112 
FLORIDA STATE HORTICULTURAL SOCIETY 
unit of surface as leaves free of sooty 
mold. 
The explanation of this increase is as 
follows: The young crawlers react pho¬ 
totactic to the average degree of illumina¬ 
tion met with in a citrus tree; i. e., they 
avoid such light. This leads them to 
crawl into any shaded corner as between 
two fruit trees that are in contact, under 
the calices of fruit where they are always 
relatively abundant, or under loose-fitting 
sooty mold, and especially under colonies 
of the woolly whitefly. This leads to the 
concentration of crawlers in such situa¬ 
tions. Here they are partially protected 
from their enemies, such as chrysopa lar¬ 
vae, lace-winged flies, the lady-beetles, 
etc., and perhaps also from their fungous 
enemies, the spores of the red-headed, the 
gray-headed and the black scale-fungi. 
So marked is this tendency of the scales 
to congregate under an old colony of 
howardi, that it is possible to tell just 
where on the lower surface of a leaf, 
there is a colony of howardi by noting the 
yellow areas on the upper surface. The 
writer has in several instances counted 
over a thousand purple scales per square 
inch in these old colonies, not including 
crawlers. Five hundred adult scales, i. e., 
those that have reached the egg-laying 
stage, have frequently been counted per 
square inch. These old colonies of how¬ 
ardi, if sufficiently numerous, become the 
centers from which the trees become heav¬ 
ily infested with scale. 
Habits. The adults are markedly 
more sluggish than those of A. citri. A 
jar of the limb that would cause citri to 
take to wing has little effect on howardi. 
So sluggish are they indeed that the adults 
frequently lay their eggs on the same 
leaf on which they grew and emerged. 
There is not the marked tendency to seek 
out the new and tender growth that is so 
characteristic in A. citri and especially in 
A. nubifera. They seem indeed to prefer 
leaves that have recently completed their 
growth and turned a dark green to either 
the very young or the very old leaves. 
This sluggishness greatly retards their 
spread through a grove. In one of the 
severest infestations that have come under 
the writer's notice, they were confined to 
one-half of a ten-acre grove. None what¬ 
ever were seen at the other side. 
On the other hand, this sluggishness is 
a distinct aid to their transportation to a 
distance on the clothes of travelers and 
vehicles. The writer saw adults clinging 
to the clothes of the owner of one of the 
above-mentioned groves after he had 
driven in a buggy three miles. In Arca¬ 
dia, in December, 1912, the writer found 
howardi only in some trees in front of 
the hotel and in a small door-yard grove 
across the street, plainly suggesting that 
the insect had been brought to town on 
the clothes or luggage of travelers. A 
year later the insect was found by Dr. E. * 
W. Berger to be generally distributed in 
the groves about town and as far out as 
five miles. 
The crawlers of this species are also 
very sluggish and settle down very near to 
the place where the eggs were deposited. 
This results in most of the larvae and 
pupae being collected in colonies instead 
of being scattered more or less uniformly 
over the surface of the leaf, as with the 
other species. These groups or colonies 
average a score or more of individuals 
and are a striking feature of howardi. 
The eggs of this species are laid in cir- 
