514 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



to 1904. The late Dr. C. W. Hooker began an extended study of 

 coffee insects and this article is a summary of his results and of the 

 writer's observations up to date. 



Coffee Leaf Miner 



The most generally distributed pest of coffee is the leaf-miner 

 ("minador de la hoja"), Leucoptera coffeella Stain. This insect occurs 

 throughout the world in almost every country in which coffee is grown, 

 and was probably brought to Porto Rico when the first coffee plants 

 were introduced. Coffee is the only known host of this insect. 



The adult moth is a small, silvery white insect measuring about 

 2 mm. in length. It is a swift flier, hiding under leaves during the 

 daytime and venturing forth only at night. The length of adult life 

 varies from 1 to 4 days. 



The silvery white, fiat, oval egg measures about .3 mm. by .2 mm. 

 and has a boat-shaped depression which includes the greater part of 

 its upper surface. It is usually laid on the upper leaf surface and 

 hatches in from 3 to 8 days (average for 107 eggs, 4.7 days) . The larva 

 mines the parenchymatous tissue and seriously reduces the functioning 

 area of the leaf, especially when the main veins are crossed. The larval 

 period varies from 7 to 15 days (average for 38 larvse, 11.4 days). 

 The fully grown larva emerges through a hole in the upper surface of 

 the mine, and after wandering over the leaf a few hours, spins its co- 

 coon, usually on the underside of the leaf. From 3 to 9 days are spent 

 in the pupa (20G pup^ averaged 5.3 days). 



Artificial control of the leaf miner has so far been impractical. 

 Nicotine sulphate sprays were partially effective for the larvse, but 

 failed to kill the eggs. Fertilizing may be a means of remedying the 

 damage done by the miner, for with a stimulation of leaf growth the 

 percentage of leaf area, not functioning because of the miner, will be 

 lowered, for a time at least. The expense of fertilizers in Porto Rico, 

 together with the low market value of coffee, makes fertilizing here a 

 doubtful proposition from an economic viewpoint. 



Some varieties of coffee seem to be practically immune to miner 

 injury due to the thickness of their leaves; among these are the Liberian 

 coffee and several other species belonging to the same group. Their 

 product is considered inferior in quality to the common Porto Rican 

 coffee, which is the typical Coffea arabica. 



There are two fairly effective Chalcids parasitic on the miner in its 

 larval stages. These are Zagrammosoma multilineata Ash. and Chryso- 

 charis livida Ash. The latter is the more abundant of the two and at 

 times is responsible for at least 30 per cent mortality. 



