I washed my truck this morning and it took some extra effort to get all the multicolored bug splats off the front end. I’m afraid many of them were from butterflies. There has been a big flight of painted ladies and red admiral butterflies in the past couple of weeks. They have been feeding heavily on flowers planted along many of our highways. They tend to fly low, at about grill/windshield height. Even though they’re fast fliers for butterflies, they’re still slow; too slow to get out of the way. Vehicles smash them by the hundreds when they venture even a few feet into the traveled portion of a busy road. Many are fatally injured even by near misses when the turbulence generated by passing vehicles slams them into the pavement. These butterflies are common enough that decent populations of them are likely to survive the slaughter.
I mentioned last week how happy I was to finally be seeing a few monarch butterflies visiting the milkweeds I’m growing just for their benefit. I found a single monarch caterpillar happily munching on a milkweed leaf, too. I’m afraid that my vehicles, alone, have killed more monarchs than are visiting my milkweeds, though. Not all roadsides have milkweeds, but adult monarchs gather nectar from a variety of flowers. They’re attracted to wildflower roadsides even without milkweeds, where they’re vulnerable to vehicle strikes just like all the other insects. Every one of the thousands of vehicles traveling our roads probably has as many butterflies and other insects mashed onto their front ends as mine. I worry that the beautiful flowering roadsides we have created may be a baited death trap for too many butterflies that visit them.
Painted ladies and red admirals are also migratory butterflies, though not as famous for that as monarchs are. Like monarchs, it takes several generations to repopulate northern parts of their range where they can’t survive cold, and then return to warmer southern wintering areas. Their populations spread out and don’t end up at one spot like monarchs do, making them less vulnerable to occasional cold events that can kill thousands of monarchs. Other butterflies complete their whole life cycle right here. Those that are feeding and breeding at sites away from well-traveled roads probably won’t end up on somebody’s grill. Migratory butterflies, on the other hand, have to fly hundreds and even thousands of miles. They fuel that migration on nectar from flowers they find along the way. Many, if not most, of those flowers are now growing in road ditches; especially in the heavily agricultural upper Midwest. Fields of clover and old pastures with some flowering thistles (a butterfly favorite) are few and far between these days.
What are the odds of a migrating butterfly not meeting an untimely end, given the hundreds of roads they must cross or feed along? I used to pilot light airplanes and encountered monarchs higher than 1,000 feet above the ground. A few of them ended up smashed on the wings, but those high fliers stood a much better chance of survival than their roadside brothers and sisters.
I love the flowered roadsides that are a treat for the eye and a haven for bug-eating young birds. A few birds get killed by vehicles, too, but birds fly higher and faster. They also see danger coming at a distance and avoid it far better than butterflies can. The butterfly dilemma is a tough one. One answer is more flowers farther away from roads, or at least along roads without heavy traffic. That’s a tough goal to achieve around here where most of the land is row crops rather than pasture or CRP type plantings. Every little bit helps, though. A patch of milkweeds or other nectar producing flowers (even native thistles) here and there in odd corners of fields and along drainage ditches could help improved the odds of survival for some butterflies and keep them off the front of vehicles. I’d put a bumper sticker saying “I brake for butterflies” on my truck, but I’m afraid I couldn’t brake soon enough to save many and would probably cause accidents with other vehicles if I did. So, I’ll sadly have to keep scrubbing butterfly leftovers off my grill and windshield.
Steve Lekwa is a former director of Story County Conservation.