When Mayflies Rise Together

Transcript

Mayflies are insects whose young live and grow in water before emerging as adults. In Odd Showers, Sir George Duncan Gibb describes mayflies, which he calls ephemerae, appearing in immense numbers along rivers and streams by the St. Lawrence, perhaps across hundreds of miles. The striking detail is his account that they could hatch simultaneously in millions. Gibb explains the mass appearance by saying that many emerge from their pupae at the same time, after their aquatic stage. He also records dense gatherings of caddis-flies, mosquitoes and gnats, locusts, and ants. These are other reports of swarming insects, not proof that every swarm forms for the same reason. The lesson is to distinguish what an account describes from the explanation offered: a huge gathering may seem like a shower, while its cause depends on the particular case.