COLUMN: Field crickets – here, there, everywhere

THE NATURE OF THINGS COLUMN
By: 
Michele Olson
Jones County Naturalist

   What’s that constant chirping sound?

   Summer is a season of many sounds! Whether you’re playing at a local park, walking a wooded trail, or enjoying a slow moment on your patio, the chirps of summer are all around. One of the more common summer chirpers is the easily-identified black field cricket.

   The black field cricket is a rather large shiny black cricket. Adults can reach up to an inch in length, although most of the ones you see in early and mid-summer crawling through the grass or hiding under a stone are immature nymphs.

   Crickets belong to the order Orthoptera, meaning “straight-winged,” suborder Ensifera, meaning “sword-like” referring to their long, curved ovipositor, and family Gryllidae also known as “true crickets.” They are very interesting when you take a closer look.

   Black field crickets spend the winter as eggs which the female laid one at a time in the late summer and fall soil with her long, sword-like ovipositor. If you look at an adult cricket you can tell the difference between male and female quite easily. Only the females have the long, curved ovipositor protruding from the end of their abdomen. Sometimes the ovipositor is mistaken for a stinger.

   Cricket eggs hatch in late spring to early summer, coinciding with when you will notice tiny immature crickets, called nymphs, hopping about in grassy areas. These nymphs look like adults but are much smaller and do not have wings. As they eat and molt, their wings grow larger and more developed. After approximately 90 days they will reach maturity with fully developed wings. These adults are often the ones that accidentally wander into our homes. They are in a race against time to mate and lay eggs before they succumb to predators, old age, or the freezing temperatures of the first hard freeze.

   The loud chirping, that can drive some of us loony, is done mainly by the males. This is his way of romantically singing to all the female crickets within hearing distance. Crickets chirp by rubbing their wings together. A “file and scraper” combination found on their front wings produces chirps when the wings are rubbed together at a 45-degree angle. Amplifying mirrors, circular sections of wing membrane that are stretched tightly, increase the volume along with the space between the stridulating cricket’s raised wings creating an echo chamber.

   Crickets hear using “ears,” tympanum, located on their front legs. A swollen part on their front legs, near the “knee,” holds a tiny “drum skin” inside a hollow area that allows the cricket to hear. Next time you catch a cricket take a close look to see a cricket’s ears.

   Since crickets are nocturnal, moving around at night, they do most of their singing at night after the sun sets but they can chirp at any time of the day. During the day they can be found hiding or resting under boards, rocks, or in dark corners of garages or basements. Like other insects’ crickets are more active in warmer weather and will chirp more often as the temperature increases. Want to do some fun cricket weather forecasting? To convert cricket chirps to degrees Fahrenheit just average the number of chirps in 14 seconds, then add 40 to get a rough estimate of the temperature. Give it a try!

   Crickets are scavengers and feed mainly on organic material as well as decaying vegetation, fungi, and seedling plants. Sometimes considered common household pests, crickets inside homes may chew on carpet, material, and furniture.

   To prevent crickets from entering your home make sure to seal all cracks, gaps, and holes around the foundation, siding, doors, and windows. Homeowners should also keep vegetation and debris away from house foundations. By limiting access and habitat you should be able to deter most of the crickets that might accidentally call your house home.

   Did you know that crickets have even been welcomed and kept as pets in some cultures? In a few Asian countries, crickets are sometimes kept in homes as a symbol of good luck. In some places, cricket’s chirps have special meanings. A loud cricket means money is coming your way and you must not kill or evict it. We all wish that were true!

   To visit a great resource for learning more about Iowa’s crickets, or to report crickets you have in your neighborhood, visit the iNaturalist website at https://www.inaturalist.org/guides/14496.

 

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