Acorn Crops Forecast New York Lyme Disease Risk

A 35-year New York forest study links red oak acorn abundance to later increases in Lyme disease tick nymphs.

Updated on Nov. 8, 2026 in Forecasts

Red oak trunk and scattered acorns on a leafy autumn forest floor, with a small white-footed mouse half hidden in the litter. — Abundant red oak acorns in New York forests predict a rise in white-footed mice and infected Lyme disease ticks about two years later, a 35-year study found. AI Illustration. Upload story photo >

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Richard Ostfeld and colleagues published a 35-year study in Proceedings of the National Academy of Sciences USA showing that abundant red oak acorns boost white-footed mouse populations, which in turn raise tick nymph numbers. The findings suggest Lyme disease risk can be forecast almost two years in advance.

Why it matters

Lyme disease infection depends largely on how many tick nymphs are near people outdoors, so an early signal from acorn production could help residents prepare. The research points to a predictable chain from forest food supply to mouse populations to tick numbers.

The study spans 35 years of forested areas in New York State and shows acorn abundance can signal Lyme risk almost two years before tick nymphs peak. The extraction does not quantify how large the resulting tick increase is, nor how forecasts would be operationalized.

The players

Richard Ostfeld

Ostfeld is an ecologist at the Cary Institute of Ecosystem Studies in upstate New York who led the 35-year study on acorns, mice and ticks.

The details

Abundant red oak acorns in fall increase winter survival of white-footed mice, which boom the following summer. Those mice are ideal hosts for tick larvae and very efficient at transmitting the Lyme bacterium, so more mice produce more infected nymphs the next year.

Fall: abundant red oak acorns support winter survival of white-footed mice.
Following summer: white-footed mouse populations boom.
Following year: tick nymph numbers increase.

Forecasts

The 35-year record from New York forests, run through the Cary Institute of Ecosystem Studies, turns a multi-decade ecological dataset into a near two-year warning for Lyme disease. It shows how long-term field monitoring can move from explaining ecosystems to predicting public health risk.

Residents who spend time outdoors in New York forests should use tick checks and repellent during high-nymph seasons. Watching for public health advisories in years following heavy acorn crops can help people plan outdoor activity.

The takeaway

A heavy acorn year is an early warning that more infected ticks may appear about two years later. Checking for ticks after time outdoors remains the most practical step residents can take.