Groundhog Under Deck: Why Repellents Fail and How to Humanely Evict

Persistent digging under a deck despite ammonia, mothballs, traps, and a radio indicates a groundhog (woodchuck), not a fox. Repellents rarely work—animals tolerate them when motivated by shelter or food. Relocation is often illegal, inhumane, and just moves the problem.

Effective, Humane Solution: Exclusion with a One-Way Door

1. Trench-screen the deck: Attach 1/4-inch galvanized hardware cloth to the structure, extend 18+ inches outward at a 90° angle underground to prevent digging under.
2. Install a one-way door over the entry hole so the groundhog can leave but not re-enter. Do not attempt if young are present (typically before July).
3. Verify vacancy using the "paper-hole technique" (icwdm.org) before sealing permanently.

Other Options (with caveats)

• Harassment: Repeatedly backfill holes—may take weeks.
• Trapping & euthanasia: Legal in some states; requires proper technique and disposal. See groundhog control guide.
• Fumigants: Dangerous; sulfur-based can cause fires; aluminum phosphide (Phostoxin) requires a license. Not recommended for non-professionals.

Never seal an active den. Groundhogs rarely threaten pets but can undermine foundations. For complete guidance, visit icwdm.org.