Field Notes: Insects

~by Jim Eagleman

The ground was powder dry and bare; the last rain had been weeks before. We stood motionless and dazed as the professor rambled on. The humidity that morning had risen to 80 percent and we knew we were in for another scorcher. A few students fanned themselves with the handout.

“High temperatures and high humidity create great conditions for insects,” he said. “While we don’t do well in this heat, the mosquitos and ants love it.”

A forest ecology class at the university’s new field station was one of several I enrolled in that June. With no summer job prospect and a chance to take some required classes, I moved into an old farmhouse at the field station. Bunk beds, a small, communal kitchen, and one bathroom made for sparse conditions. Still, I had looked forward to this class and the others for weeks.

“You will appreciate how well a forest functions if you add the important role of insects,” the professor said. “I won’t make entomologists of you this summer, but we will certainly view insects in a more positive light than what you previously thought.”

Our schedule for the next few days was to visit the property’s many habitats, located on the upper bluffs of the Mississippi River in western Illinois. There were hilltop prairie remnants, deep forest ravines, and many streambeds that fed into the river. Our hikes to each place allowed us to discuss and speculate, with a lot of stopping to inspect leaf litter, tree bark, and plants. Insects played a major role as plant and animal relationships were examined.

Several times I thought the class should be renamed. Instead of forest ecology, it should rather be called “bugs of forest and glade.” We saw pollinators visit flowers, leaf miners chisel their way along plant veins, and ants carry leaf cuttings to their underground home. A yellowbilled cuckoo flew from a small cherry tree with webbing, the forest tent caterpillars a part of its diet.

Insects viewed in a more positive light than what we thought? The professor might be right.

A box turtle stopped us, and a reference was made to its cold-blooded lifestyle. The professor reminded us that all insects are also cold-blooded. As temperatures rose under the canopy, humid, still and motionless, sweat trickled down my arm. A stink bug moved rapidly along a tree limb—a lot faster than one I saw earlier. The cold-blooded reptile sat motionless, relying on its surroundings for food, shelter, and comfort level. It may not have been that different from the life of a bug.

We moved into a field overgrown but once grazed by livestock. A large mound appeared in the distance. We walked through tall grass and soon caught the stench of a dead animal. A cow had died, never retrieved by the farmer, and was now bloated from extreme heat. Standing downhill from the carcass, we could peer into the open body cavity. We saw some movement. Out crawled a mother ’possum looking a bit disturbed, her babies further back in a nest of cow hair and dried stomach contents. Maggot flies swirled as she exited, and she stopped to snap at a few flying around her head. Wasps, scavenger beetles of an indeterminable lot, and ants scurried about as she left.

She returned later to her home, nursery, and food pantry. The insects helped further decomposition and provided food for predators, we were reminded. The ’possum was the “star of the show,” but insects also played critical supporting roles in this drama.

On a trip back to campus a swarm of June bugs smacked against my windshield. These fat, clumsy flying beetles chose this time to appear in big numbers. Turning on the wipers, a frothy smear was no match for washer fluid. I had to stop and clean the glass. “Opportunists” was the term the professor used; the conditions happened to be just right for this population explosion.

But nothing compared to the wave of cicada emergence later that summer. Predictions of a healthy annual cicada appearance, along with the periodic 13-year hatching, made this coemergence a big “must see.” Cicada biology made the front page of the local paper, and we were primed to witness this glorious event.

With their noisy and peculiar lifestyle, cicadas can actually help trees. Small limbs where eggs are laid eventually die and drop to the ground creating a pruning effect. The nymphs that hatch burrow below ground and move while feeding on roots, aerating soils. Birds and squirrels feast on cicadas during their mass emergence, but large numbers are likely to outstrip any capacity to control them. Surplus dead cicada bodies rot and add organic fertilizer to forest plants.

Inter-relationships of plants to animals, insects to plants, and insects to animals, while a foundation to ecologic understanding, continue to reveal dependencies. These relationships may be easy to see, or appear subtle, minute. This is a reliance we cannot disregard. These associations can be a great mystery, challenge, and hope. The more we know, the more we need to know. Sound science and biology remain key. May we all view insects in a more positive light.