450 QUEENSLAND AGRICULTURAL JOURNAL. [1 Juxx, 1899. 
A perusal, however, of the article on the subject will throw much light 
upon the value of the process. Mr. Benson bas thrown himself heart and soul 
into the business of destroying the scale insects on citrus fruits, in addition to 
carrying out his other onerous duties as instructor in fruit culture ; and in this 
joint attack on the pests by Mr. Tryon and himself, we are sure that he will be 
found to have thrown so much light on the subject as to materially lessen the 
troubles of fruit-growers, who need only avail themselves of the assistance 
readily extended by the Department of Agriculture through the medium of the 
experts to eventually overcome, or at least minimise, the evil effects of insect: 
fruit pests of all kinds. 
EXPERIMENTS IN CYANIDING ORANGES. 
By ALBERT H. BENSON anp HENRY TRYON. 
Aur citrus fruits infested by scale insects that are exported from Queensland 
to the southern colonies having to be treated by hydrocyanic acid gas prior to 
shipment, we have carried out the following experiments in order to definitely 
determine— 
First.—The strength of hydrocyanic acid gas that is required to destroy 
scale insects on citrus fruits. 
Second.—The effect of hydrocyanie acid gas on the fruit when used at 
different strengths and under different conditions. 
The experiments have been conducted by us in an airtight cyaniding 
chamber at the offices of the Department of Agriculture, said chamber haying 
a capacity of 140 cubic feet. 
In all of the experiments the fruit was exposed to the action of the gas 
for one hour, and the chamber being wholly unoccupied, save for the presence 
of the nine oranges used in each group of experiments, both the fruit and the. 
insects attached to it were in each case subjected to this unimpaired. 
The oranges experimented upon averaged about 8 inches in diameter, - 
and had a fairly rough skin varying from one-fifth to one-sixth of an inch in 
thickness, and were grown by Mr. S. Voller at Enoggera, near Brisbane, on 
trees in full bearing. The soil of Mr. Voller’s orchard is a porous, 
disintegrated granite that has been heavily manured with butchers’ offal, and 
the trees were in vigorous health, though slightly suffering from the dry 
weather. The skins of the fruit were moderately dry and tough, the fruit 
being gathered on the day previous to that.on which the experiments’ were. 
carried out. 
They were badly infested with Aspidiotus ficus (Circular Black Scale), 
Chionaspis citri (White Scale), and Mytilaspis Gloveri (Glover Scale). 
In each group of experiments one-third of the fruit was left untouched, 
one-third of the fruit was dry-scrubbed with an ordinary scrubbing-brush to 
remove the scales, and the remaining third was sprinkled with water, but had no 
scales removed. Dry scrubbing of scale-infested fruit prior to marketing is. 
often resorted to by our growers, and we were anxious to see the amount of 
injury in fumigating fruit traceable thereto. By the application of water a 
wet condition of the fruit was produced similar to that often exhibited by such 
as has been packed immediately after being gathered. 
