How to Eliminate Underground Wasp Hives
Learn how to safely combat wasps and other insect pests that burrow in the soil.
Ground bees and wasps do lots of good for the garden and landscape, which is why it pains us to the core when they decide to nest in our family’s most frequented outdoor living areas. Pests can be most troublesome when they’re in the grass or in between our patio stones; above ground. We typically don’t like to disrupt them unless it’s completely necessary, but because our sandy soil is like a magnet for easy digging, we find their snuggly little lairs all over our yard. They do not like lawnmowers, nor swinging hammocks, or anyone in their immediate vicinity, FYI.
When it’s possible, we try and keep their nests in tacts. Bees and wasps help with garden pollination, after all, and we need them around to some degree. We love the bees! To encourage them to build nests above ground rather than underfoot, some experts will advise you to exercise prevention by soaking your grass thoroughly – all season long – because it’s harder for the ground bees to dig in dense, saturated soil. But when that method doesn’t work, what should you do?
Before you go straight for the poisonous sprays (and yes, they work), consider these alternative techniques for ridding your backyard of pesky wasps and bees that nest underground:
Cover With Diatomaceous Earth
A very soft powder called diatomaceous earth is actually made of crushed fossilized remains called silica. While soft to the touch for humans, this powder is often compared to “little shards of glass” against the bodies of insects. Its abrasive nature will not only damage the wings of the pests, but it’ll gradually kill any other insects that come in contact with it, and with time, treat the whole hive.
Dust it generously atop and inside any visible hole that certainly contains pesky ground wasps, and as they come and go, they’ll come into contact with the powder.
If you dump a 1/2 cup into the ground hole at nighttime (when the insects are “home” and less active) and then cover the hole with a flat rock, you will surely see a difference in activity during the next day. The diatomaceous earth does need to be reapplied after rainfall, or every few weeks if the insects return.
Treat With Soap and Water
At nighttime (again, when the insects are in their hole and less active) cover the hole carefully. A screen or a piece of landscaping fabric works well for this, as the goal is to cover the hole so that the pests can’t escape, but water can still flow in. Landscaping pins, scrap pieces of lumber, or extra pavers will all be helpful at keeping the fabric in position and escape routes to a minimum.
Use a blade to cut a small slot into the top of the material over the hole – it’ll help the water flow in fast, without giving the pests an easy spot to escape.
Mix water and dish soap into a one-gallon container. Alternatively, you can squirt dish soap into the cut in the fabric, and then follow up with a blast of the hose. The soap affects the wasps' ability to fly, the fabric will trap them, and the water will drown out the hive.
Additional Alternatives to Consider?
This wasp trap from an upcycled wine bottle is a trap I made several years ago. Keep it maintained with fresh sugar water (1-to-1 ratio of water and sugar diluted into a simple syrup) and you’ll keep the pests at bay, though it may not be enough to kill the whole hive.
Build Bee Hotels
To invite solitary bees to make their home in a specific location, such as nearby your wildlife-friendly garden, consider building them a bee hotel. This article explains their purpose and showcases designs for your inspiration.