Which product is classified as a biological pesticide used to control caterpillars in turf?

• A. Spinosad
• B. Bacillus thuringiensis (BT)
• C. Imidacloprid
• D. Pyrethrin

Answer: (B)

Bacillus thuringiensis (BT) is a microbial pesticide specifically used to target caterpillars in turf. It works because the Bacillus thuringiensis bacteria produce Cry proteins that become toxic when caterpillars of Lepidoptera eat treated turf. Once ingested, these toxins disrupt the insect’s gut lining, leading to death. This mode of action makes BT a selective, biological option ideal for suppressing armyworms, cutworms, and other caterpillars without broad-spectrum impact on mammals or many beneficial species when used as labeled. Because BT is a living product that degrades in light, applications are often timed and re-applied as needed after rain or sun exposure for continued control. Spinosad is also a biological insecticide but is not the classic, caterpillar-specific turf option; imidacloprid is a systemic chemical, and pyrethrin is a botanical insecticide, so they don’t fit the description of a biological caterpillar-targeting product as neatly.