A trip in the car this summer could provide a lesson in splatology as well as some sightseeing.

Daniel Marsula, Post-Gazette Click illustration for larger version. What's the splatter? A red splat means the bug is female (and most likely a mosquito); mostly it's female bugs that bite. The largest splats are typically large female moths or butterflies. The smallest splats are biting midges, known in the South as "no-see-ums." Splats that glow are fireflies.

Just ask Mark Hostetler. He drove 11,000 miles around the country with a net strapped to the top of his '84 Honda Accord to conduct his research. He also visited Greyhound stations at night to examine the front of more than 50 buses.

His mission: to examine bug splats.

Dr. Hostetler, 40, an entomologist at the University of Florida and self-proclaimed "splatologist," is the one to ask if you're looking for an explanation of that flying road kill on your car windshield.

A red splat is probably from a female bug, most likely a mosquito, because that's the gender that does the most biting.

The smallest splats that leave a dot of wet sap are probably biting midges, tiny flies known in the South as "no-see-ums."

Most insects fly 4 to 5 feet off the ground -- perfect striking distance by cars. Butterflies are a common victim because they're attracted to the yellow reflector lights on the highway, he said.

You're also likely to get more splats at night, when moths are flying toward the headlights, or after a rainstorm.

A few years ago he wrote the book "That Gunk on Your Car: A Unique Guide to Insects of North America," which, he said, really aims to get people more interested in the study -- and appreciation -- of insects and how habitats vary across the country.

"Every third bite of food you eat has been pollinated by an insect," he said. "Fruit, veggies, even nuts. You wouldn't have them without the service of insects."

But Bill Todaro, entomologist with the Allegheny County Health Department, believes that the book on highway splats should have been written decades ago.

"Maybe in Florida there's still a lot of them, but in most of the rest of the country the bug population has been reduced drastically," he said. "You hardly ever get bugs splattered on your windshield."

The reason: "There's overbuilding, our sprawl," he said. Now in his late 50s, Mr. Todaro recalled as a child growing up in this region having the family car covered with bug splats. "Today, you hardly see that."

Yet John Rawlins, head of invertebrate zoology at the Carnegie Museum of Natural History, believes the difference in what people saw in the 1950s and '60s and today in bug splats is more complicated. He agrees with Mr. Todaro that the diversity of the bug population has declined, but not so much the density.

Dr. Rawlins speculates that the change in vehicle design -- from the boxy Ford Fairlanes with upright windshields to the more aerodynamic teardrop cars introduced in the '70s -- partly accounts for the decrease in splats on the windshield. "The bug gets into the laminar airflow and goes across the vehicle. It never has contact with the vehicle."

Also, land along high-speed highways are more manicured and are farther from dense bug habitats than they were years ago, which also accounts for the decline. "This has drastically decreased the bugs that wander out in the splat zone," he said.

Introduction of invasive species over the years also has reduced the mix of bugs. "But overall, we still have a rich, healthy diverse community of native bugs," he said.

In Pennsylvania, that includes 59 species of mosquitoes. Other bugs you'll encounter here -- at least in mid-May through July -- are rebounding populations of mayflies, a sign that rivers and streams are getting cleaner.

Although mayflies have only a 24-hour life cycle -- with their primary goal of squeezing in rounds of sex -- these 2-inch bugs with triangular sail-like wings can provide some sizable splats on your windshield if the highway runs along a stream or river.

Honeybees, too, are coming back, Mr. Todaro said. Over the last two decades, Varroa mites that hitchhiked on fruit from Asia and Britain have killed off 90 percent of the nation's honeybees. But he's starting to get calls about wild swarms of honeybees again being spotted in the area.

If your trip takes you south this summer, you'll probably run into swarms of lovebugs, a type of fly that is a particular nuisance to motorists. They're attracted to car exhaust, which mimics the smell of decaying organic matter where lovebugs lay their eggs.

It was lovebugs that got Dr. Hostetler started on this unusual research in the first place. While driving along Florida's Interstate 75 in May 1993, he pulled into a gas station. A guy from out of state, who could barely see out of his windshield because of the all the bug splats, asked him what all this stuff was.

"I gave him a three-minute spiel," he said.

Most prevalent in May and September, these black bugs fly in copulating pairs (hence the "lovebug" nickname for plecia nearctica) and their splats can literally cover a windshield and car grill. Originally from Central America, they're working their way up the East Coast and have been spotted as far north as North Carolina.

The lovebug swarms reach their highest concentration between 10 a.m. and noon each day and rarely fly after dusk, so if you want to avoid these, travel at night.

They're so bad that car washes in some states may charge $4 to $5 more in the summer. If they're not removed right away, the fluid from the remains can damage paint. Build-up on the radiator also can cause the car to overheat.

Some motorists spread a light film of baby oil over the front of the hood and grill to prevent lovebugs from sticking so much. Dr. Hostetler has teamed with Prestone, which offers a wiper fluid called "Bug Wash" to promote his book and the study of insects.

Fortunately, motorists -- at least up here -- don't see Dr. Hostetler's favorite bug, which is the cockroach. (Some species do fly.)

As pets, he keeps an aquarium of the exotic Trinidad wood and death's head cockroaches, both 4 inches long.

Now those are splats we definitely want to avoid.