Horticulture Hotline 05/10/21
By Bill Lamson-Scribner
Wasps, flies, fire ants, mosquitoes – oh my!
Digger wasps are continuing to multiply in numbers in the Lowcountry. At Possum’s we use to get a few complaints in localized areas, now the numbers seem to be on the rise. One faithful reader of the ‘Horticulture Hotline’ sent me a 14-page letter describing the progression of damage to her yard. I saw an old friend in the grocery store and a conversation that would have dominated by fishing stories or stories about old times was dominated by ground bees. The presence of wasps is intimidating and unsafe.
Digger wasps start out as just a few holes in the yard. The holes are where the adults lay their eggs. In the spring, the young emerge. In the fall these wasps are now adults and they dig new holes and lay eggs for the following spring. In a very short time period, you can go from having a few digger wasps to thousands. All these holes can ruin your turf areas and the wasps make it less enjoyable to be in the yard.
Most of these wasps are predatory feeders. They eat grubs (should manage for moles and potential turf damage), small flying insects and ground dwelling insects (mole crickets, grubs). The wasps sting the prey to death, then bring the dead prey back to the wasp’s hole (nest), then lay an egg on it so the young have an instant food supply when it hatches.
All control should be done at dust or at night when the wasps are in their hole. You need to plan on several applications of products to manage this pest. Since the wasps eat insects in your yard that you should be managing to certain thresholds, going after the wasp as well as their food source should benefit you greatly (like the mole). Since the wasps like subsurface insects, Sevin would be a good product to start your management program. Who knows you might kill a fire ant or the nasty rascal the chinch bug as a bonus?
If you just have a few holes, D-Fence Dust is a great product. At night treat in and around the hole. When the wasp land near the hole and go into the hole, the dust gets on them and kills them. The wasps also transfer the dust between themselves. Some people will also “plug” the hole. At Possum’s we sell the plugs, but you could possibly use something from around the house. Be sure to turn off the irrigation and check for rain. After you use the dust, it would be best for the area to stay dry for the night.
If you have many of these uninvited guests, DeltaGard G or Turf Ranger could be used across the whole area. Remember they fly, so getting your neighbors involved is crucial. These products need to be watered in to get to the target. Turf Ranger recommends ½ inch of water. Water the product in slowly so the product soaks into the ground, and does not run off into a non-target area. Apply these products when you first see the wasps and until they are gone, waiting at least one week between applications.
EcoVia is a National Organics Program compliant product that is labeled for wasps and other small flying insects (mosquitoes – yeah). EcoVia is safe to use around water, kids, and pets. Consider using EcoVia in your product rotation.
When treating always wear dark clothes and have a can of wasp freeze on your person. Digger wasps did not get there overnight, and they are not going to go away overnight.
Ants seem to be coming to the surface despite the dry weather, and I’m seeing mounds everywhere. Grilling, here come the nasty flies. No telling what they landed on before they landed on your dinner, especially if you have a dog. Wasps in bushes, in the corners of your doors, in your grill, on your gutters, on your outdoor furniture, everywhere! Have you heard that familiar sound by your ear that a mosquito makes recently?
Always read, understand and follow product label. The product label is a Federal Law.
