6 REPORT ON INJURIOUS INSECTS FOR 1904. 



In either case the soil so treated should be allowed to remain 

 for six or seven weeks before being used again. 



CRUSTACEA 



WO OBLIGE. 



Porcellio scaber, Linn., and Oniscus asellus, Linn. 



Various species of woodlice have proved troublesome in 

 gardens, conservatories, etc., during the past year, but none more 

 so than; these two species. One correspondent reports that they 

 eat thetdeveloping fronds of ferns, another complains of them 

 biting the new branches of Stonecrop and Selaginella. They are 

 particularly fond of such plants as the Stonecrop (Sedium acre), as 

 it affords them shelter and at the same time moisture, which 

 latter is very important. 



Although in the popular mind these animals are generally 

 regarded as insects, they are structurally very distinct from them, 

 and belong to a Class of animals the Crustacea which includes 

 the crab, crayfish, and shrimp. 



PREVENTIVE AND REMEDIAL MEASURES. 



Trapping is one of the most successful measures I know of, 

 and for this purpose little heaps of wet grass or leaves, wet wooden 

 boards 12 by 6 inches, or plant pots filled with wet grass, should 

 be left on the floor of the conservatory or potting house over 

 night and examined next morning. 



THE BLACK-CURRANT GALL-MITE. 



Eriophyes ribis (Nalepa). 



During the past year a Report (0 has been issued suggesting 

 new remedial measures for this insidious pest, from which the 

 following is an extract : 



Spray fluids, The only time sprayfluids can be used to any 

 purpose is during the season of migration. The extensive ex- 

 periments carried out at Woburn < 2 ) with petroleum, calcium 

 sulphide, carbolic acid, antinonnin, etc., where 30 bushels in a 

 double row were treated once a month for each experiment, 

 proved ineffective, as did also undiluted methylated spirits, 

 naptha, a saturated solution of naphthalene in naptha, a 2 per 

 cent., 0.5 and o.i solution of formalin, turpentine, undiluted 

 petroleum, petroleum emulsion : i part of petroleum, 5 parts 

 of water, and 2 of soft soap,, applied once a month with a brush. 



I have made experiments with various arsenical fluids, 

 bruised hellebore, lime, sulphur and lime, &c., &c., and while 

 many have considerably reduced the numbers of the mites, I 

 have to confess that their practical value is very small. 



1. Rpts. on Economic Zool., No. i, 1904. 



2. Second Rpt. Woburn Exp. Fruit Farm, 1900, pp. 13-20. 



