REPORT OF THE ENTOMOLOGIST. 



371 



pliances the dry powder may be sifted or blown upon the foliage when 

 wet with dew or rain. A little wheat-tlour added to the powder would 

 increase its adhesiveness. 



The pharmaceutical preparation known as milk of sulphur (precipi- 

 tated), although a much more finely divided powder, proves milder in 

 its effect upon the mites, and its cost wtfl prevent its extensive use. 



EXPERIMENTS. 



(1.) A small seedling orange infested with Bust-mite was covered 

 with a nail-keg and fumigated for ten minutes by burning one ounce 

 of sulphur under the keg. All the mites were destroyed, but the eggs 

 remained alive ten days, and finally dried up with the leaves of the 

 plant, which was entirely killed. 



(2.) Flowers of sulphur dusted over infested leaves through a loosely 

 woven cloth. Free mites all dead in twenty-four hours. Molting 

 young all dead in three or four days. Eggs not killed in nine days, but 

 young mites killed soon after hatching. 



(3.) Experiment No. 2 repeated in the open air, and leaves allowed to 

 remain on the tree. Heavy rains on the second day did not remove all 

 the sulphur. Eesults the same as in No. 2. Mites all killed. Eggs 

 not killed. 



(4.) Milk of sulphur dusted upon the leaves through muslin. Effect 

 less powerful than in Nos. 2 and o, but mites in the end all killed. 

 Eggs not killed. 



(5.) Milk of sulphur ; two ounces by measure, of the powder suspended 

 in one gallon water. Leaves dipped in the liquid, when dijy were lightly 

 coated with grains of sulphur. Adult mites dead on the second day. 

 Some molting mites and numerous eggs alive on the second day. 



(G.) Leaf with mites confined in a tight box with another leaf on which 

 sulphur had been dusted. No effect after twenty-four hours. On the 

 third day, however, only one adult mite appeared to be alive. In six 

 days all the mites were plainly killed. Eggs not killed. 



This experiment was repeated with sulphur scattered in the bot- 

 tom of the box, and precautions taken to prevent its contact with t lie 

 mites. Eesults precisely the same as before. 



Note. — By confinement in very tight metal boxes, mites may be kept 

 alive between one and two weeks, or until the leaves dry up or mold. 

 The destruction of the mites in this experiment was therefore due en- 

 tirely to the slow volatilization of the sulphur. 



(7.) Sulphuretted hydrogen. Leaves dipped in water strongly im- 

 pregnated with the gas. In twenty-four hours all adult mites were 

 dead or dying. In thirty-six hours all free mites were dead. In the 

 same time 40 to 50 per cent, of the molting mites died. On the third 

 day many molting mites remained alive. Eggs not killed. 



The above solution of sulphuretted hydrogen (sulphur water) was 

 prepared by passing through two gallons of water, the gas given off by 

 three ounces of sulphuret of iron, treated with dilute sulphuric acid. 



The remarkable results obtained with sulphur in these experiments, 

 and especially the effect upon the adult mites of the gas in solution, sug- 

 gests the use of water from the sulphur springs which abound in various 

 parts of Florida. Although it cannot be supposed that these natural 

 waters contain a sufficiently high percentage of the mineral to render 

 them powerful insecticides, their value . cannot be determined without 

 trial. Persistent applications may suffice to ultimately exterminate the 

 Bust-mite or cause its disappearance from the trees. In view of its 



