Spinosad
A bacterial-derived insecticide that is highly effective against caterpillars, thrips, and certain beetles while being safer for most beneficial insects than conventional alternatives.
What it is
Spinosad is produced by the fermentation of Saccharopolyspora spinosa, a naturally occurring soil bacterium first discovered in an abandoned rum distillery in 1982. It is approved for certified organic production. Commercial formulations contain the active compounds spinosyn A and spinosyn D.
What it does
Spinosad activates nicotinic acetylcholine receptors in insects by a unique mechanism, causing uncontrolled neural activity, paralysis, and death. It is effective through both ingestion and direct contact. It has significantly lower toxicity to most beneficial insects than pyrethrins, though it can harm bees when wet.
When to use
Apply when caterpillar or thrips pressure is confirmed and threshold populations are reached. Most effective against young, actively feeding larvae. Apply in the morning or evening when pollinators are less active, or target spray to avoid flowering areas. Ingestion activity makes it effective even with incomplete coverage.
When not to use
Avoid spraying directly onto open flowers or bee-visited plants while wet, as spinosad is harmful to bees on direct contact. Do not apply more than four times per season on the same crop to avoid resistance development. Rotate with different insecticide classes where resistance is a concern.
How to apply
- 1
Shake the spinosad concentrate well and dilute to the label-specified rate, typically 1/4 teaspoon per quart of water.
- 2
Add a small amount of castile soap (a few drops per quart) to improve leaf adhesion and coverage.
- 3
Apply in early morning or evening, covering all leaf surfaces where caterpillars or thrips are feeding.
- 4
Focus coverage on the undersides of leaves and any tightly wrapped foliage where pests hide.
- 5
Repeat applications every 7 - 10 days as needed, rotating to a different class of insecticide after four uses to prevent resistance.
Garden, by Willowbottom recommends only organic, wildlife-friendly solutions. No synthetic pesticides, no harmful chemicals - ever.