Insect swarms a natural occurrence

Have you ever had to run to the car to avoid flying gnats? Perhaps you sit on the patio with an umbrella to avoid beetles and their larvae, which are falling from the trees. Maybe you have driven through Nevada when thousands of oily, squished Mormon crickets have caused oil slicks on the road. A couple of weeks ago, our local offices of University of Nevada Cooperative Extension received numerous calls about black bugs that were showing up by the thousands around businesses, homes and even the hospital. It turns out that these were seed bugs.

Insects, by their nature, swarm. Whether it is cicadas, elm leaf beetles, Mormon crickets, termites, ants, false chinch bugs, seed bugs or other insects, swarms are annoying, disturbing, challenging, and to some, terrifying.

Every year, residents call to ask us if swarms of flying insects they are seeing are termites. Most often, the insects they are seeing are winged king and queen prereproductive ants migrating to start new colonies. Sometimes, they are termites. Every few years, Mormon crickets arrive, often by the thousands. Some years, cicadas hit the area hard, with their droning hum making an incessant white noise.

Swarming is part of the mating process of certain social insects. Insects leave the colony to mix their genes with other colonies' genes, reproducing healthier progeny. Swarming is triggered by temperature, wind, humidity and day length.

Does global warming cause severe outbreaks of unusual insects? Global warming isn't causing insect swarms, but changing weather patterns do affect precipitation, temperature and other climatic factors. These factors influence how well plants grow, as well as which plants develop and thrive. Certain insects need particular plants in order to survive. If rain and snow is above normal one year, plants may produce plentiful food supplies the following spring that allow mating insects to produce multitudes of hardy young. They, in turn, also reproduce. On the other hand, when foliage is excessive, there is also ready fuel for wildfires. The fires may burn out populations, reducing insect swarms the following growing season. When the winter or spring is warm, more overwintering adults, young and eggs may survive and reproduce. However, extreme cold can wipe them out.

Swarms generally are short-lived, and chemical controls are often ineffective. You can spray one day, and have hundreds of pests show up again the next day. Often, the good old shop vacuum is a good control tool. Simply vacuum up the insects and drop the canister contents into a bucket of soapy water. As in most gardening endeavors, patience pays.

For more information on controlling pests and gardening, contact me, (775) 887-2252 or skellyj@unce.unr.edu, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu. "Ask a Master Gardener" at mastergardeners@unce.unr.edu

n JoAnne Skelly is the Carson City/Storey County Extension Educator for University of Nevada Cooperative Extension.