6 



"While blaming the Coccidae for their injuries, it must be remembered that certain species are 

 very useful. We have one such in Jamaica, the Cochineal Insect (Coccus cacti), which abounds on the 

 Opuntia in the Parade Gardens, Kingston. 



Methods of Destroying them. 



Excellent methods of destroying scale-insects have been devised by the Entomologists of the U. S. 

 Department of Agriculture, and very full details of their experiments have been published. The most 

 useful remedy for ordinary purposes is the Kerosene Emulsion, made according to the formula 

 originated by Mr. H. G. Hubbard, and usually recommended by Prof. Riley, as follows: — 

 "KeroseneOil ... ... ... 2 gallons = 67 per cent.. 



Common Soap, or Whale-Oil Soap ... ... \ pound ) _ er QQn ^ 



Water ... ... ... 1 gallon J ~~ ?^L» C t n J 



Dissolve the soap in the water by heating, and add the solution, boiling hot, to the kerosene and churn 

 the mixture by means of a force-pump and spray-nozzle for five minutes. The emulsion, if perfect, 

 forms a cream which thickens on cooling and should adhere without oiliness to the surface of glass. 

 Dilute, before usiug, one part of the emulsion with nine parts of cold water. The above formula 

 makes 3 gallons of emulsion, and when diluted gives 30 gallons of wash." 



This is applied by means of a pump and nozzle, and the more finely it can be sprayed on the 

 better. Many different modifications of both pump and nozzle have been brought into use in the 

 United States, and are discussed by Prof. Riley in Dr. Packard's work on Forest Insects (5th Report 

 U. S. Ent. Commission). The best known nozzle is that called the Riley or Cyclone nozzle ; and a 

 modification of it, the Vermorel nozzle, has proved successful in France. The Nixon or Climax nozzle 

 is also said to be very satisfactory, especially where considerable force is required. 



Resin washes have been used extensively in California against scale- insects, as also various com- 

 pounds of kerosene with resin, &c. In adopting these methods for Jamaica, it must always be remem- 

 bered, that some remedies which may serve excellently in temperate regions, at times when there is no 

 fresh foliage on the trees or they are bare of leaves, might be extremely injurious in a tropical country, 

 where there is always a quantity of foliage liable to injury. It appears to be the custom in California 

 to apply the resin washes principally in the late summer and autumn; and no doubt we might do well 

 in Jamaica, by selecting that time for spraying when the affected tree has fruited, and is under- 

 going a period of more or less rest. * The extent of this resting period in the tropics varies 

 very much among the different species ; thus, the Poinciana regia, as every one in Kingston 

 has the opportunity to observe, has a very distinct interval between the successive flowering- 

 periods, while the orange of course exhibits flowers and fruit at once. There can be little 

 doubt I suppose that every species of tree has some period when a wash could be safely applied,, 

 which would at another time prove injurious. 



Prof. Riley writes (5th Report U. S. Ent. Com., p. 37) regarding the Resin washes : — 



" Mr. Koebele had good success with the resin compound prepared as follows : Dissolve 3 pounds 

 of sal -soda and 4 pounds of resin in three pints of water above fire; when properly dissolved, add 

 water slowly, while boiling, to make 36 pints of compound. A very strong solution of this was used 

 on pear trees without injury to the foliage, the solution consisting of 3 pints of the compound to 4 of 

 water. Numerous successful experiments were made with one part of the compound and 8 parts of 

 water, and this strength for most purposes will be sufficient. 



"Mr. Coquillett has found the following to be an excellent formula for the preparation of thia 

 compound — 



Caustic soda ... ... 1 pound. 



Resin ... ... 8 pounds. 



Water to make ... ... 32 gallons. 



" Dissolve by boiling the caustic soda in a gallon of water ; add the resin to one half the soda 

 solution and dissolve it by boiling ; add the remainder of the soda solution and boil over a hot fire, 

 stirring constantly. When sufficiently cooked it will assimilate with water like milk, which it much 

 resembles. Add water and strain through a fine sieve. 



" An emulsion of kerosene with resin compound was satisfactorily accomplished by taking equal 

 parts of both substances and working them together for two minutes with a pump. The emulsion is 

 not so stable as the emulsion with soap, but it is eminently effective against scale-insects and aphides. 

 At my suggestion the addition of arsenic in the proportion of 1 pound to from 75 to 300 gallons of 

 the resin, or resin and kerosene wash, was made, and this addition was found to greatly increase the 

 efficiency of these insecticides." 



Mr. Coquillett's resin wash has been used on Orange and Lemon trees without causing any 

 injury to foliage or fruit. It proves fatal to a large proportion of the black scales, (Bernardia olece), 

 but probably some always survive, muking it expedient to apply the remedy more than once. The 

 black scale, however, seems exceptionally hard to exterminate, being well-protected by its structure 

 and very prolific, and the kerosene emulsion is also reported to have failed to destroy it. Mr. Ehwood 

 Cooper, of Santa Barbara, California, applies the kerosene emulsion hot (140°) against the black scale 

 and considers it the best remedy. 



The kerosene emulsion is the most convenient for use, but it is found that the resin wash is 

 cheaper. One difficult) with the resin wash is that the nozzle frequently becomes clogged, bat Mr. 

 Coquillett found that this could be almost entirely prevented by first straining the solution through a 

 piece of thin tarlatan cloth. 



* It is to be observed that the condition of the scalo-insectB, whether old or young, &c, has to be also considered ; 

 this is a matter rather to be dealt with under the head of the several species. Sometimes the empty sacs make a con- 

 siderable show after the insects havo left them, but of course there would be no use in spraying these ! 



