From your description—a 4-inch-high tower of mud balls with a central hole—this is almost certainly a chimney made by a cicada killer wasp or a similar solitary wasp, or it could be an antlion trap if you’re in the right region, but given the height and structure, a mud-dauber wasp nest seems most likely. Here’s why:
1. Likely Culprit: Mud-dauber Wasps
- Appearance: Mud-daubers create small, tubular nests of mud.
- Structure: Cylindrical tower, sometimes with multiple “cells” for larvae.
- Hole in center: Often the opening where the adult emerges or enters.
- Height: 4 inches is consistent with some mud-dauber species.
- Behavior: They collect mud and form tiny balls, stacking them to make nests.
2. Alternative Possibilities
- Cicada killer wasps: Build burrows in soil, usually larger, and less likely stacked mud.
- Ants or termites: Sometimes make mud mounds, but rarely with a single central hole and distinct mud balls.
3. Safety Tips
- These wasps are generally non-aggressive unless disturbed.
- Observe from a distance; avoid stepping directly on it.
- If you want to relocate or remove, wait until adult activity decreases (usually late fall), then gently dismantle.
If you want, I can also show you a picture of what a typical mud-dauber nest looks like, so you can confirm if it matches what’s on your lawn. Do you want me to do that?
