I T 6 
FLORIDA STATE HORTICULTURAL SOCIETY 
yellowish dust. It would take approxi¬ 
mately 200 mites placed end to end to 
cover an inch. The adult is lemon col¬ 
ored, triangular in shape and three times 
as long as broad. It possesses four legs 
on the front end of the body and two 
bristled hairs near the caudal extremity. 
It can crawl quite rapidly from place to 
place. It has also been observed to bring 
its rear end toward the front end in a little 
heap and then straighten out suddenly. 
The result would change the location of 
the mite sometimes as much as an inch. 
No doubt this is one way it goes from one 
leaf to another. The adult mite deposits 
eggs which are spherical and transparent. 
At the expiration of about five days these 
eggs hatch. The little mite is also yellow 
in color, but of a lighter shade than the 
* adult mite. Within a week or ten days 
it undergoes a molt, when it is full grown. 
The life history of a rust mite, therefore, 
may be considered about two weeks, that 
is, it takes two weeks for the species to 
go through its life cycle. It is interesting 
to know that even in winter Hubbard has 
found as many as 75,000 mites on a sin¬ 
gle leaf, and there is no doubt that in 
- 
summer time this number is much greater. 
FOOD PLANTS 
Citrus fruits and trees are given in the 
literature as the only food plants. I have 
found a mite on roses which resembles the 
rust mite of the orange, but further 
examination will be necessary before any 
positive statement can be made in regard 
to the matter. 
DAMAGE 
This pest may be found on the leaves 
of citrus trees throughout the entire year. 
It is more frequently found on the upper 
surfaces of the leaves than on the under 
surfaces. In fact perhaps 99 per cent of 
the mites and eggs will be found on the 
upper surfaces of the leaves. The attacks 
of this pest on the leaves are not followed 
by rust. The surfaces of the leaves be¬ 
come finely corrugated and lose their 
gloss. While it is certain they suck the 
juices from the leaves there is no definite 
knowledge of how much damage they do 
by this habit. It stands to reason, how¬ 
ever, that an orange leaf which is covered 
with rust mites must lose much of its 
juices and therefore cannot perform its 
functions as well as one which is free. 
This aspect of the pest is not usually giv¬ 
en sufficient consideration. 
It is generally believed among the 
orange growers that a rust orange con¬ 
tains a larger percentage of sugar than a 
bright orange. In several instances I 
found by tasting russet and bright fruit 
from the same trees that this was not the 
case. There are no analyses which will 
•either substantiate or contradict this be¬ 
lief, but I am of the opinion that it is 
a Florida myth. 
The chief damage which this pest-causes 
results from the russeting of the fruit. 
This russeting is a discoloration due to 
the effect of the juices which ooze out 
from the punctures made by these mites in 
the rind. The action of these juices pro¬ 
hibits the growth and expansion of the 
rind and thus prevents the fruit from 
getting to be as large as it would have 
