December, ’23] 
armitage: present status of aphycus 
511 
is very troublesome even when cold storage is used, and in many in- 
stances it has been necessary to persist for several years before a success¬ 
ful shipment is made. The successful shipment of material to this coun¬ 
try is only part of the battle. Careful life-history studies of the parasite 
must be made to determine beyond any doubt that it is a primary in its 
habits, that is, that it will not attack any of our beneficial species, as the 
Quaylea does the Aphycus at the present time. With only a very limited 
supply of breeding stock available and with a parasite of more or less 
unknown habits, this is difficult and frequently results in the loss of the 
colony. Often the two sexes do not appear at the same time, with the 
result that the shipment is finally lost through lack of fertilization of 
the eggs. Most of these difficulties can however be overcome by sus¬ 
tained effort and are not a permanent barrier to success. 
The writer confessses to a feeling of optimism for the future of bio¬ 
logical control work. The field has scarcely been scratched. There 
are thousands of species of beneficial insects throughout the world. 
There are great improvements to be made in the propagation and 
manipulation of species already available. The work has its limitations 
just as does the control of human disease by the use of serums, vaccines 
and antitoxins, but even partial success will return a large profit on the 
sum invested in such projects. 
THE PRESENT STATUS OF APHYCUS LOUNSBURYI HOW. IN 
SOUTHERN CALIFORNIA 
By H. M. Armitage, University of California , Citrus Experiment Station 
Abstract 
In the “uneven hatch” areas secondary parasitism has precluded Aphycus 
lounshuryi How. becoming, by itself, an adequate means of control of black scale, 
except, possibly, at irregular intervals. Eight hyperparasites are known to attack 
Aphycus and three others are under suspicion. It is, however, of much value in the 
uneven-hatch areas as an aid to fumigation by evening up the hatch. 
In the interior or “even-hatch” areas, low temperatures which cause retarded 
development of Aphycus, particularly in the pupal stage, during the one short 
period when it might alone control the scale, prevents its doing so. Aphycus, with 
Scutelhsta cyanea and Rhizobius ventralis, completes a sequence of enemies attacking 
the black scale and this fact offers a possibility of control. 
The distribution of Aphycus lounshuryi has been so complete, both with and 
without human agency that it is safe to say there is hardly a citrus orchard, or for 
that matter a planting of ornamentals or growth of native shrubbery in Southern 
California, infested with black scale, in which it is not possible to find Aphycus or 
evidence of its work. In spite of the many factors operating to its disadvantage it is 
without question a most valuable addition to the parasite fauna of California. 
Four years observation on the work of Aphycus lounshuryi How. as a 
parasite of the black scale, following its introduction and successful 
establishment in the citrus orchards of Southern California by the 
