10 



about the centre. The sides are fringed with white lamellae, and the 

 ovisac is longitudinally grooved. 



Distribution. — Common in Jamaica. Found also in Trinidad, British 

 Guiana, and Mexico ; likewise in Ceylon, and on hothouse plants in 

 England and the United States. 



Food-plants. — Very various, Strobilanthes, potato, Citrus trees, verbe- 

 na, mint, Chrysanthemum, violets, Myosotis, Lantana, Eupatorium, 

 Coleus, &c. 



Destructiveness. — Avery pernicious species in hothouses both in Eng- 

 land and the United States, especially upon Coleus Out-of-doors in 

 warm countries it is also quite a pest, notably on Citrus-trees in Trinidad 

 (Hart) and Mexico (Townsend.) 



Remarks. — A detailed account of this insect, by Mr. C. P. Lounsbury, 

 will be found in the 32nd Annual Report of the Massachusetts Agri- 

 cultural College. 



(51.) Orthezia prcelonga, Douglas. (The Horned Lamellated scale.) 



Diagnosis. — The back is almost entirely covered by white secretion, 

 two thick processes of which project over the head, like horns. The 

 ovisac is longitudinally ribbed or grooved. 



Distribution. — British Guiana, Trinidad, and Jamaica. 



Food-plants. — Capsicum, Sanchezia, and Croton. 



Destructiveness. — Mr. Hart sends it from the Trinidad Botanic Gar- 

 dens in enormous numbers on Croton ; it must be very troublesome 

 when so abundant. 



INSECTICIDES.* 



By J. E. Duerden, Curator of Museum, Jamaica Institute. 

 The Arsenites — Paris Green and London Purple. 

 There is little difference in these two insecticides, the former being 

 arsenite of copper and the latter arsenite of lime. The London purple 

 is lighter in weight, mixes more easily with water, but burns the foliage 

 more readily than Paris Green. 



A. As a Du4: — The Arsenites are often used in the dry form with 

 lime, plaster, or flour. The best rule as to the proportion in which to use 

 them is to combine them so that only a very faint green or purple tint will 

 be seen in the mixture. This makes a proportion of 1 part of arsinite 

 to 100 or 150 of powder. 



B. As a Spray : — Take one pound of Paris Green or London Pur- 

 ple to 200 gallons of water; or 3 ounces of either to every 40 gallon barrel, 

 is not apt to burn the foliage and proves effectual on leaf- eating insects. 

 Occasionally unaccountable injury will occur, and it is always safest to 

 use a little milk of lime in the spraying mixture A pound or two of 

 the lime, freshly slaked, to each barrel of the mixture is sufficient. It 

 should be considerably diluted and allowed to settle, or else strained into 

 the barrel through some coarse cloth, before using, or the dirt and im- 

 purities will clog the pump and nozzle in spraying. This lime forms a 

 chemical combination with the soluble arsenic and makes it insoluble. 

 In this condition it kills insects as readily as the soiuole arsenic, but 

 does not prove harmful to plant life. 



* For many of these notes and formulae I am indebted to Bulletin 121, of the 

 Michigan Agricultural Experiment Station. 



