December, ’23] 
FULLAWAY: BIOLOGICAL CONTROL IN HAWAII 
533 
number of consignments made, and the results have varied to a very 
high degree, from the perfectly satisfactory control of Ancmala orientalis, 
achieved through the introduction and establishment of a single enemy, 
Scolia manilae, to the fruitless search for wire worm enemies, which has 
extended over four years. An entirely satisfactory control of the sugar 
cane leaf hopper has only been achieved after twenty years’ work, in¬ 
volving the introduction of more than a score of enemies. The control 
of the Mediterranean fruit fly has not been entirely satisfactory owing to 
the fact that the larvae occur in many fruits with a thick pulp, where the 
parasites which are effective to a high degree in thin-pulped fruits, 
cannot reach them. Recent introductions to improve the control of 
the avocado mealy bug, Pseudococcus nipae, have given marvellous re¬ 
sults in a very short time, but in the case of other coccid species the 
control exerted by parasites and predators has been less marked. 
A perplexing question in our experience with this work has been, 
Should all the obtainable enemies of an injurious species be introduced 
or should a complex be avoided and dependence put upon one effective 
enemy. I believe this, in the light of our experience, is still a debatable 
question. 
I realize that in this hasty survey of the subject I have only skimmed 
its surface, but I have been warned of a time limit. In conclusion I 
would add that if the application of this method to the subjugation of an 
insect pest does not always result in a full and complete control of the 
pest, it at least often brings its multiplication within such bounds that 
artificial methods can be used with some degree of satisfaction. Also, 
that the main defect of the method from a practical standpoint appears 
to be its limited application. 
Afternoon Session , September ig, ig 2 j 
R. E. Campbell, Chairman 
JOINT MEETING WITH ECOLOGISTS, PLANT PATHOLOGISTS 
AND PLANT PHYSIOLOGISTS 
Subject: Ecological Factors Influencing Distribution and Severity of 
Insect Pests and Plant Diseases. 
Papers were presented by H. S. Fawcett and E. T. Bartholomew, and 
afterwards discussed by the members present. 
A telegram was sent to the members whose homes were burned in the 
Berkeley fire and included W. B. Herms, H. H. P. Severin and Dr. E. C. 
Van Dyke, all of the Entomology Division, University of California. 
