537 



measures attempted in the Dutch East Indies are mentioned. Experi- 

 ments made with an 8 per cent, sokition of carbolineum, which does 

 not injure Liberian coffee if carefully a])plied, proved satisfactory. 

 This can also be used on Citrus with a better result than petroleum 

 enuilsion. Thorough remedial measures include the destruction of the 

 ants ; nests in the ground may be treated ^^■ith carbon bisulphide. 



Dolichoderus bidens causes such inconvenience to workers among the 

 coUee that picking is done hastily and unsatisfactorily. Experiments 

 were made with poisons, including calomel and the California ant- 

 poison, and with various sprays, including nicotine sulphate, carboli- 

 neum, carbolic acid and j)liytophiline. The last two gave the best 

 results. The high cost of phytophiline precludes its use, and carbolic 

 enuilsion is advised. To prepare this, 5 lb., of soap is dissolved in 4| 

 gals. of water at boiling point, and then |gal. of crude carbolic is verj 

 thoroughly stirred in. Stirring may be avoided by keeping the 

 mixture boiling for 20 minutes. The emulsion is diluted with 10 parts 

 of water for use. 



The coffee thrips, Heliothrips haonorrhoididis, Bch., also occurs on 

 cacao, Citrus, and other cultivated plants, and on the wild plants, 

 Coccoloba latifoUa, Triplaris surinamensis, and Hura crepitans. It does 

 no injury to coffee, though quite as abundant on it as the cacao thrips, 

 H. rubrocinctus, Giard, is on cacao, because the coffee leaves do not drop 

 as a result of the infestation. It should be noted that H. rubrocinctus 

 is harmless on its other food-plants, Bixa orellana, Terminalia calappa, 

 and Jambosa vulgaris. Though H. rubrocinctus also infests coffee, it 

 does not feed on it, and cannot be reckoned as a coffee ]jest. 



VAN Heurn (F. C). Verslag van den Directeur 1 Juli 1918-30 Juni 



1919. Meded. Algem. Proefst. A.V.R.O.S., Mcdan, Algem. Ser. 

 no. 7, 1919, 66 pp., 1 plate. [Received 22nd October 1920.] 



This report is issued by the acting director in Dr. Kutger's absence. 

 A number of notes are given from the report of the Entomologist, 

 Mr. J. B. Corporaal. 



Hevea borers included a Bostrychid, three species belonging to the 

 genus PraonetJia, and an Anthribid, as well as those mentioned in the 

 previous report [R.A.E., A, vii, 64] . Mites still occur, but no serious 

 complaint was made. A similar report of Psychid infestation was 

 received as in the preceding year, and Psyche {AcanthopsycJie) snelleni, 

 Heyl., was probably again the cause. Coptotcrmes gestroi, Wasm., 

 and an ant, probably Solenopsis geminata, F., also injured Hevea ; 

 the last causing damage similar to that of P. snelleni . 



Tea remained unattacked by Helopeltis. The Lygaeid bug reported 

 in the previous year is closely allied to Colobathristes saccharicida, 

 Karsch. C. saccharicida itself was sent in on one occasion. Other 

 tea pests were Lepidiota sp. ; the hovers, . Zeuzer a cqffeae, Nietn., 

 and Xyleborus fornicatus, Eich. ; a Notodontid, Stauropus alternus ; 

 and Limacodid caterpillars. The latter are sometimes covered with 

 urticating hairs that inconvenience the workpeople. On one estate 

 Abizzia, used as a shade for tea, was very severely infested by Psyche 

 snelleni, and the tea was in\'^5lved to some extent. 



