Which management approach is described for silver spotted tiger moth tents?

• A. Remove tents and treat with Bacillus thuringiensis (Bt).
• B. Use broad-spectrum insecticides on the trunk only.
• C. Avoid any treatment; rely on natural predators only.
• D. Apply systemic fungicide to suppress the pest.

Answer: (A)

This question is about managing caterpillar tents with a targeted, biological approach. Removing the tents cuts the immediate habitat and starving or displacing many larvae, while applying Bacillus thuringiensis (Bt) provides a safe, selective means to kill the larvae as they eat the treated plant tissue. Bt is a microbial insecticide specific to Lepidoptera larvae; when caterpillars ingest it, the toxin disrupts their gut after ingestion, causing death. Because Bt acts only on feeding larvae, it’s most effective when tents are present and larvae are actively feeding, and it minimizes harm to non-target organisms and the tree compared with broad-spectrum sprays.

Why not the other options? Spraying broad-spectrum insecticides on the trunk alone often misses the caterpillars inside the tents and disrupts many beneficial species. Waiting for natural predators to control the outbreak may allow significant defoliation to occur before balance returns. A fungicide has no effect on insects, so it won’t help control the moth tents.