130 



The Philippine Journal of Science 



IBIS 



feed extensively upon the tissues between the veins of the leaflets. 

 The injury has the appearance of a slight cut, but does not 

 entirely penetrate the leaf (Plate II, fig. 1). 



The injury done by the larva is greater than that of the 

 adult, as a single larva will excavate a place in the leaf from 

 12 to 16 millimeters long and 1.5 to 3 millimeters wide (Plate 

 II, fig. 2). The tissue affected soon dies and becomes brown, 

 and in badly infested areas the trees soon have the appearance 

 of unhealthy and half-dead palms. Where the palms are used 

 for ornamental purposes, the effect is very displeasing. The 

 palm itself is injured by the loss of these leaflets. 



Control. — The palm leaf -miner undoubtedly has many enemies, 

 both predacious and parasitic. Two species of hymenopterous 

 parasites of the family Chalcidae have been bred in great num- 

 bers, one from the egg (Plate I, fig. 9) and one from the larva 

 and pupa (Plate I, figs. 7 and 8). These have not yet been- 

 identified. It is probable that these parasites keep this beetle 

 in check, and were it not for them the leaf-miner would be a 

 most serious pest to the coconut industry. Observations have 

 shown that a little over 44 per cent of the larvae and pupae, and 

 an average of about 5 per cent of the eggs are parasitized by 

 chalcids. From these two parasites alone, the total percentage 

 of mortality is at least 50, and probably very much greater. 



The following table gives the results of the examination of 

 100 leaflets taken from infested palms: 



Table I. — Eggs, larvse, and pupm of Promecothera cumingii Baly taken 

 from 100 leaflets of the coconut pahn, August 3, 1910. 



Leaflets 

 examined. 



Eggs. 



Larvae and pupae. 



Alive. 



1 

 Dead. 



10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 



23 



41 

 38 

 25 

 27 

 29 

 30 

 21 

 24 

 13 



20 

 30 

 23 

 29 

 33 

 21 

 17 

 15 

 15 

 14 



18 

 11 

 23 

 22 

 35 

 16 

 12 

 6 

 11 

 22 



100 



271 



217 



176 



Remarks. — Leaves taken at random from different palms. No account 

 was kept of previous infected places, the only record was of places that 

 contained stages of the leaf-miner. Percentage of larva parasitized, 44.7. 

 Three leaves were found free from infestation. 





