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July 23, 2019

F. William Ravlin: Insects: Friend or Foe?

F. William Ravlin is a professor and chair of the Department of Entomology in the College of Agriculture and Natural Resources.

As a biologist, I appreciate how the slowdown of summer on campus gives us the opportunity to notice the natural, quieter world around us. Every summer for several years, I’ve been treated to watching great golden digger wasps (Sphex ichneumoneus) making their living across the street from the Natural Science Building.


Digger wasps are terrific animals with brilliant color, highly programmed behavior and, in my opinion, “pleasant personalities.” You’d never know they’re there until you see them busily excavating and provisioning nests with katydids.

One of the most interesting aspects of digger wasps is their repetitive behavior; moving in and out of a nest, carrying small rocks, soil and other bits only to fly away and return with a paralyzed katydid to lay in a very precise way in front of their nesting hole.

The katydid is always positioned at the “proper angle” so that after a quick check of the nest, the wasp can drag the katydid by the antennae into the hole, making an excellent meal for a developing digger wasp larva.

These wasps are harmless, not aggressive, and seem only to be marginally interested in my presence. However, someone obviously felt threatened by the wasps and made an insecticide application around six to 10 nests. Needless to say, I was and am disappointed and dismayed.

The reason for telling this tale is to encourage people to take every opportunity to help others understand the importance of insects, to encourage them to identify the good guys from the “less good guys,” and to enlist them in sharing how insects impact major issues of the day.

Here is a short list of resources about global challenges requiring a better understanding of insects:
• Recent studies showing the decline in multiple insect species and why that matters. (Toward a world that values insects, Science)
• Increases in vector-borne diseases. (Challenge: Public health, as related to vector-borne diseases, A Grand Challenge Agenda for Entomology)
• Challenges to developing and sustaining a global food supply. (Challenge: Feed the World, A Grand Challenge Agenda for Entomology)
• Threats posed by invasive species. (Challenge: Invasive species – global trade, biodiversity and climate change, A Grand Challenge Agenda for Entomology)
• The need to conserve and where possible, manage ecosystem services such as pollinators. (MSU Extension pollinators and pollination)

The MSU digger wasps suffered a setback, but I expect them to be back next year same time, same place. Will we make a safe space for them?