Specialist Predators

by Carl Strang

Yesterday I mentioned one hazard that limits the number of katydids that achieve reproductive maturity. Gwynne referred to another danger, this one a group of wasps that specialize on katydids as food for their young. This caught my attention, as two members of genus Sphex have been abundant at Mayslake Forest Preserve in recent years.

The great black wasp is especially common. I have seen as many as 8 at a time visiting swamp milkweed flowers in the south stream corridor prairie.

The great black wasp is especially common. I have seen as many as 8 at a time visiting swamp milkweed flowers in the south stream corridor prairie.

Less abundant, but a consistent presence, great golden diggers likewise catch katydids to feed their young.

Less abundant, but a consistent presence, great golden diggers likewise catch katydids to feed their young.

Each female wasp needs more than one katydid for each egg she lays in her burrow. That can add up to a significant impact on a katydid community. Being aware of such ecological factors enriches our understanding of the local abundance and distribution of singing insects.

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