ECONOMIC ZOOLOGY ENTOMOLOGY. 457 



The authors prepared a series of solutions containing various quantities of 

 copper sulphate with an excess of lime. After being kept at a constant tem- 

 perature for several weeks the solutions were allowetl to stand for several days 

 to allow the subsidence of all the precipitate and both the solutions and precipi- 

 tate examined. The solutions were found to contain lime and sulphiiric acid 

 (SO3) without any trace of copper, while the precipitate in every case showed 

 the presence of gypsum and a second wliite solid which was believed to be 

 calcium hydroxid. The copper hydroxids in the precipitate are believed to be 

 copi>er ox ids in different stages of hydration, differing somewhat in their 

 characteristics. 



The authors state that in the preparation of Boi'deaux mixture a great 

 excess of lime is added, and consequently the solution will contain calcium oxid 

 and sulphuric acid while the precipitate consists of lime, gypsum, and blue 

 copper hydroxid. As the solution fails to show the presence of copper by the 

 conunon tests it seems that the beneticial effect obtained from the use of Boi*- 

 deaux mixture must be attributed to the blue copper hydroxid or to the minute 

 quantities of copper in solution. 



A new copper salt and its use as a fungicide, P. Malvezin {Bill. Soc. Chim. 

 France, 4. se?:, 5 (1909), No. 23, pp. 1096-1098).— A description is given of a 

 copi>er salt which is said to be a combination of formalin, liydi'ate or hydro- 

 carbonate of copper, and sulphuric anhydrid, and to be dimethanal-disulphite 

 of copper. It is thought to have active fungicidal properties, and would prob- 

 ably be valuable for use in combating diseases of plants. 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



Prairie dog situation, T. H. Scheffeb (Kanms »s7r<. Ciic. .}, pp. 7, fig. 1). — 

 This circular reviews the work carried on in Kansas against the prairie dog 

 and gives a detailed account of the station's method of poisoning. 



The poison mixture is prepared and used as follows: One oz. of green coffee 

 berries is mixed with the white of 1 egg and allowed to stand at least 14 hours. 

 One oz. of strychnin is dissolveil in ^ i)t. of boiling water. One oz. potassium 

 cyanid is dissolved in \ pt. of hot water and allowed to cool. A little warm 

 water is added to the mixture of coffee and eggs and mixed with the potassium 

 cyanid. This mixture is then strained through a coarse sieve into the mixing 

 vessel and 1 pt. of sirup added. The hot solution of strychnin is next mixed 

 with 11 oz. of alcohol and added to the other mixture. After thoroughly shak- 

 ing and stirring the contents of a quart can of the mixture it is poured over 

 A bu. of clean wheat or Kafir corn and stirred until every part is thoroughly 

 wet with the poison, then 2 or 3 lbs. of fine corn meal stirred in to take up 

 the extra moisture. The mixture is allowed to stand over night and put out 

 early the next morning if pleasant, half a tablespoonful or less of the bait 

 being placed in 2 or 3 little bunches at the outside of each burrow occupied 

 by prairie dogs. Only occupied burrows should be poisoned. A half bushel 

 of grain should poison from 500 to 600 boles. 



In a recent survey of the former extensive prairie dog territory of western 

 Kansas lying between the Union Pacific Railroad on the north and the Santa Fe 

 on the south it was found that over most of this region the prairie dog is no 

 longer of economic imp(U'tance. In several other sections, however, particularly 

 along the flats and breaks adjacent to the Smoky Hill River, the prairie dog has 

 yielded ground but slowly and still constitutes a serious menace to stock graz- 

 ing and diy-land farming. 



.31 1 2.5— No. 5—10 5 



