PRESS BULLETIN 155
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
S PLANT-BUGS IN ORANGE GROVES
By P. H. Rolfs
The amount of injury done by a single bug in an orange grove would not
be perceptible, but when they collect in hundreds on a single tree the damage
is very material. It is still worse if they congregate by thousands, as has oc-
curred and been substantiated by actual count. In some instances the amount
of damage done to single trees has been as high as 75 per cent. of ,the crop,
and correspondents have informed us of certain trees on which every fruit
had been ruined by bugs. In some groves the damage done by them in a
-single year has amounted to hundreds of boxes of fruit.
The key to the remedy is to starve the bugs while young and small.
(It does not always follow that if grass and weeds are allowed to grow in
the grove that there will be an attack of plant-bugs. This is rather the ex-
ception than the rule.)
1. Mow the grass and weeds that occur in the grove, as soon after the
rainy season as possible.
2. Begin by mowing next to the tree. Leave until later the central
strips, which are most easily mown. Then clean up thoroughly around the'
trees. This will cause the young plant-bugs to be drawn away from the
trees to the central strips, rather than towards the trees as is usually the
case. Frequently in mowing the groves, especially if the grass is wanted
for hay, the middles are mown first, and then the part between the trees is
cut, leaving four, more or less triangular-shaped, patches of grass and weeds
around each tree. The young plant-bugs travel to these small green patches
near the trees. After these dry up, there remains but a short distance for
them to go to the fruit. Thus, while they would fedd by preference on grass
and weeds, they are forced to feed upon the fruit or starve.
3. Destroy all weeds around the edges of the grove. Usually the most
serious injury occurs .to the outside rows.
4. In case the bugs have become numerous and are injuring the fruit,
September 24, 1910
much relief can be effected by trapping methods. The most successful plan,
and the one that is most frequently employed, is to place handfuls of broken
cottonseed or cottonseed meal under the trees. Various species of plant-bugs
are fond of this material, and will congregate on it in preference to attacking
the fruit on the trees. Then, in the morning, before the plant-bugs have
become active, they may be sprayed with some strong contact insecticide.
Pure kerosene is one of the most efficient sprays, though of course it cannot
be used on trees without danger of doing injury.
5. In the early mornings, especially during cool weather, the bugs are
sluggish and inactive. At such times they may be shaken from the trees
on to a large sheet, and then destroyed.
6. Sometimes the plant-bugs congregate on certain trees by hundreds and
even thousands. Tests made by Experiment Station workers show that strong
kerosene emulsion, strong whale-oil soap solution, and resin wash, prove more
or less effective. They cannot be relied upon, however, for killing every bug
Kinds of Bugs
The Cotton Stainer or Red Bug (Dysdercus suturellus) occurs in all
sections of the State of Florida, and is likely to be one of the severest pests.
It is especially drawn to tangerines. The round oranges and grapefruit do
not, however, escape its attacks. The Green Soldier Bug (Nezara hilaris)
occurs also in nearly all parts of the State. While the young of this bug
probably do little damage, the full-grown or mature bug is likely to prove
a severe pest. The Leaf-footed Bug (Leptoglossus phyllopus) in all stages
of its growth feeds on citrus trees. Its young are likely to congregate on
tender young shoots, and in some cases cause these to die off. The Small
Green Plant-Bug, the Small Gray Plant-Bug, and quite a number of others, are
apt to do more or less damage during the cool spells of early winter.
The breeding places of these bugs are among the grass and weeds oc-
curring in the grove. With the possible exception of the leaf-footed bug, they
prefer the grass and weeds to the citrus trees. Groves that have been planted
to velvet beans, beggarweed, or cowpeas are more likely to suffer from their
attacks than groves that have growing in them crab-grass, crowfoot grass, or
other plants of this family. The Spanish cocklebur (Urena lobata), which
occurs from Central to South Florida, is one of the favorite breeding places
for the cotton stainer.
State papers please copy.