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JOHN A. STARNES JR.Bacillus thuringiensis lets gardeners target these pests in veggie plots and lawns while observing a truce with insects among the ornamentals.
Spring is caterpillar time in Central Florida, but before you declare war on them with insecticides (even natural ones), remember that those munching monsters mature into moths and butterflies, many of them cherished for their beauty and grace in our gardens.
Control them only where they do the most harm: in veggie gardens and on St. Augustine lawns that can be ravished by sod webworms.
Organic gardeners get a lot of help from natural allies such as birds and wasps, which eat caterpillars and carry them off to their nests for their young to eat. But we don't want our food crops and lawns ruined, so we need a specific tool to control caterpillars quickly. Fortunately, this silver bullet, around since the 1930s, is available in many garden shops and feed stores: It's a natural bacteria known as Bacillus thuringiensis, or Bt, and is sold under the product names Dipel, Biotrol and Thuricide. Bt is not genetically engineered and doesn't hurt honeybees, earthworms, kids, pets, birds - just caterpillars that ingest the bacteria by biting a leaf sprinkled with it. Once caterpillars get a taste, the organisms multiply inside their bodies, paralyzing their digestive track with crystals of a protein that is toxic to them. As a result, they quit feeding on plants, and within 20 minutes of that first bite, they die.
Use Bt judiciously and only where needed. One application inoculates the organically maintained lawn or veggie garden permanently because the bacteria are soil-dwelling and welcome the absence of fungicides and agricultural antibiotics. Sprinkle the powder on damp leaves or grass; the moisture will bring the bacteria to life. Some folks prefer to mix the powder into bottled water (the chlorine in tap water can kill the bacteria) in their garden sprayer, then spray it only where it is needed.
Though none of us wants our yards pillaged by caterpillars, they are essential to the color and charm of Florida. As more of us invite them in with butterfly gardens, perhaps fewer will become extinct because of habitat loss.
- John A. Starnes Jr., born in Key West, is an avid organic gardener and rosarian who studies, collects, cultivates and hybridizes roses for Florida's climate. He can be reached at johnastarnes@msn.com