More on lightning bugs

Homegrown blog readers are still fascinated with lightning bugs. Someone posted questions on an item about lightning bugs that I wrote last year. Here is what she wrote: Does the use of pesticides reduce populations of lightning bugs? Also, are there certain plant species nectar that lightning bugs prefer?

 Donald R. Lewis, of the Department of Entomology at Iowa State University Extension, wrote the following to answer those questions:

Lightningbugs are indeed fascinating.

 (Lightningbug is always written by an entomologist as ONE word, though spell check and many websites disagree.  Similarly, if you use their other common name, firefly, that should also be written as one word.  It makes for odd looking words, but there are entomological rules for these things! )

 The question about “pesticides” is always difficult to answer because of wide misconception of what the word means and how broad that topic really is.  It is not clear what the writer is asking, so the answer is a completely-honest and meaningless reply, “It Depends.”

 If by “pesticide” the writer means herbicides, fungicides, rodenticides, termiticides, avicides, molluscicides, bactericides, piscicides, and dozens of other types, the answer is, No.  These pesticides are not toxic to insects.

 If by “pesticide” the writer mean insecticides, then the answer is, Probably not, but maybe.  And then it gets complicated.

 Lightningbugs spend most of their life (10.5 to 11 months of the year) as larvae living under damp mulch, leaf litter and plant debris.  They are in a location that does not receive insecticide under normal use patterns so larvae and not exposed.    I believe population variations from year to year and from place to place are related to weather and moisture and food differences in these specific larval habitats.

 Adult fireflies are present from late May to the end of July.  They are active at night and rest during the day in tall grass, trees, shrubs and crop fields.  Lightningbugs are not likely to be exposed to most farm and/or urban insecticide applications for several reasons such as formulation applied (granules rather than sprays) or timing (majority of soybean aphid applications are made after firefly season has passed).  Spraying a broad-spectrum, foliar insecticide on firefly resting sites at the time the adults are present could negatively impact them.  From that point of view we would follow IPM guidelines and common sense to minimize insecticide sprays to resting sites to the extent possible. 

 Finally, adult lightningbugs generally do not feed.