TRANSACTIONS OF SECTION D. 767 



6. On Icerya Purcbasi, an insect injurious to Fruit Trees. 

 By Professor Rilet. 



The species is tlie most polypliagous of coccids, living on a great variety of 

 plants, and thriving particularly on acacia, lime, lemon, orange, quince, pome- 

 granate, and walnut. It is capable of motion at all stages of development after 

 hatching, and can survive without food for a long period. These characteristics 

 have rendered it the mo.*t grievous enemy which the fruit-grower has to contend 

 with in Australia, New Zealand, South Africa, and California. It is believed to 

 have originated in Australia, and to have been introduced into other parts of the 

 world upon living plants. But in endeavouring to get accurate data for this belief 

 I have been led to question the specific value of Icerya Turchasi, Maskell, as com- 

 pared with Icerya sacchari, Signoret. This last infests sugar-cane in the islands of 

 Bourbon and Mauritius, and, on the hypothesis that PurcJiasi is a synonym of it, 

 the wide distribution of the pest through the sugar trade becomes at once intelli- 

 gible, as it is a common practice in the Pacific islands to insert a piece or pieces 

 of the cane in the hogshead or other packages for the purpose of facilitating the 

 drainage of sj'rup; that is an accompaniment of the unrefined sugars produced there. 



Thus the question of synonymy bears directly on the original source of this 

 pest, and this is important to us practically in any study of the natural enemies of 

 the species with a view to their artificial introduction into those countries which 

 Icerya has invaded without its natural checks. 



This Icerya, on account of the protection offered by the fluted waxy ovisac, and 

 of its other characteristics already mentioned, is one of the most difficult of all 

 insects to control, as few insecticides will reach the eggs. 



In my official paper ' will be found details of experiments whereby the diffi- 

 culties have been surmounted in California by judicious spraying of kerosene 

 emulsions and resin soaps, as well as by a combination of cyanhydric gas evolved 

 from potrtssic cyanide, and carbonic gas evolved from sodic bicarbonate, used under 

 a portable tent. 



7. On a Luminous Oligoohcete. By Professor Allen Haeker, F.L.S. 



The author described a remarkable phenomenon of luminosity or phosphores- 

 cence exhibited on a large scale on a peaty moor in Northumberland at an elevation 

 of 600 feet. The imprint of recent footmarks on the peaty ground shone with a 

 brilliance recalling similar effects on sea-shores described by numerous authors 

 while the feet of the horses of a riding party galloping across the wet peaty soil 

 threw off" the luminous mud in what appeared to be showers of white glowino- fire. 

 An examination of the peaty soil showed the presence of innumerable small Oli- 

 gochsete worms, which by a variety of experiments, detailed by the author, were 

 proved to be the producers of the luminosity. In a darkened room a sino-le worm 

 on being gently rubbed glowed like a fine streak of phosphorus. The worm is a 

 small Enchytrseus, but will be fully described. 



8. On the Hessian Fly, or American Wheat-midge, Cecidomyia destructor 

 Say, and its appearance in Britain. By Professor W. Fream B Sc 

 F.L.S. , F.G.S. 



The Hessian fly was discovered in Britain in barlt^j-fields near Hertford in 

 July 1886, previous to which date there is no record of its occurrence in this 

 country. During the present summer it has been traced over the greater part of 

 England and Scotland, and the author found it on July 14 in fields of wheat and 

 barley on the borders of South \\'ilts and South Hants. 



The pest is a true two-winged fly (order, Bipta-a ; family, Cecidomyiidce), 

 and its habits and life-history are described. As a crop scourge it has proved 

 most disastrous in the United States, where only tlie Rocky Mountain locust 



' Beport of the Entomologists, U.S. D/'jiartment of Agriculture, for 1886 • Bull. 

 15 Div. of Entomology, U.S. Dept. Agr. 



