66 EXPERIMENT STATION RECORD. [Vol.38 



Following a historical review of the literature dealing with quassia and quassiin, 

 and with quassia extract as an insecticide, the authors report investigations 

 conducted with a view to determining (1) the efficiency of various extracts of 

 quassia wood, and (2) the pharmacological effects of these extracts upon 

 insects. 



" The exhalations alone from the quassiin powder killed aphids, but the 

 exhalations from quassia chips, quassia powder, and those from solutions con- 

 taining quassiin extract and quassia extract were ineffective. Quassia powder 

 dusted upon insects is inefEective, while quassiin powder is quite effective, indi- 

 cating that the exhalations pass into the respiratory system and that they then 

 affect the nervous system. The minutest particles of either powder are suffi- 

 ciently small to pass into the spiracles, but they do not cause death by closing 

 the entrances of the tracheae. 



" Quassia and quassiin spray solutions, not containing soap, kill aphids when 

 applied sufficiently strong. By the process of elimination it is concluded that 

 death occurs as a result of some of the fine spray being breathed into the 

 respiratory system while the aphids are being sprayed. The greater effective- 

 ness of solutions containing soap is due to the weaker surface tensfon of such 

 solutions, which pass freely through the spiracles and finally reach the nervous 

 tissue, where they kill by slowly affecting the nerve cells." 



It was found that unlike nicotin, which acts quickly and causes pronounced 

 symptoms, quassiin acts very slowly and causes but few symptoms and these 

 are never pronounced. It is concluded that owing to the poor insecticidal 

 properties of quassiin, quassia extract can never become a general insecticide 

 for all aphids. Although the amount of extract to be used can be sufficiently 

 increased so that the spray solution will perhaps be efficient on any particular 

 aphid, in most cases the expense will prohibit its use. The most effective 

 formula used was prepared by soaking 22 lbs. of quassia chips in 100 gal. of fish- 

 oil solution (1.6 lbs. of soap to 100 gal. of water) for 24 hours. 



A list of 48 references to the literature is included. 



How to test for the presence of nicotin on sprayed plants, V. I. Safbo 

 (Jour. Econ. Ent., 10 (1917), No. 5, pp. 459-461). — The test recommended by 

 the author is made by thoroughly rinsing a number of sprayed leaves with a 

 minimum amount of distilled water, then filtering, and acidulating the filtrate 

 with a few drops of hydrochloric acid. If a precipitate is formed at this point 

 the filtration should be repeated and to the resulting filtrate several drops of 1 

 per cent silicotungstic acid should be added, when a white cloud will denote 

 the presence of nicotin. 



" This test has been applied successfully to aqueous solutions of ' free ' nico- 

 tin, nicotin sulphate solutions, nicotin soap solutions, nicotin-arsenate of lead, 

 and nicotin Bordeaux. It has not been found effective in testing nicotin 

 lime-sulphur, as the presence of colloidal sulphur derived from the polysulphids 

 seems to interfere with the test." 



Rules and regulations for carrying out the provisions of the Insecticide 

 Act of 1910 [U. S. Dept. Agr., Office Sec. Circ. 34, 2. rev. {1911), pp. 15).— 

 The text of the Insecticide Act of 1910 (E. S. R., 24, p. 361) and the rules 

 and regulations, as amended to August 3, 1917, are here given. 



Gomphus parvidens, a new species of dragon fly from Maryland, Bertha 

 P. CuBKiE (Proc. V. S. Nat. Mus., 53 (1917), pp. 223-226, pis. 2). 



An asymmetrical bird louse found on three different species of troupials, 

 J. H. Paine (Proc. V. S. Nat. Mus., 53 (1917), pp. 231, 232, pi. 1). 



The European earwig and its control, D. W. Jones (V. S. Dept. Agr. Bui. 

 566 (1917), pp. 12, fig%. 8). — This is a report of investigations made of Forficula 



