Approximately what percentage of the described insect species are pests?

• A. About 5 percent
• B. Less than 0.5 percent
• C. About 25 percent
• D. Over 50 percent

Answer: (B)

The main idea here is that pest insects are a very small fraction of the total insect diversity. Insects number in the millions worldwide, and only a tiny subset actually causes economic damage to crops, stored products, or human health. That’s why the estimate is that only a minuscule portion—less than half a percent—becomes pests. It’s easy to assume many insects are pests because problems with crops or stored goods get a lot of attention, but ecologically and taxonomically, pests are rare relative to the whole group.

So this option best fits the reality: the vast majority of described insect species do not behave as pests. The other percentages would imply a large share of insects are problematic, which contradicts the widespread presence of non-pest, beneficial, or neutral species in ecosystems.