A screen porch became a favorite addition to our house. Built off an upstairs bedroom on the east side, it has large eaves to keep out the rain, screens around three sides, a screen door to an outside deck, some comfortable chairs and a fold-up bed. The screen porch affords tree-house views across the valley to the east and south.
What I really enjoy about the screen porch is being able to hear what goes on out in the woods at night.
Deer snort, foxes yap, coyotes howl, owls hoot, and raccoons tussle. There’s nearly always something making noise at night in our woods. We once had a black-crowned night heron roosting up the hill that sounded like a strangled cat. That took some early morning forays with a big flashlight to find out what it was.
This time of year, it’s the crickets and katydids that I really enjoy. Their repetitive constant rate chirps are soothing and put me to sleep. Because they are cold-blooded critters, their activity is affected by temperature, chirping faster in warmer temperatures and slower when cooler.
Black field crickets
There are 25 species of grasshoppers and crickets in Wisconsin. Black field crickets (Gryllus pennsylvanicus) are common around here. They live in a variety of habitats in eastern North America north of Florida.
The males call for females (stridulate) by moving ‘scrapers’ of the left forewing across a row of teeth-like structures on the underside of the right forewing. The male cricket makes a three-note trilling song that is answered by a simpler two-note female song.
Biologists have studied the relationship between ambient temperature and the rate of cricket chirps. These vary with species, but for the field cricket, you can estimate the approximate air temperature in degrees Fahrenheit by counting the number of chirps in 13 seconds and then adding 40.
Field crickets are omnivorous, eating plant matter and small invertebrates of many kinds. They live in grass and leaf litter. As the weather cools, they often move inside people’s houses. Field crickets can damage fabrics, paper and leather. Their chirps can sound really loud inside a house. They can sense the vibrations of people walking and stop chirping when approached, making them hard to find.
Birds, raccoons, skunks, red foxes, snakes, and turtles all eat crickets. I used to capture crickets for use as bait for panfish. The energetic chirping by male crickets makes them more vulnerable to predation, a tough trade-off for each individual.
After mating, female field crickets deposit up to 400 eggs in the soil. The nymphs hatch out in 12 to 25 days, looking like tiny adult crickets. They eat ravenously, molting eight times before reaching the adult stage. This simple metamorphosis rarely is completed because so many nymphs are preyed upon. The average lifespan of a field cricket is only one week.
Field crickets are ecologically important members of grassland and forest communities. They consume plant matter, leaving fecal pellets that are easily decomposed by bacteria and fungus, recycling nutrients. They eat the seeds of many invasive plant species like crabgrass and ragweed, helping reduce the abundance of those plants.
Now that the leaves are turning color and the nights are getting cooler, I’ve noticed a decline in the rate of cricket chirps without getting out a stopwatch. I’m spending less time at night on the screen porch and retreat into the bedroom when the temperature drops into the 40s and the crickets go silent.