Ticks Down, Mosquitoes Up

If you’ve managed to get on the trails super early or super late in the day during this heat wave, it’s no news that mosquitoes are VERY active right now in this heat. The good news is that the tick activity decreases dramatically.

Check out this excerpt from an amazing online public health newsletter Your Local Epidemiologist. Started during COVID, this factual data-driven email newsletter (or substack) covers what you need to know (including another of today’s pieces on cyclospora). It is well worth your subscription to the email/substack (and donation if you are able).

Excerpt from Your Local Epidemiologist newsletter, July 14, 2026

Katelyn Jetelina and Marissa Donnelly, PhD

“Ticks are backing off

We’re well on our way down for tick season. Activity tends to drop off as we move deeper into the heat of summer.

Source: CDC; Annotated by Hannah Totte at Your Local Epidemiologist

Why? Ticks are prone to drying out, so in peak summer heat they retreat into moist, shaded leaf litter rather than questing (climbing grass to grab a host), which reduces host-seeking activity even if the tick population hasn’t shrunk. This dip also lines up with the tick life cycle: nymphs, responsible for most Lyme transmission, peak in late spring/early summer, then quiet down in the hottest weather before adults pick back up in fall.

Mosquitoes taking over

As ticks recede, mosquitoes take over and with them, the rare diseases they can carry. The most common one in the U.S. is West Nile.

Peak mosquito season is still about a month out, but the CDC is already flagging an unusually early surge in West Nile virus (WNV) activity this year. They have flagged 48 cases across 23 states detecting the virus, which is more than five times the historical average for this point in the season.

Source: CDC. Annotated by Hannah Totte at Your Local Epidemiologist

What this means for you: Most people infected with WNV never even know it because ~80% have no symptoms. But older adults and those who are immunocompromised can develop serious neurological illness. Start being consistent with using an EPA-registered repellent (with DEET or picaridin), dumping standing water around your home, and using screens at dusk and dawn.

Your Local Epidemiologist (YLE) comprises a team of experts, ranging from physicians to immunologists to epidemiologists to nutritionists, working together with one goal: to “translate” ever-evolving public health science so that people are well-equipped to make evidence-based decisions. The YLE suite of newsletters reaches over 475,000 people across more than 132 countries. This newsletter is free to everyone, thanks to the generous support of fellow YLE community members.” 

Stay cool and safe out there and see you on the trails.