Published on 02/18/10

Turf battles reduce pesticide use, pit wasps against crickets

By Cheri Abraham

Every spring as lawns start to green up, lawn perfectionists begin their vigilant watch for the onslaught of pests waiting for fresh dinner. Along with pests like armyworms and grubs, mole crickets cause significant damage to southeastern lawns.

Mole crickets first came to Georgia in the 1900s, and they’ve been terrorizing turfgrass and lush lawn lovers ever since. Now, wasps that homeowners rarely see are terrorizing the crickets. One of their natural enemies, the mole cricket killer wasp, known scientifically as Larra bicolor, is native to their homeland in South America.

Entomologists in Florida and Georgia imported these wasps into the United States. They now live along the Gulf Coast and throughout the South. A keen-eyed observer may find them scanning the turf in lawns or golf courses, constantly studying the surface.

That’s bad news for crickets but good news for homeowners, golf course superintendents and lawn care professionals.

Solitary mole cricket killer wasps are not easily spotted. They are medium sized and seldom group in noticeable numbers, except when they are feeding on nectar. They don’t have nests, so there is no risk of disturbing their colony and getting stung. These wasps tend to be calm and take off when they feel threatened.

For the most part the wasps feed on nectar. However, female wasps also hunt for mole crickets.

The hunt begins when a female wasp searches the turf for mole cricket burrows. When she finds one, she enters and then chases the mole cricket to the surface. Above ground, this chase continues as the mole cricket tries to evade the wasp by hiding in the grass or by trying to enter another mole cricket burrow.

At the end of the chase, she stings the mole cricket. She then lays an egg on the cricket while it is immobilized. This egg hatches in about 4 to 12 days, and the larva remains attached on the outside of the mole cricket and feeds on it.

Within a month, it becomes a fully grown larva ready to pupate. By this time, only the tough external portions of the mole cricket remain. In about 4 to 6 weeks, a new wasp emerges.

But, remember, mole cricket killers need more than crickets to feed on. They also need nectar. Homeowners can help their lawns and the wasps by planting flowers they can feed on.

One of the best nectar sources for these wasps in the U.S. has been shrubby false buttonweed. Unfortunately, it’s a weed in Southern turfgrass and is not a good choice. Star cluster, also known as star flower or Pentas lanceolatus, is a common landscape flower that shows promise as a good nectar source and is probably the next best option to help sustain these wasps.

If you see these wasps in your lawn, think of the ways they help us – by controlling mole crickets and reducing the pesticides we put into nature.

Cheri Abraham is a graduate student with the University of Georgia College of Agricultural and Environmental Sciences Department of Entomology.

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