Agriculture Reference
In-Depth Information
Plain old soap (not detergent, but soap) kills a number of
insects by dissolving a waxy coating that they need to breathe
and preserve moisture. Specialized insecticidal soaps can be
used, or else a pure castile soap (such as Dr. Bronner's),
mixed two tablespoons per gallon of water. Insecticidal soap
will effectively control aphids, white flies, scale, spider mites,
and thrips. It needs to be reapplied fairly frequently—about
weekly—to interrupt the life cycle of the target pest.
Light horticultural oils are highly refined mineral oils that
control the same insects as insecticidal soap by covering and
smothering the pest and its eggs. Mix and apply according to
label directions.
Table 14: Common Microbial Insecticides
Microbe
Pests Controlled
Notes
Bacillus
thuringiensis
var. kurstaki
The caterpillar
stage of a wide
variety of moths
Will not control codling
moths
Bacillus
thuringiensis
var. israelensis
Mosquito, black
fly, fungus gnat
Bacillus
thuringiensis
var. san diego
Colorado potato
beetle
Because of grasshopper
mobility, may not work
for small yards
Nosema
locustae
Grasshoppers
Both oils and soaps should be tested on a single plant first,
then wait a day, because they can be toxic to certain plants.
(Their degree of toxicity to plants varies with heat, sunshine,
