360 



THE AGRICULTURAL NEWS. 



November 7, 1914. 



INSECT NOTES. 



NAPHTHALENE AS AN INSECTICIDE. 



Xaphthalent.' is one of the liy-pnxlucts olitaiiied in the 

 -^listillation of coal tar. It has been long known as an insect 

 vepellant, and some of its uses are very familiar to nearly 

 everyone. It may be of interest, however, to bring together 

 a brief account of several ditterent ways in which it may be 

 employed. 



The Ijest known use for naphthalene is for the protection 

 of stored clothing, books, insect collections, and museum 

 .specimens. Clothing such as woollen garments, feathers, and 

 furs are protected from moths and beetles by being packed in 

 tight boxes, or securely wrapped in parcels covered with paper, 

 cotton, or linen cloth, iloth Ijalls, naphthalene flakes or 

 crystals, freely used in such bo.xes or parcels, give good 

 protection, the insects lieing reyielled by the smell of the 

 na])hthalene. 



1 looks which are kept in closed bookcases may be 

 protected to a large extent by scattering flaked naphthalene 

 freely on the shehes, behind the books, and on and between 

 the liooks themselves. 



Insect collections should be kept in tight boxes; 

 naphtlialene flakes in the bottom of the boxes, or moth 

 balls on pins in the corners of each box, will keep out 

 insects and mites which are destructive to stored insects. 

 iloth balls can be fixed on pins (juite easily. An ordinary 

 pin heated in the flame of a lamp or candle can be forced 

 through the moth ball by means of pliers or forceps, and 

 when it cools tlie naphthalene will set firmly round it. 



As a remedy to be used against cockroaches, naphthalene 

 is not so well known. In the A<i>icultural News for Sep- 

 tember 27, U)1.S (Vol. XII, p. 314) a note appeared giving 

 an account of good results obtained from the use of a mixture 

 of equal quantities of naphthalene (finely pmvdered) and 

 I)oracic acid. This mixture was plentifully sprinkled in 

 places frequented by cockroaches. The insects were greatly 

 reduced in numbers after the second application, which was 

 made after an interval of two weeks. 



The use of naphthalene for freeing a house from an 

 infestation of fleas was noted in the Agricultural Newi for 

 May '.), 1914 (Vol. XIII, p. 154). In this case a 'new hou.se 

 was seriously infested before being inhabited. Naphthalene 

 to a depth of 2 or -3 inches was put on the floors of one or 

 two rooms, and after twenty-four hours was swept up and 

 put into the other rooms and passages of the house, until all 

 were so treated. The fleas were all killed out. 



Naphthalene is also very useful as a dry bath for dogs 

 .-and cats infested with fleas. The insecticide in a very finely 

 pondered condition, or in the form of flakes, is rubbeil into 

 the coats of the dogs or cats, and the fleas aie rapidly driven 

 ■out by it. They fall to the ground in a stupefied condition; 

 if the operation is carried on over a sheet of cloth or 

 strong paper, and the naphthalene is freely used, the fleas are 

 killed by continued contact with it, and it can be taken up 

 and used over and over again. 



The naphthalene has no disagreeable or deleterious ettect 

 oTi the animals, and does not leave any disagreeable smell in 

 their coats after the application. Dogs treated with naph- 

 thalene in this way remain much freer from fleas than when 

 the control of these insects depends on ordinary washing and 

 "* |)icking'. 



Naphthalene has recently been used with success in the 

 prevention of insect attack on stored grain. In India (see 

 Agricultural Journal of India for .January 1914) an inter- 

 esting series of experiments was published, which showed 

 Ihat this substance gave a thorough protection to stored 



maize over a period oi thirteen months. The grain was' 

 placed in cylindrical bins, about 6 feet deep by .S feet 

 in diameter, each bin holding about 40 bushels. The 

 charge used was 1 D). per bin, divided into four lots of 

 \-%. each. These were enclosed in bags made of cloth 

 with open texture, and were placed at e(|ual distances from 

 the liottom to the top. The bins were tight, and were 

 tightly covered. At the conclusion of the trials it was found 

 that about one-half of the naphthalene still remained in the 

 bags. 



The results were very satisfactory, and indicate that 

 )iaphthalene used in this way provides ett'ective protection for 

 stored grain. 



Naphthalene is very useful in the preparation of emul- 

 sions of oil in soap solutions, in making spray mixtures for 

 the control of scale insects. 



The peculiar property possessed by this material of 

 bringing abciut an easy and perfect cond^ination of oil and 

 soap solutions was discovered by Mr. H. H. Cousins some 

 years ago when connected with the Eastern Agricultural 

 College at Wye, England. Mr. Cousins prepared a mixture 

 to which he gave the name Paranaph, which was composed 

 of soft soap, naphthalene and kero.sene oil. This was success- 

 fully used against' insect pests on plants; and later, in 

 .Jamaica, ilr. Cousins applied it also to the destruction of 

 ticks on cattle, fleas on dogs, and other similar purposes. 



Mr. H. Maxwell-Lefroy prepared a mixture of whale-oil 

 soap and Barbados crude oil ( West Indian Bulletin, Vol. Ill, 

 p. 319), applying Mr. Cousins's principle of using naphthalene 

 to bring about the combination of the oil and soap. More 

 recently, Mr. J. C. Moore of St. Lucia has applied the same 

 methods to the preparation called Scalo, which is a mixture 

 of whale oil soap, kerosene and naphthalene. (See Agricul- 

 tural A" /'■.». Vol. XIII, p. 282.) 



Naphthalene is sold in Barbados at retail, at the rate of 

 \s. per lb., and in quantity at 7 id. per lb. In England and the 

 United States the price is of course lower, but even at the 

 rate of 1\d. per lb., it is a very cheap material to u.se for the 

 several purposes mentioned above. It possesses advantages 

 over certain other substances for which it might be used as 

 a substitute, since it is ea.sy to handle, clean, and not 

 dangerovis either from being poisonous or highly inflammable 

 or explosive in character. 



Onion Growing in the Virgin Islands.— A 



cojjy has been receixed of a circular entitled The Onion 

 Industry in the Virgin Islands, which has recently been 

 issued from the E\pei-iment Station, Tortola. This leaflet 

 has reference to the present conditions of onion growing in 

 the Presidency, where seedlings are raised on a considerable 

 scale by the Agricultural Department, and sold to the 

 peasantry. The local market for the onions so produced is 

 either Tortola, or St. Thomas, the neighbouring Danish 

 colony. The circular states that most of the onions con- 

 sumed in the Viigin Islands are imported. This would .seem 

 unneces.sary in view of the suitability of Tortola for onion 

 growing, and the i^ttbrts made by the Agricultural Depart- 

 ment to encoiu'age this cultivation. 



The circular under consideration provides practical 

 information ccmceining soil requirements, cultivation, trans- 

 planting, su'bseiiuenl treatment of plants, and advice on 

 onion growing in relation to local conditions. The circular 

 would appear lo b.- deficient in respect of information on the 

 sowing of se."di5, and the packing and marketing of onion.s. 

 It may nevertheless be considered likely to assist and 

 encourage those cultivators who are intent upon taking up 

 what promises to be a very profitable industry. 



