ACC Experts: What causes the yearly cricket invasion in Austin

By: Mark A. Shepherd, Ph.D., QEP,  Department Chair for Earth and Environmental Sciences

Armies of small, dark, creeping crickets have spread throughout the city of Austin. In some areas of the city, their populations have reached seemingly apocalyptic levels. One café in midtown Austin temporarily closed its doors rather than have customers pass crunchy invaders. The University of Texas, San Antonio dispatched people to “treat, clean, and monitor” the cricket situation. The crickets are not just on the ground blocking entrances but have gone vertical, climbing support pillars and walls, even massing on rooftops.  

Why is this happening? The easy, but the disappointing answer is: it’s happening because it has always happened. During much of the year, many insects move among us in low concentrations. However, there are months when one or more insect species climb, crawl, and squeeze en masse from dark hidden places into the light spaces where humans live. 

In June, the notorious and much hated June bugs arise to decimate flower gardens. These tiny, plump tanks with wings are in reality several different species of beetle that have similar characteristics.  A couple of years ago, giant walking sticks invaded rural parts of the Hill Country, and spidery harvestmen frequently show up in such large numbers that they can make a structure look hairy.

Now, we are dealing with a population explosion of field crickets. Heavy rains during the spring are blamed for helping to spark the invasion, but it’s not clear if rain is an indicator or a cause of the dramatic increase in population. Several other weather and non-weather factors come together to form the perfect conditions needed. Soil temperatures are likely significant in helping speed development of nymphs into adults. It could also be that the emerging onslaught is a cyclical phenomenon, slowly and imperceptibly increasing each year until one year they break forth in staggering displays of fertility. Even our hungry birds can’t eat this many crickets, which could be another reason that insects emerge in large numbers.     

Very little real damage results from the mass of descending crickets. They don’t bite, sting, or carry diseases of great concern. Other than the smell of dead, decaying insects, the fouling of pools and fountains, and the cost to clean them up, the crickets represent a highly visible, but temporary nuisance. 

The news is not all bad. This October we may witness one of the largest monarch butterfly migrations in quite some time. Hundreds of thousands of butterflies heading south for the winter may pass through the area. By then, the current cricket plague will have been forgotten.