1. small dark-colored biting flies that are common near streams and rivers

Examples

• The blackflies were so thick near the waterfall that we had to wear head nets.
• Blackflies are most active during the day, unlike mosquitoes.
• The hikers applied insect repellent to protect themselves from blackflies.
• Blackflies can make outdoor activities unpleasant in certain regions.
• The female blackflies need blood meals to produce their eggs.
• Blackflies typically breed in fast-flowing streams and rivers.