518 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
infested with citrophilus mealybug, but insufficient search has been made 
in case of other infestations to justify any conclusion that it will not 
attack the other species. It is believed that this ladybird will become 
of considerable value in the control of the above mentioned species when it 
has had sufficient time to become thoroughly established. 
Through the courtesy of Dr. L. O. Howard, specimens of this ladybird 
were studied by Mr. E. A. Schwarz of the National Museum, who 
reported as follows: 
“The small Scymus from South Africa is most probably identical 
with Scymnus binaevatus Mulsant (1850), described (apparently from a 
single specimen) from “la Cafrerie.” The type is now in the Stockholm 
Museum. Mulsant’s description agrees very well with Mr. Smith’s 
specimens but it is not known to me at present whether or not other 
African species of Scymnus allied to 5. binaevatus have been described by 
recent authors. It would be safe, therefore, to refer to the species as 
“Scymnus (Sidis) binaevatus Muls. ?”. 
THE HISTORY OF HYDROCYANIC ACID GAS FUMIGATION AS 
AN INDEX TO PROGRESS IN ECONOMIC ENTOMOLOGY 
By R. S. Woglum, Entomologist , California Fruit Growers Exchange, Los Angeles , 
California 
Abstract 
Hydrocyanic acid gas fumigation was discovered in 1886. From 1886-1893 it 
underwent decided improvement as a fumigant for citrus trees; 1893-1900, green¬ 
house, nursery stock, stored products and mill fumigation were introduced; 1907-08, 
orchard fumigation was standardized; 1910-13, sodium cyanide displaced potassium 
cyanide; 1912, portable machine generator invented; 1913-14, vacuum fumigation 
developed; 1916, liquid hydrocyanic acid first used for fumigating; 1923, calcium 
cyanide dust experimented with as fumigant. 
The ascendency of American economic entomology during the last 
half of the 19th century appears attributable primarily to the develop¬ 
ment of methods which offered noteworthy relief to agriculturists suffer¬ 
ing from insect depredations. The maintenance of this supremacy in 
pest control has rested largely on the discovery of new or the improve¬ 
ment of old methods or practices. The history of hydrocyanic acid gas 
fumigation during its thirty-seven years of use is peculiarly illustrative 
of entomological progress. It appears a fitting topic at this meeting 
as its discovery in 1886 by Coquillett was made in Los Angeles, the 
first experiments being conducted in the famous Wolfskill Orchard, now 
displaced by the Southern Pacific Station. Much of the later progress 
in fumigation has also been made in Southern California. 
Coquillett’s discovery was the outgrowth of unsuccessful efforts to 
