76 



The Supplement to the Tropical Agriculturist 



BRASSOLIS ISTHMIA, A COCONUT 

 PEST IN PANAMA. 



A Lepidopterous Insect Highly Injurious to 



the Coconut. 



The attention of coconut growers in these 

 Islands is called to the following facts regarding 

 the above insect, from a report of Mr Henry F 

 Schultz, Horticulturist for the Canal Zone, 

 Isthmus of Panama:— 



Early in May, 1906, the majority of the coco- 

 nut trees in the neighbourhood of Ancon were 

 defoliated by the attacks of a carterpillar. Large 

 trees, which had been bearing crops for a num- 

 ber of years, stood without a particle of foliage 

 with their bare petioles and midribs resembling 

 skeletons. Some had to be cut down, but the 

 remainder recovered under the special care 

 given them. 



Later in the same year, about the middle of 

 September, the caterpillars again appeared, 

 although not in as large numbers as before, and 

 began to strip the trees anew. All coconut trees 

 were, therefore, sprayed with a strong solution 

 of arsenate of lead, a most tedious and trouble- 

 some, although very effective, method of fighting 

 these insects, in view of the height of the tree, 

 which were mostly from 30 to 35 feet, Although 

 torrential rains washed off the arsenate of lead 

 after a few weeks, it stayed on long enough to 

 kill all the insects on the trees which had re- 

 ceived treatment. 



This year the caterpillars made their appear- 

 ance again in May. Apparently this is the 

 time of year when the mature insects deposit 

 their eggs freely on all coconut trees in the 

 vicinity, for about the latter part of August 

 thousands of their larvae began to defoliate 

 these palms again and were evidently deter- 

 mined not to leave a single leaf on the trees. 

 However, one fact was noticed, viz., that the 

 larvfe feed only at night and that they retire 

 before the first rays of the sun into a tough web 

 spun with pinnae of the leaves, where frequently 

 as many as 700 to 800 crowd together in one 

 nest. The lower part of this, where the ends of 

 the pinnae meet, is left slightly open and the 

 nest presents the appearance of a long narrow 

 bag from 30 to 60 centimeters in length, accor- 

 ding to the number of insects it contains. 

 Frequently a tree will have two, three, or even 

 four of these nests and some were found where 

 the number of full-grown larvae were estimated 

 to be over 2,000. What even half of this 

 number can do to a full-grown tree if their 

 ravages are not speedily stopped can be 

 imagined, especially if the fact is kept in mind 

 that they attain the respectable size of 5 to 10 

 centimeters in length and have enormous 

 appetites like most caterpillars. 



A bearing coconut tree will thus bo stripped 

 of every inch of its foliage in a few nights and 

 receive such a severe check in its growth that 

 even with all due care in preventing the re- 

 appearance of the pest in following years, at 

 least two or three crops of nuts will be lost, and 



it is no rare occurrence that a tree dies outright 

 or becomes so weak that it cannot resist fungoid 

 and other diseases, and gradually perishes. 



After reaching maturity or when the supply 

 of food gives out, the larva passes into the chry- 

 salis stage, in which it remains twelve to sixteen 

 days, and this is the time when the larvae of an 

 apparently dipterous insect help in the exter- 

 mination of "Brassolis." It has been impossible 

 to determine whether the mature parasite de- 

 posits its eggs into the skin of the caterpillar or 

 into the chrysalis, or whether its ova are intro- 

 duced through the alimentary tract of the larvae 

 with its food. Dr. Darling, chief of the board 

 of health laboratory at Ancon, has examined 

 mature larvae of "Brassolis" under a high- 

 power microscope without finding any traces of 

 parasitic ©va in either the skin or the intestinal 

 ducts. However, as only a small number were 

 examined on account of lack of time, it is possi- 

 ble that the few specimens observed were not 

 infected with parasites. 



As the parasitic larvae are not protected with 

 a skin, which in the judgment of the writer 

 would be tough enough to withstand the gastric 

 juices of "Brassolis," the probability of cuta- 

 neous infection suggests itself. The destruction 

 of "Brassolis" through its parasites seems to 

 be rapid, though the actual time cannot be 

 given, as those in captivity seem to be free 

 from infection. 



As previously stated, the larvae feed only at 

 night and try to hide in their nests during the 

 day, but this hiding becomes in reality a means 

 of their being more easily detected and des- 

 troyed, for it is a great deal easier to cut down 

 these nests than to spray the trees. However, 

 this requires constant vigilance on the part of 

 the grower, as in the groves where the tree tops 

 frequently touch each other, the caterpillars can 

 crawl from tree to tree. 



The writer seems to believe that "Brassolis" 

 is one of the most formidable enemies of the 

 coconut grower if it is allowed to spread, and 

 that every possible attention should be given to 

 the immediate destruction of the larvae at their 

 first appearance. 



The "Brassolis isthmia'' has also been found 

 on the following palms : — "Martinezia caryo- 

 taefolia," "Acrocomia solerocarpa," "Oreodoxa 

 regia," "Oleracea," and two unidentified species 

 of "Thrinax." 



Any coconut growers who find that "Bras- 

 solis isthmia" has made its appearance in these 

 Islands are requested to advise the Bureau of 

 Agriculture at once, giving all the details pos- 

 sible with reference to its ravages in their 

 vicinity. — Philippine Agricultural Review, for 

 April, 1909. 



[Have any growers come across this pest, or 

 anything similar, in Ceylon estates? Perhaps 

 the Government Entomologist, Mr, Green, will 

 be able to say if the insect is known in Ceylon. 

 It is not mentioned in his list of pests of the 

 coconut palm given on p. 839 of the Tropical 

 Agriculturist for July, 1906.] 



