Tuesday’s Tips — Spinosad for Garden Pests

Of all the organic products we can use to eliminate pests in the garden Spinosad (spin-OH-sid) has perhaps the most curious back story.

A scientist who was part of a team that was searching for new naturally occurring pest controls was on vacation in the Caribbean in 1982. He was poking around an old abandoned rum distillery and decided to take a few soil samples home with him. Back at the lab they fermented the samples and three years later found that the products of the fermentation had insecticidal activity. To make matters even stranger, this new species of soil dwelling bacterium called Saccharopolyspora spinosa, a rare actinomycete, has never been found anywhere else in the world. It is one of those things you read and think, “What are the chances?”

Spinosad is safe for use on ornamentals, vegetables and fruit. It must be consumed by the insect to be effective. It can be used to control a variety of pests including:

  • Cabbage worms
  • Caterpillars
  • Coddling moth
  • Corn borers
  • Fruit flies
  • Leaf beetle larvae
  • Leafminers
  • Rose slugs (sawfly larvae)
  • Sawflies
  • Spider mites
  • Thrips
  • Tomato hornworms

A note of caution here: Spinosad is highly toxic to caterpillars. That means that it will kill good caterpillars as well as bad. If you have a butterfly garden or plants that attract butterflies, DO NOT spray Spinosad when these caterpillars are feeding. You will kill them.

Spinosad is mildly toxic to fish so be careful spraying it around ponds. It can be toxic to bees and other non-leaf feeding insects if they come into contact with it before it has dried on the leaf. That means that you should spray the product only in the recommended amounts (READ PACKAGE DIRECTIONS!), at the recommended intervals, and at dusk when bees and other beneficials are less active. This gives it time to dry on the leaves where it will still be ingested by pests, but where it will not affect the beneficials.

Spinosad has a very low toxicity for mammals and non-leaf feeding insects including sucking insects like aphids, scale, or mealy bugs. Here’s a link to more information from Cornell University’s Resource Guide for Organic Insect and Disease Management.

Remember, just because a product is labeled “organic” doesn’t mean that is without risk. This is a product that can kill living creatures, albeit pests; use it only if you must and with care. The goal is always to keep the garden in balance so pull this trigger only when things are beginning to get out of control, not when you see a few ragged leaves. We need some of the bad bugs around so that the good bugs that eat them will stay in our gardens.

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