The yard treatment the USDA tested against ticks
Cedarwood oil (cedrol) applied to surfaces repelled 80–94% of black-legged tick nymphs in USDA-funded peer-reviewed testing. Treat the yard, deck rails, and fence lines where ticks actually live — and they never get close enough to need DEET.
- USDA chemist Fred Eller's cedarwood-coated string blocked ants for two years straight.
- Applied to surfaces, cedrol disrupts ticks' pheromone receptors so they can't locate a host.
- 80–94% repellency on black-legged tick nymphs — the species that transmits Lyme.
- Outdoor Shield uses Juniperus virginiana — the same species in the USDA studies.
A USDA chemist noticed something
Fred Eller is a chemist at the USDA’s Agricultural Research Service in Peoria, Illinois. He’s spent years studying naturally derived compounds for agricultural applications.
One day he noticed: ants never crossed cedar mulch.
He ran an experiment. He tied a string coated with cedarwood oil around a pole leading to a sugar-water solution. For two years, not a single ant climbed it. When the string rotted and fell off, the ants came back.
That observation turned into a peer-reviewed study published in Environmental Entomology — one of the most respected journals in the field. And what the study found goes well beyond ants.
What the tick research actually showed
In controlled laboratory testing, cedarwood oil applied to surfaces repelled 80 to 94 percent of black-legged tick nymphs — the species responsible for transmitting Lyme disease. The active compound is cedrol, a sesquiterpene that disrupts the tick’s pheromone receptor system so it can’t locate a host.
At the highest doses tested, cedrol killed 100% of the black-legged ticks crossing treated surfaces. The mechanism was confirmed across all four hard tick species tested in a follow-up study published in PMC in 2022. The USDA also tested fire ants — a 50% cedrol solution achieved 100% repellency in field conditions.
This isn’t folk wisdom or grandmother’s remedy. It’s federally funded peer-reviewed entomology research.
Treat where ticks live, not your skin
DEET is a personal repellent — you spray it on yourself before walking into tick country. It works. Nobody is arguing otherwise.
Outdoor Shield is something different. It’s a perimeter and surface treatment for the place ticks actually live: yard edges, fence lines, leaf litter, deck rails, the woodland border where the lawn meets the trees. Spray those zones and the cedrol does what the USDA showed it does — ticks won’t cross treated surfaces, and they don’t make it to the part of the yard where your kids and dog are.
The cedarwood oil in our Outdoor Shield formula is sourced from Juniperus virginiana, the same species used in the USDA studies. It’s in the bottle specifically because of this data.
DEET handles you. We handle the yard.