62 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
suggested the importation of cottony cochineal insects to combat the 
plant pest. The Queensland Traveling Commission, after two years 
study throughout the world, recommended the introduction of the 
natural enemies of the plant from the Americas. 
From Ceylon this Commission sent a cochineal (. Dactylopius indicus 
Green) to Queensland which was found to be restricted, not only to 
. cactus, but even to a single species of Opuntia called the “tree pear.” 
It was liberated in the Suttor River region where the bulk of this species 
(0. monacantho ) occurred. 
The intervention of the war postponed action on the Commission’s 
recommendation, and the cochineal shifted for itself, more or less. At 
the expiration of the war this cochineal was found practically to have rid 
Queensland of the “tree pear” and not to have attacked other plants. 
In 1920 the Commonwealth Prickly Pear Board came into being to 
tackle the problem from the biological angle. 
The Work of the Commonwealth Prickly Pear Board 
Preliminary arrangements completed, Doctor Harvey Johnston, 
Scientific Controller of the Board, returned to Australia to receive 
shipments from South America by Mr. W. B. Alexander and from 
North America by the writer. 
The work done in Argentine showed the presence of several valuable 
organisms. These include two species of moth-borers ( Cactoblastis 
cactorum (Berg) and C. bucyrus Dyar), two species of pyralids attacking 
new growth ( Mimorista sp. and M. pulchellalis Dyar), and two cochineals 
(.Dactylopius sp. and D. indicus Green). Argentine diseases of prime 
importance are Sclerotinia cactacearum Speg., Phytophthora cactorum 
Speg., and Montagnella opuntiarum Speg. None of these organisms 
are established in Australia. 
The North American work has been carried out from Florida to Cali¬ 
fornia and over northern Mexico. The previous work of Dr. W. D. 
Hunter on cactus insects has been an invaluable aid to the project. Both 
the Board and I have been particular}^ fortunate in having Doctor 
Hunter direct the investigations on this continent. 
«* 
The important cactus diseases of North America are cactus anthracnose 
(Gloeosporium lunatum), zone spot, (G. cactorum ), a bacterial soft-rot, 
and cactus scab ( Hendersonia opuntiae). The phytopathological phase 
of the project will not be dealt with further here. 
Twenty-three of the more important true cactus insects were selected 
for introduction to Australia, the plan being to rely for success upon this 
