Bulletin 151, Truck and Garden Insects


plant so that a severely-infested plant is well-webbed. They
use this web as a road over which to travel, but it also serves
to hold the eggs to the leaves and perhaps tends to lessen the
danger of the mites being washed off by heavy rains. They
spread by crawling from place to place, altho they may be
carried by the wind.
 They damage the plant by sucking the sap from the leaves.
Each puncture is extremely minute but in the case of a severe
infestation the plant becomes white, the chlorophyll or green
coloring matter being removed with the sap.
 Control.-As these mites are dry weather creatures, one of
the most effective means of control is frequent and heavy
sprinkling, especially if strong pressure can be had. A field
supplied with the common system of overhead irrigation also
supplies a fairly satisfactory means of control. A stream of
water not only knocks off many of the mites, but the moisture
aids their numerous enemies.
 If sprinkling systems are not available recourse must be
had to insecticides. The best are those containing sulphur in
some form. Free sulphur or some of its compounds may be
used, applying it either dry, or in the form of a spray. Free
sulphur is one of the best remedies for red spiders or mites. It
is somewhat slower in its action than some compounds of sul-
phur, taking often 2 or 3 days or more to do its work, but it
remains active for a long time, frequently 2 or 3 weeks, and
usually kills the mites. Sulphur can be applied dry, and driven
into the vines by hand, or shaken into the vines thru a closely
woven cloth or a perforated can.
 It is better to mix 3 parts of dry sulphur with 1 pound of
hydrated lime. The lime can be bought or made by adding 32
pounds (4 gallons) of water to each 100 pounds of quicklime.
Mix hydrated lime and sulphur thoroly. The best results will
be obtained by applying the dust at night or in the early morn-
ing when the air is quiet and the plants are wet with dew, as
the dust sticks better then. It works better when the nights
are moist and the days bright and sunny, for under these con-
ditions the oxidation of the sulphur takes place more rapidly.
As a spray from 1 to 5 pounds of sulphur to 50 gallons of
water can be used.
 Whether the grower can use the dust or the spray most
economically will depend on a number of things, such as the
outfit that he can obtain, the distance the water must be hauled,