 

 latex. 



But a new rubber pest has put in an 

 appearance in the form of a species of 

 slug. My 2orrespondent describes it as 

 "a white snail about 1^ in. long," but 

 subsequent enquiries showed that the 

 creature was uot possessed of a shell. He 

 continues, " I caught one on the top of a 

 tree, ' in flagrante delictu,' and found the 

 same species at the bottom of each 

 damaged tree. They creep up the stems 

 at night and in the early morning, and 

 nibble off all the tender shoots just 

 breaking away, and the rubber plant 

 or young tree hangs fire aud cannot get 

 a start. Some of the tops of the plants 

 were transformed into green rods — full 

 of sap — but with no growing points left. 

 When the terminal growing point is 

 destroyed the plant attempts growth 

 at each axil lower down, only to be 

 foiled every time by the snail." The 

 slugs are said to retire into the grass or 

 under dead leaves at the base of the 

 tiees during the daytime. The logical 

 remedy will be to keep a clear space of 

 bare earth around each tree and to 

 sprinkle this occasionally with lime. 



