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Speyer (E. K.). Tea Diseases. The Shot-hole Borer Investigation. — 

 Trojp. Agric, Peradeniya, xlviii, no. 3, March 1917, pp. 152-155. 

 [Received Ist May 1917.] 



This paper contains extracts from a preliminary report on the 

 shot-hole borer of tea, Xyleborus {Anisayidrus) fornicatus, Eichh. The 

 female beetle alone constructs a branched gallery, the entrance hole 

 of which constitutes the exit hole for the offspring when the latter 

 have attained maturity. The average time that elapses between the 

 entrance of the female beetle until the emergence of the adult of the 

 next brood is about 60 days. The female dies in the gallery after 

 emergence of the offspring. The average number of young found in 

 one gallery is 15. Four to six generations occur in one year, develop- 

 ment being less rapid in the wet season than in the dry. No definite 

 period of hibernation or aestivation has been traced. The insect 

 occurs up to an elevation of 4,800 feet in tea and 5,000 feet in castor- 

 oil plants, the development being slower at the higher elevations. 

 The female beetle, while boring, does not eat the wood excavated, but 

 while constructing the gallery deposits the spores of a fungus on the 

 gallery walls. This fungus gives rise to spores that provide food for 

 the larvae ; neither the larvae nor the young adult beetles excavate 

 or feed on any of the tissues of the plant. The damage done to the 

 trees in the process of boring is considerable. In the thinner branches 

 the presence of a horizontal circular gallery between the pith and 

 cambium causes the branches to break easily. While constructing the 

 gallery, the salivary juice of the female beetle causes a disturbance 

 in the tissues, leading to a staining of the wood and an abnormal 

 deposition of what is probably calcium carbonate in the tissues ; 

 rotting of the wood follows, causing much damage. The excavation 

 also causes a formation of wood to fill up the gallery ; this growth 

 should normally go to the production of leaf. Shade is no check on 

 the ravages of the borer. Two insects predaceous on X. fornicatus are 

 a species of thrips and a Trogositid beetle, but neither is sufficiently 

 numerous to be an efficient check. 



Experiments have shown that pruning causes a physiological 

 condition in the trees which renders them for a time immune from 

 attack. Later, generally about two to four months after pruning, the 

 borers begin to return from adjoining fields which have out-grown 

 their immunity or from bushes where the beetle can live through 

 periods closely follomng pruning, and the infestation then increases 

 rapidly until the time of pruning recurs. Various treatments of the 

 prunings have been tried. If the primings are buried, the borer 

 continues to live and breed in them for at least two months, and can 

 emerge through earth nine inches deep and even deeper. The 

 application of lime, basic slag and sulphate of potash to the buried 

 prunings has no effect on the borer. Sodium bisulphide and potassium 

 cyanide kill the insects in prunings, but these substances are costly 

 and dangerous to handle. As the borer can live in prunings left on 

 the ground, the woody parts should be destroyed -wnthin two days of 

 pruning. The practice of burning prunings is not found to have an 

 appreciable effect in controlling the beetle, while valuable organic 

 matter is lost by this method. AVhen disturbed by pruning, the insects 

 do not leave the plant, but push their way as far as nossible into their 



