Which term describes pesticides that act by direct contact with pests?

• A. Systemic
• B. Narrow-spectrum
• C. Broad-spectrum
• D. Contact

Answer: (D)

Pesticides that act by direct contact with pests are called contact pesticides. The essential idea is that the chemical must physically touch the pest to have an effect—sprayed on surfaces or applied directly to the pest, and it works without needing the pest to ingest or come into contact with treated plant tissues. This differs from systemic pesticides, which are absorbed by the plant and move through its tissues, so pests must feed on the plant or touch treated parts to be affected. Broad-spectrum and narrow-spectrum describe how many pests a product can affect, not how it works on contact, so they don’t define the mechanism the way “contact” does.