FLORIDA STATE HORTICULTURAL SOCIETY 
65 
the keys with the close proximity of wa¬ 
ter which greatly regulates the temper¬ 
atures. Many insect pests are sensitive 
to abrupt changes in temperature. Hence 
we may expect to find insect infestations 
severe in certain localities where others 
prove less favorable to insect activity. 
During the dry winter months in Flor¬ 
ida, the Avocado is generally considered 
in a dormant condition. At this time of 
year various enemies are to be found at¬ 
tacking the Avocado which thrive under 
conditions of little rainfall and low hu¬ 
midity. 
THE AVOCADO RED SPIDER. 
One of the enemies which attacks the 
Avocado during the winter is the Avo¬ 
cado Red Spider, Tetranychus yothersi 
McG. In appearance it is not unlike most 
other red spiders which attack citrus 
trees. By examining the foliage carefully 
the red spiders will appear as mere red 
specks moving in every direction over the 
foliage when disturbed. It is very desir¬ 
able for the grower to be provided with a 
suitable hand lens in order to be better 
able to detect and distinguish between the 
various pests he may come in contact with 
as many of the enemies are rather minute. 
Trees heavily infested with red spiders 
appear in a comparatively short length of 
time under favorable conditions as if 
scorched by fire, the leaves turning brown 
and ultimately dropping. The over win¬ 
ter foliage should remain on the trees un¬ 
til there is sufficient new growth pro¬ 
duced in the spring to take its place when 
normal shedding of the foliage will occur. 
Where the winter foliage is lost prema¬ 
turely the result may be an abnormal de¬ 
velopment of the bloom, and a set back to 
the trees in their activity to sustain the 
proper set of fruit. The grower should 
watch his trees carefully and examine 
them frequently especially on the ap¬ 
proach of dry weather in the fall, and 
when the red spiders are detected in num¬ 
bers while the foliage is still green he 
should prepare to spray and not wait until 
the foliage has become browned and 
scorched. 
Control. 
The Avocado red spider may be con¬ 
trolled by spraying with the regular lime 
sulphur solution at the rate of one gallon 
to seventy-five gallons of water. 
THE AVOCADO LEAF THRIPS. 
Another enemy which may at times be 
seen infesting Avocado foliage is the so- 
called greenhouse thrips of the northern 
states, Helio thrips heniorrhoidalis 
Bouche, which attacks the Avocado in the 
open in Florida. This thrips resembles 
most other thrips in appearance, is black 
in color and about a millimeter in length. 
The first indication of injury caused by 
this thrips is the production of pale col¬ 
ored areas to the foliage due to the ex¬ 
traction of the plant juices. These pale 
areas gradually run together as the work 
of the thrips becomes more in evidence 
over the leaf surface. Later the foliage 
assumes a brown color and appears 
scorched. Eventually the foliage drops 
prematurely as in the case of the red 
spider. 
