Which of the following is not a pest of crops?

Analyze the question: We need the organism that is NOT a pest of crops. A crop pest is any organism that feeds on or damages crops, either in the field or in storage.

Explain the concept: Pests are classified by what they attack:

• Crop pests damage plants or stored produce.
• Household or human or animal pests mainly feed on blood or live in homes.

Go through the options:

• A. Bird: Birds such as weaverbirds (quelea) eat grains like rice, millet and sorghum, so they are crop pests.
• B. Rodent: Rats and mice eat crops in the field and in storage, so they are crop pests.
• C. Bed bug: Bed bugs (Cimex lectularius) are blood-sucking ectoparasites. They live in beds and furniture and feed on human blood. They do not feed on crops, so they are not crop pests.
• D. Grasshopper: Grasshoppers chew leaves and stems and can destroy farms, so they are crop pests.

Answer: The bed bug is the only one that does not attack crops.

Tip: Link each pest to its food source. Bed bugs, lice, fleas and mosquitoes feed on blood, so they are pests of humans or animals. Locusts, grasshoppers, weevils, rodents and quelea birds feed on plants or grains, so they are crop pests. In "which is not" questions, look for the one that doesn't fit the group.