Bonide Captain Jack's Bacillus Thuringiensis (BT) Spray Review

Our Verdict

BT is a bacterium that has to be eaten to work, and it only affects the larvae of moths and butterflies. On a lawn that means sod webworms and armyworms, both of which are caterpillars, and it means genuinely sparing bees, beetles, earthworms and everything else in the turf — a level of selectivity no broad-spectrum insecticide can offer. That same specificity is the catch. White grubs are beetle larvae, not caterpillars, so BT does nothing to them no matter how much you apply; the same goes for chinch bugs, billbugs and fire ants. Buy it because you have identified caterpillars, not because it is the organic option on the shelf. Timing matters too: it degrades in sunlight and works best on small larvae, so late afternoon on a young infestation.