The grasshopper took precautions to protect her offspring.

First, she dug a hole. Into the underground chamber she poured a frothy liquid along with the eggs. Like spray foam insulation, the goop will harden, plugging the hole — sealing its dwellers away from the outside world and its dangers.

Not so. Somewhere along the way, a parasitic wasp hitched a ride on the grasshopper’s wing. She injected her own eggs into the grasshopper's before the liquid casing could harden — transforming the protective envelope into a trap.

The wasp larvae emerge before the grasshoppers, feeding on their biological soup. Call the strategy lucky, cunning or degenerate, but parasitism is one of the animal kingdom’s most common lifestyles.

"Almost every insect has their own parasite, or two or three, or a dozen-some. Some parasites have their own parasites," said Norman Johnson, an entomologist and director of the Triplehorn Insect Collection at Ohio State University. "You do the math."

About 40 percent of animal species are body-hijacking, blood-sucking, flesh-eating, disease-carrying parasites — and parasitoid wasps are among the most diverse and fascinating exploiters, experts say. Despite their abundance and ecological value, though, they remain grossly understudied.

Consider this: pup lovers can choose from about 340 dog breeds. Scientists have discovered and described 90,000 parasitic wasp species, but believe there could be well over 500,000, Johnson said.

Scientific Wild West

Entomology, on the whole, remains a scientific Wild West, said Andrew Forbes, an evolutionary biologist at the University of Iowa.

"Insects are probably the most diverse group of animals," Forbes said. "I always thought there weren’t many animal species left to be named."

New estimates indicate that there are about 5.5 million insects, of which 1 million species have been named: suggesting 80 percent remain undiscovered, according to a 2017 study published in the Annual Review of Entomology.

"Most insects are small and don’t have a direct impact on people," said Ohio State insect collection curator Luciana Musetti.

In contrast, officials and researchers have devoted extensive time and resources to studying conspicuous insects. There's a reason we know a lot about charismatic bugs — colorful butterflies, iridescent beetles and fruit-pollinating honeybees — as well as despised critters such as crop pests and disease-carrying mosquitoes and ticks.

For example, various government agencies and universities spent years studying the Laricobius nigrinus beetle before introducing it in an effort to curb an invasive, hemlock-killing pest, said Tom Macy, forest health program administrator for the Ohio Department of Natural Resources Division of Forestry.

Harnessing insects as insecticides is a popular strategy for controlling widespread pests, Macy said, but it requires thorough research beforehand.

From pollinating crops to decomposing waste for us, wild insects provide at least $57 billion annually in ecological services to humans, according to a 2006 study.

But a small network of entomologists wonders about the fate of other insects — the ones we’ve never laid eyes on and which may not be much bigger than the period ending this sentence.

"We don’t often notice them, so they go unnoticed," Forbes said.

‘Boiling hot’ frontier

Parasitoid wasps have devilish strategies for laying their eggs on or inside other living creatures.

Tarantula hawk wasp larvae burrow and feast their way through a tarantula's abdomen — saving vital organs for last — before bursting out of the dead spider as an adult. Another type of parasitic wasp grub sucks orb weave spiders dry and hijacks their webs to anchor a cocoon of its own.

One even injects a "neurotoxic cocktail" to turn cockroaches into zombie slaves.

"It’s warfare. It’s what pushes evolution: attack and defense," Musetti said.

Despite their impressive and ruthless tactics, parasitoid wasps are not immune to the tide of human-caused extinction sweeping the planet. Invertebrate abundance has declined about 45 percent over the last 40 years, according to international research from 2014.

That undoubtedly means, Johnson said, that insect species are disappearing before they're ever observed by humans.

In many ways, Johnson is as rare as the wasps he studies. When he retires, there no longer will be an expert, anywhere in the world, on the 600 wasp species in the Telenomus genus. "I’m sort of an endangered species," he joked.

That’s par for the course in his field, he said. Ohio State's parasitic wasp lab is one of only a handful worldwide that study the Platygastridae family of parasitic wasps. They discover new species all the time.

"Every time you get a sample, there’s a good chance you’ll find something no one has ever seen before, even across the street," Musetti said.

Once collected, samples head to one of six freezers already stuffed with an estimated 1.5 million specimens.

Armed with forceps, researchers sort the bug-filled samples by type: beetles, dragonflies and damsels, flies, hymenoptera (wasps, ants, bees) and so on.

Often, they run into something no one’s ever seen before. Over one five-year period, Johnson said, the lab identified, described and named 468 new parasitic wasp species.

Technological leaps in DNA analysis has helped researchers bolster evidence for the introduction of new species, Johnson said.

In the end, though, labor-intensive taxonomical methods — microscope images and observations about habitat and reproduction, for example — remain the most cost- and time-effective tools for entomological discovery, he said. That means that along entomology’s vast, unexplored frontier, insect researchers are still relative pioneers.

"This is boiling hot compared to other fields where the basic foundation has been laid for decades," Johnson said. "We’re so far from that."

mrenault@dispatch.com

@MarionRenault