Liris beatus (Hymenoptera: Sphecidae) is an unusual wasp that occasionally becomes a pest in Texas homes. Known as the cricket-hunter wasp because of its habit of catching and feeding crickets to its offspring, these wasps are common outdoor insects.
Cricket-hunter wasps are ½ – 5/8 inches long, dull black in coloration, with grey or dusky-colored wings. They spend much of their time searching for crickets, which they attempt to sting, capture, and transport live to their nest. After a cricket victim has been subdued and carried to suitable shelter, the female lays on it a single egg. After hatching, the larva begins feeding immediately on its paralyzed cricket prey. One cricket probably provides enough food for a single wasp to develop.
Cricket-hunter wasps can be found actively climbing up and down walls of bathrooms and other living areas. They can appear indoors year-round, but are most common in late summer, fall, and during warm spells in the winter. Infestations can be persistent and annoying. Though not normally aggressive, when prompted these insects can occasionally sting.
So what are these wasps doing in homes? In nature, female cricket-hunter wasps establish nest sites in holes in the ground, such as rodent burrows. In urban areas, where natural nesting sites are rare, these wasps take advantage of man-made cavities in the walls of buildings. Good sites include weep holes in brick facings or other openings in walls or under house foundations. A single female may deposit several crickets, each with egg, in a nest site. In addition, other female wasps may share the same site, building cricket stashes up into the hundreds or possibly thousands.
When the cricket hunter larva matures, a process that may take several weeks or months, they pupate and wait for suitable conditions to occur to emerge as an adult. When conditions are favorable, the adult wasps will emerge and attempt to exit from the nest area. If nests are located in walls, or under the foundation of a home, some wasps may emerge indoors through gaps around windows, air vents, or similar wall openings.
Because many crickets may be provisioned within a wall void in the manner described above, dozens or hundreds of wasps may emerge into a home, giving the false impression that a large colony, like a bee’s nest, is present in a walll or attic.
It’s difficult to prevent adult cricket-hunter wasps from emerging into living areas of a building once nesting sites have been established in a wall or under a foundation. If openings through which wasps enter living areas can be located, they should be sealed. Adult wasps can usually be safely killed with a fly swatter, or else captured and released outdoors to continue their cricket hunting activities.
The best solution for a cricket hunter wasp infestation is prevention. Start with a careful assessment of possible entry points outside the home or building. Seal any outside openings you find that might provide access to wall voids. Ventilation holes, such as weep holes, should be screened with 1/8th inch or finer mesh screen. Cracks and gaps should be sealed with expanding foam, mortar, or other appropriate material.
Besides openings in walls, look for areas of soil subsidence or sandy soil that shows evidence of burrows. Such areas should be filled with soil or fine gravel and, where appropriate, covered with landscape cloth or plastic and mulch to discourage further burrowing.
In cases of heavy wasp infestations, non-insulated wall voids may be treated with pesticide aerosols or dusts. Treatment of insulation-filled, exterior walls is not likely to be helpful. Sealing and caulking of all possible points of entry into the home is the preferable solution.
You can help
Little is yet known about cricket hunter wasps as indoor pests. If you are outside the Dallas-Fort Worth area and have wasp infestations fitting the description in this fact sheet, the author would be interested in obtaining samples of the offending insects and any observations about its behavior. Please consider leaving a comment in the box below, or contact Michael Merchant via email. Samples of the insects themselves, or good digital images are useful. Specimens should be preserved in ethyl or rubbing alcohol with the location and date collected. Your help is greatly appreciated.
For more information
For more information about stinging wasps see the Extension publication E-239, Wasps, Yellowjackets and Solitary Wasps. For more information about arthropods, check out the Texas A&M Entomology Website at http://insects.tamu.edu/.
Michael Merchant, Ph.D., Professor and Extension Urban Entomologist, Texas AgriLife Extension Service.