Thanks for your question.

Populations of most organisms are cyclic. This is true for fireflies. Depending upon environmental conditions and their own internal biological clocks, there will be years in which their population numbers will be high and there will be years in which their numbers are low. There is not much we can do about it. There are anecdotal articles existing claiming that our warming Minnesota climate is reducing the numbers of fireflies. Yours is the first report that we’ve received about 2024 numbers being low in your area. Having now been alerted to this possibility, we will monitor the situation in case something is going on beyond just Aitkin County. Here is some additional information for you to look at:

https://www.startribune.com/whats-the-latest-lightshow-in-town-fireflies-at-the-minnesota-arboretum/600379459/

https://www.firefly.org/

https://worldpopulationreview.com/state-rankings/fireflies-by-state

Thank you for your concern about these very remarkable animals. I don’t think that your spot spraying had any influence.