Our Windshields Are Cleaner Then Ever and Why That’s Not Good News

When I was a kid you knew it was summer by the warm sun on my skin, sweet tea, and the splats of hundreds of dead bugs on my windshield and bumpers.

I later moved to Florida for grad school in Entomology and I quickly learned about lovebug season. These flies also known as known as honeymoon flies or kissybugs emerge in the thousands (though it felt like millions) in spring and fall. Short of never moving your car, you could not avoid a car splattered in black from the bodies of these insects. Sadly and oddly they fly while attached to their mates, so cars are just getting in the way of their fun times.

If you fish you are probably familiar with swarms of insects. Many flyfishers depend on swarms of flies, mayflies, and caddisflies to know when to go out fishing. In some parts of the world, the midges emerge in such high abundances that people have inhaled too many and suffocated.

But today we are seeing fewer and fewer bugs on our windshields and bumpers. And while that might be good for your paint, it’s bad for the environment. Surveys of insects have shown recent reductions in abundance by as much as 80%, even in nature reserves.

Why is My Windshield Bug Free?

The windshield phenomenon (or windscreen phenomenon) is the observation that fewer dead insects accumulate on the windshields and front bumpers of people's cars since the early 2000s.

We now have more data on this as scientists and citizen scientists have started adding sticky traps to the front of cars to measure how many insects go splat, known as “splatometers.” The Kent Wildlife Trust has partnered with Buglife to start taking stock of insects smashing into our cars. Between 2004 and 2019, they found 50% fewer insects, in 2021 a 72% decline, and in 2024 a 63% decline from 2021. In urban areas, there less than half as many splattered bugs as in the countryside.

This fits with a number of other studies. A 20-year study measured the number of dead insects on car windshields on two stretches of road in Denmark from 1997 until 2017. Adjusted for variables such as time of day, date, temperature, and wind speed, the research found an 80% decrease of the number of insects. Another study looked at 124,606 insects colliding with windshields along a total distance of 55,000 miles in China and Europe. One of the few studies in the United States, in Utah, suggests that tens of millions of bees are likely killed on western United States roads every day.

What Makes For A Buggy Windshield?

Shape and Speed of Your Car

Pollinators such as bees and butterflies flying closer to the ground are more prone to fatalities caused by vehicles.

The type of vehicle and shape of the front of the vehicle affects the percentage of flying insects that get smashed into the front grill or windshield rather than get trapped in airflow over the top of the vehicle. There may be something about this shape as more recent car models are associated with more killed insects. Obviously large semi-trucks with a big grill and windshield will catch large numbers of insects.

Insects are less likely to hit the windshield when a vehicle is traveling slower. This is due to the “physics of airflow” around the vehicle. They either wind up getting trapped in the airflow or flying above the car.

Many insect fatalities occur at night because they are nocturnal and/or are attracted to lights, such as your headlights (or porch lamp, for instance). Insects that are nocturnal use moonlight to direct their flight path.

The Weather

Insect abundance should increase in spring as temperature increases, because this is when many insects emerge and are looking for mates or new homes. This is also because most insects “hibernate,” or overwinter in a dormant pupal stage during the winter.

Higher wind speed and more cloud cover reduces the abundance of insects.

Nearby Parks and Preserves

In one study in Utah scientists found the highest bee mortality estimates are in parts of Utah that are home to busy national parks. The route with up to 16 million bees hit per day occurred along the route from Salt Lake City to Moab, Utah, near Arches National Park. Similarly, the short stretch of road from St. George, Utah to Virgin, Utah near Zion National Park, had an estimated 1.4 million bees hit per day. This is similar to some research in India that found insect road kills were higher in national parks than on highways, even though there was less traffic.

Vegetated Roadsides and Medians

Roads essentially create a break in the environment and allow flowers to grow that might attract insects. For example roads through forests create meadow-like areas that attract pollinators. In deserts the runoff along roads can create an oasis of pollinator plants. In some cases this is positive and better roadside habitat can reduce butterfly road crossings.

In other cases, having plants along the roadside can be a double-edged sword for pollinators. Insect roadkill was twice as high when there was a central vegetated median separating traffic lanes. Bee mortality is greater on roadsides that were made up of lawns compared to roadsides that were meadows.

How to Avoid the Swarms?

Flying swarms are usually either mating or migrating. The reason we used to have so many insects on our bumpers is that they all emerge at a certain time of year, usually only for a few weeks just to mate. These swarms are often near the habitat the insect uses.

Overall, most bug splats occur at night. Like the moth, as well as some flies, mosquitoes, and beetles, they’re attracted to light—and mistake the headlights for moonlight.

Here are a few examples of the most spectacular swarms so you can save yourself some sanity and your car’s paint by avoiding them!

Grasshoppers

Grasshoppers win on sheer size and scale. In May 2014, the US National Weather Service detected swarms of grasshoppers flying over 300 m above Albuquerque.

The swarm was so large, covering the entire city, that the weather service initially assumed that it was a weather front. Only when they saw that the ‘particles’ moved in a non-random way did they realize it must be grasshoppers.

Monarch Butterflies

The most famous swarmer is the monarch butterfly (Danaus plexippus). In late summer or early autumn, this insect utilizes tailwinds to travel over 2,000 miles over around 75 days.

The butterflies rest in overnight clusters within trees. In the morning, they either resume if the prevailing wind is agreeable, or search for nectar if it is not.

The methods used to maintain this migratory flight course are unclear, though geomagnetism and polarized light orientation have been proposed.

Mayflies

The mayfly, which belongs to the aptly named Ephemeroptera (from ephemeral for short lived) order, presents a phenomenal display of mass copulation for only a few hours after emergence.

Swarming can be observed over or near water and shorelines on warm summer evenings. Swarm size and height is species dependent, though the swarm itself can be both low flying and broad, containing up to 200 individuals.

Mayflies are attracted to light, so their numbers are especially high near streetlights. That means they accumulate on the roads at intersections, and combined with the squishing afforded by passing vehicles, they can form greasy slicks. Sometimes the swarm uses a busy asphalt road as a marker, succumbing to the traffic.

Popular places to find mayfly swarms are always near water since their nymphs live their before hatching out.

Susquehanna River in Pennsylvania. The Hexagenia mayfly hatch is a large-scale event that happens every year in mid to late June, with the swarms being so impressive that you can hear the wings crashing.

Lake St. Clair in Michigan. The Hexagenia limbata mayfly swarms in the southeastern corner of Michigan's Lower Peninsula are also massive and can be quite overwhelming.

Ebro River in Spain. Each summer, millions of mayflies rise from the Ebro River, converging on the medieval stone bridge of Tudela, in northeastern Spain. Attracted by lamplights along the bridge, the insects swarm the area in a fluttering cloud of white wings. Many of the mayflies that gather above the Ebro River end up laying their eggs on asphalt instead of the water—which mirrors the river’s surface because of the light.

Midges

Midges (a type of fly) can be either biting or non-biting, but either way when you see a midge hatch, you might want to go the other way. One story I heard in graduate school was a lake in Africa where so many midges emerged that people would get smothered. I’m not sure it this is true but there are some places where millions of midges come out at once.

Lake Myvatn (Iceland). Lake Myvatn is known for its biblical plague-level midge swarms.

Bear River Migratory Bird Refuge (Utah). This refuge has been noted for its midge swarms, which are a food source for birds.

Termites and Ants

I used to rent an old wooden house and every spring the outside would be crawling with flying termites. Needless to stay I didn’t stay in that house very long.

Termite swarms, also called swarming termites or alates, are a sign of a termite colony reaching capacity and attempting to establish new colonies. These swarming termites emerge from their nests in large numbers to find mates and start new nests. They fly for only a short time before landing and losing their wings

Most subterranean termites swarm in the spring and summer. Drywood termites and some subterranean species swarm in the late summer or fall.

Swarming often occurs on warm, calm days, especially after rainfall. Most wait until a day following a rain shower when the weather is overcast and winds are under 6 mph.

Swarming termites are often mistaken for flying ants. They have a stockier body and straight antennae, unlike ants, which have a thinner body and bent antennae

Ant swarms, also known as ant swarming or nuptial flights, are a natural phenomenon where large numbers of winged ants, including queen and male ants, emerge from a colony to mate and establish new colonies. This usually happens in late spring and early summer, and is triggered by warm temperatures, bright sunlight, low winds, and high humidity

Ants tend to fly earlier in urban areas than rural areas, probably because temperatures are generally warmer in urban environments, known as the urban heat island effect. They are known to swarm at just the wrong time, like at Wimbledon. There are years when flying ants plague players during their matches, causing so much disruption it makes the news.

Once ants have mated, the role of the males is over. The mated queens quickly chew off their own wings and begin looking for a suitable site in which to nest and set up a new colony.

Mosquitoes

I studied mosquitoes for my Masters and often wouldn’t let my wife at the time kill a mosquito before identifying it. Needless to say we are no longer together.

Orkin just posted its 2025 list of the top cities for mosquitoes based on treatment data from the metro areas where Orkin performed the most mosquito control services from April 2024 through March 2025, in residential and commercial areas.

In 2025, the cities experiencing the largest mosquito swarms include Los Angeles, Chicago, New York, Atlanta, and Detroit. Los Angeles has been at the top of the list for four consecutive years. California also sees a high number of mosquito swarms, with five cities (Los Angeles, San Francisco, Sacramento, San Diego, and Fresno) making the top 50 list.

Mosquitoes swarm where there is water. Hurricane Laura in Louisiana left so much standing water that thousands of mosquitoes hatched out. There were so many mosquitoes that they sucked hundreds of cattle dry.

In Alaska, some joke that mosquitoes are “Alaska’s state bird,” but the pesky insects are becoming no joke. These arctic mosquitoes emerge as the snow melts in the millions. They can actually drain the blood from a caribou, leaving it for dead.