51 



genus Chlorophorus, and is considered identical with the species from 

 Tonkin described by Fairmaire as Chlorophorus ionkinensis. 



Numerous experiments have been made with the object of discovering 

 the food-plants of X. quadripes other than coffee. Some evidence 

 was obtained of oviposition on a wild species of Gardenia, and o\riposi- 

 tion on a cultivated Gardenia was observed one hour after the intro- 

 duction of adults of X. quadripes. Tea plants also became readily 

 infested in the experiment cages, while several species of Ixora have 

 been attacked by the larvae, without, however, any adults being 

 obtained. 



The description of X. quadripes, Chevr.. given by Bourgoin is 

 quoted, and it is stated that it does not apply exactly to the coffee- 

 borer of Tonkin, particularly as regards coloration, the insect •being 

 very variable in this respect, as well as in form and size. 



Only one species of coffee-plant, Coffea arabica, is as yet regularly 

 attacked at Tonkin by X. quadripes and the question has been con- 

 sidered whether another and more resistant variety could not be 

 advantageously substituted. The probability is that as other species 

 became more numerous the borer would attack these in default of its 

 preferred variety, but perhaps not with the same intensity as in the 

 case of C. arabica. Coffea robusfa is as yet very scarce at Tonkin, so 

 that its possible immunity is not definitely established. In Java, 

 where X. javanicus. Cast. & Gory, occurs. C. arabica is the only variety 

 of coffee attacked. The Chari variety is very little grown at Tonkin, 

 but a larva of X. quadripes was found living in it. Coffea liberica, 

 which has been cultivated in Tonkin almost as long as C. arabica, has 

 not previously been known to be attacked, but the author found some 

 plants that had died of a root disease riddled by galleries of this beetle, 

 which had every appearance of having been made before the death of 

 the plants. The damage to this variety does not however appear 

 as marked as in the case of C. arabica. 



The times of emergence of the adults have been studied, and it is 

 hoped that eventually it will be possible to foresee the principal periods, 

 and to treat the plantations in time to prevent emergence and 

 consequently the infestation of fresh plants. Although emergence of 

 the adults occurs almost throughout the year, excepting during the 

 coldest weather, the numbers vary with the season. From January 

 to the end of March the adults, even if ready for emergence, do not 

 leave the galleries while the weather is cold ; they rest inactive until 

 there have been two or three sunny days before they come out. At 

 this time a careful watch should be kept for infested plants, though 

 frequently the signs of attack are not easily discernible. After the 

 beginning of April the infested trees are more in evidence and emergence 

 from these should be promptly prevented. In May, June and July 

 very few adults appear in the trunks, nymphs and larvae being chiefly 

 found. At the end of July, when the heavy summer rains come, 

 infested plants wilt suddenly and are easily recognised. Only larvae 

 are found in them at this time. In the author's opinion, the most 

 dangerous period at Cho-ganh in 1914 was August, September and 

 October, adults then being numerous on the stems. In November 

 and December, and through the other three ^^^nter months, emergence 

 is reduced to a minimum, and during this time it is only possible to 

 remove from time to time the affected plants that are dying or broken 



