Crickets on the move

Allison Remcheck

Professor studies behaviors of these mysterious insects


Credit: Carl Schierhorn

Watch out, the crickets are coming.

Literally millions of cannibalistic crickets migrate every summer.

Mormon crickets – a species of a katydid – travel in herds of about 12.5 miles long and 6.2 miles wide throughout the western part of the United States. From above, they look like one, creepy-crawly being. They’re green east of the Rocky Mountains and brown to the west. And the farther west the crickets are, the more aggressive they get.

The Mormons thought they were a plague sent by God, said Patrick Lorch, professor of biological sciences, and one of only a few Mormon cricket researchers in the world. Lorch, funded by the U.S. Department of Agriculture, studies the crickets’ migrations in Utah, Colorado and Idaho. His main challenge is to figure out why the crickets form such large groups and why these groups migrate.

Lorch said the Mormons believed God finally sent seagulls to eat the crickets and save them and their crops from destruction.

And then the birds threw up.

This is because Mormon crickets eat chemicals in their food as a defense against other predators, Lorch said.

Lorch’s job is to study the crickets’ behavior and their pack mentality.

“If they are by themselves they are very likely to be eaten by a predator,” he said.

But the cricket has a higher chance of being safe within a big band, because their predators are “likely to be full,” Lorch said.

“If you’re cricket number 2,000,000 in this band, you’re really not going to get much food,” Lorch said.

Mormon crickets are one of the best examples of the “selfish herd,” Lorch said, meaning the animals are in a group because it is safer for them, not to help others. By studying the crickets’ selfish habits, Lorch said scientists are able to relate this information back to other animals – including humans.

“We assume the reason humans have a behavior is the same reason animals have a behavior,” he said.

Because of this, it becomes an example of survival of the fittest and the injured are eaten first. Lorch said he and his colleagues placed a healthy cricket in a bucket with an injured cricket to see what would happen.

“These guys are very predatory,” Lorch said. “We actually showed that they can eat an entire cricket in an hour.”

Lorch also studies the mating behavior of the crickets. When female crickets die rapidly, a female takes on multiple male partners – a rare occurrence, but one also observed among different groups of humans, Lorch said.

Allison Toth, junior zoology major, watches video of crickets on a plate to map their movement. The crickets were filmed for two minutes, using different combinations of fed and hungry crickets.

“Some were deprived of food for no hours and some were deprived 24 hours,” she said. “We want to see how food depravation and density affect movement.”

As Toth maps the crickets, she checks their social behavior for patterns. The crickets don’t like to be approached by other crickets, she said, and sometimes if one cricket approaches another cricket, the movement pattern will change.

“Some of them just don’t care (if they are approached),” she said, “and others are much more skittish.”

Mormon crickets cause the most problems for farmers, who try to stop the crickets’ destruction of their crops with pesticides.

“It’s not usually put up in large enough quantities to harm humans directly,” Lorch said, “but it can kill all the other insects . the predators that eat these animals probably all die. I would imagine they’re bad for everything at some level.”

This summer, if he gets enough funding from the USDA, Lorch may take two Kent State students west with him. In his lab, students are already looking at videos of the crickets and mapping their coordinates as they move, while observing the ways the crickets interact with one another.

Lorch said 12 crickets at a time are fitted with radio transmitters. Their signals are detected during the migration, and maps are plotted with a GPS to predict the movement of the crickets – mainly to help farmers with their crops.

The crickets have been known to travel a mile within a day, a big accomplishment for a tiny insect, Lorch said.

The crickets are also prey for other animals, including lizards, birds and snakes.

“Almost everything bigger than them eats them,” he said.

But for now, Lorch is concentrating on tracking the crickets’ movement.

“My job is to find out about the biology and make it better known,” Lorch said. “What we’re trying to do is build a model for the way these things move.”

Contact science reporter Allison Remcheck at [email protected]