1. small insects with delicate wings that live for only a short time as adults, typically emerging in large numbers near water in late spring or early summer

Examples

• Thousands of mayflies swarmed around the lake at dusk.
• The mayflies only live for a day or two after they emerge from the water.
• Fishermen know that trout feed heavily when mayflies are hatching.
• The car windshield was covered with mayflies after driving near the river.
• Mayflies spend most of their lives as aquatic nymphs before their brief adult stage.
• The annual mayfly emergence creates clouds of insects around the waterfront.