CT Tick Season 2026 Could Be Among the Worst; New Haven County at High Risk

Connecticut Scientists Warn 2026 Tick Season Could Be One of the Worst on Record

Connecticut researchers are warning that the 2026 tick season could be among the most severe in recent memory, with New Haven County identified as one of the highest-risk areas in the state for invasive tick species.

Goudarz Molaei, a medical entomologist and research scientist at the Connecticut Agricultural Experiment Station, said climate change is the driving factor. "The most important factor is the climate change," Molaei said, noting that rising temperatures are enabling tick populations to expand their range into the Northeast and allowing non-native species to establish themselves in regions where they previously could not survive.

Warmer winters have increased tick survival rates, while above-average snowfall in some years has provided an insulating layer that shields tick populations from freezing temperatures. As spring temperatures rise, those populations can emerge in greater numbers.

New Haven County Among Areas with Highest Invasive Tick Concentrations

Invasive tick species are a particular concern in New Haven and Fairfield counties, which have recorded some of the highest concentrations of non-native tick populations in the state, according to CAES research. The invasive species thrive in wooded areas and tall grasses — habitats that are common across Connecticut's suburban and semi-rural landscape.

The Connecticut Agricultural Experiment Station has documented the continued range expansion of multiple tick species in the state, driven in part by warming conditions. In 2025, CAES reported the first evidence in the U.S. of an invasive longhorned tick infected with Ehrlichia chaffeensis, a bacterial pathogen, signaling that the range of tick-borne diseases may be expanding alongside the tick population itself.

Diseases Carried by Connecticut Ticks

The black-legged deer tick remains the primary carrier of Lyme disease, which is the most commonly reported vector-borne illness in Connecticut and nationwide. But tick bites can transmit additional diseases that pose serious health risks:

• Lyme disease: Caused by Borrelia burgdorferi; most common tick-borne illness in the state
• Anaplasmosis: A bacterial infection that can cause fever, headache, and muscle aches
• Babesiosis: A parasitic infection of red blood cells; can be severe in older adults or those with weakened immune systems
• Powassan virus: A rare but potentially life-threatening viral infection with no specific treatment

Lyme disease in the United States has more than doubled over the past 20 years, according to federal disease tracking data.

Prevention Recommendations

Experts at CAES and state health authorities recommend the following precautions during tick season, which in Connecticut typically runs from early spring through late fall:

• Check for ticks thoroughly after all outdoor activities, including hiking, gardening, and walking in grassy areas
• Wear long sleeves and pants when in wooded or tall-grass areas, and tuck pants into socks
• Use EPA-registered insect repellents containing DEET or permethrin
• Apply veterinarian-approved tick prevention treatments to dogs and outdoor cats
• Remove any attached ticks promptly using fine-tipped tweezers; early removal reduces disease transmission risk

Residents with pets should be particularly vigilant. Tick-borne infections in animals can become chronic and may require long-term treatment.

The Connecticut Agricultural Experiment Station continues to monitor tick populations and disease prevalence across the state. Updated surveillance data is expected to be released later in the spring.

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