APPENDICES. 137 



for the year 1887" {Annual Report of the United States Department 

 of Agriculture for the year 1887). The Figures 17, 18, and 19 have 

 been reproduced from the above report. 



REPORT ON THE GAS TREATMENT FOR SCALE-INSECTS. 



By D. W. COQUILLETT, Special Agent. 



Los Angeles, Cal., 20th January, 1888. 



SIR, I have the honour to transmit herewith my report upon the gas 

 treatment for scale-insects (Coccidce). 



Shortly after my reappointment last July as an agent of your division 

 the supervisors of this county withdrew their offered reward of $1,000 

 for a perfect exterminator of the Icerya, and their reason for so doing 

 is thus given by the Los Angeles Herald : 



" On Saturday last the board of supervisors decided to rescind the 

 reward of $1,000 which they had offered for the discovery of a remedy 

 which would exterminate the White Scale Bug and other pests injurious 

 to fruit trees. They came to this decision for the reason that it is 

 believed that Mr. Coquillett, the Government appointee, has, by his gas 

 system, mastered the problem which has so long been a puzzle to all 

 fruit-growers." 



My experiments have been conducted in the orange groves of Mr. J. 

 W. Wolfskill, of this city. Both Mr. Wolfskill and his foreman, 

 Mr. Alexander Craw, have aided me much in my work, as has also 

 Mr. W. G. McMullen, one of the members of the Los Angeles County 

 Horticultural Commission. 



Your own advice and frequent expressions of confidence have done 

 much toward giving to my work whatever of merit it may possess. 

 Very respectfully, 



D. W. COQUILLETT, Special Agent. 



Prof. C. V. RILEY, U. S. Entomologist. 



The Gas Treatment of Scale-Insects. 



The process of destroying insects on plants in hot-houses by fumi- 

 gating with sulphur, tobacco, and various other noxious substances, 

 has long been in vogue, but up to a recent date this mode of warfare 

 against insect pests has not been extended to trees and plants growing 

 in the open air. The earliest record I possess of any attempt of this 

 kind is a copy of the specifications for a patent (No. 64667) granted to 

 Mr. James Hatch, of Lynn, Mass., on the 14th of May, 1867. The 

 following extracts from these specifications will sufficiently explain the 

 method pursued by Mr. Hatch : 



" The invention relates particularly to the manner of effecting the 

 destruction of insects known as Canker-worms, after their lodgment in 

 trees and while consuming the foliage thereof. * * * I cover the 

 entire head of the tree with a thin cloth of close texture, drawing the 

 edges around the trunk, so as to envelop the branches in a sort of sack. 

 Near the tree I have a furnace, over which is placed a pan containing 

 tobacco, pepper, or other substances, the smoke from which will stupefy 



