You've probably lain awake at night wondering why God created cicadas - those noisy insects that buzz like motorcycles on hot, summer days.

A couple of Utah State University researchers have one possible explanation.The critters play a quiet role in the formation of hardpan or "duripan" soils in the West.

In a study area in the Goose Creek drainage of Utah's northwest corner, soil scientists Al Southard and Tom Furst have identified a thick layer of fossil cicada burrows overlain and preserved by a later volcanic deposit. The exposed burrows look like little elongated bags.

"The burrows represent silica cementation," Furst said. "The cicadas develop on plant roots and backfill their burrows with silica."

So what, you ask?

Furst believes the cemented burrows may prevent water and root penetration. That's the good news.

The bad news is that the burrowing activity may also open up the soil. Available phosphorus is greater in the burrows, and in the long run, the cemented burrows retard soil erosion.

So whether the effect of the cicadas is "good" or "bad" is debatable, Furst said.

The debate has been going on for some time; the insects aren't new to nature.

Furst said cicadas have been around for at least 7 million years, but have been keeping a low profile.

Most of a cicada's life is spent underground as an immature, eating roots. The immatures are less than an inch long and are built like backhoes, with wide flattened front legs.

They are still eating away in the areas of northwestern Utah, the Snake River plain of Idaho and northern Nevada where Southard and Furst are looking at several aspects of the chemistry and development of thick layers of hardpan soils.

"One four-winged saltbush we excavated had 14 cicadas on its roots," Furst said. "But they're difficult to keep alive and observe in the laboratory."

Southard and Furst's research is supported by the U.S. Soil Conservation Service, the Bureau of Land Management and the Utah Agricultural Experiment Station.