It’s surprisingly easy to end up learning a lot about insects. Unfortunately, we really need to, as they keep spreading and finding new ways to be a nuisance, not to mention, making life a bit more unpleasant.
Consider houseflies. They love the warmth, and, aside from being annoying, they serve as what some might call “mechanical vectors” for diseases. Essentially, they walk through trash and then traipse around your kitchen, leaving behind germs like salmonella and who knows what else on your countertops.
Then there are longhorned ticks, which first appeared in the U.S. in 2017. Strangely, these ticks can reproduce without males; the females just clone themselves. Male ticks are so rare, they’re thought to be accidental. Naturally, this raises alarm bells across the U.S.
In a more bizarre twist, the saliva from these ticks can trigger a serious allergy to things like ice cream and burgers—a true sci-fi scenario.
And we can’t forget about the New World screwworm.
With factors like climate shifts, weather changes, and even the abundance of acorns (yes, really) dating back to colonial land use, it’s clear that these pests are multiplying.
From a health perspective, there’s no denying that these insects are becoming a bigger issue. According to the CDC, reported cases of diseases spread by vectors doubled from 2005 to 2019, with ten new pathogens identified in the last 17 years.
“Not that I want to make anyone anxious, but this feels like just the tip of the iceberg,” said a tick expert from Connecticut, noting an increase in tick populations and diseases in the state. “They’re mostly found in coastal areas right now, but as temperatures rise, they’ll likely spread inland.”
Ticks are, in fact, the main culprits for vector-borne diseases in the U.S., although globally, mosquitoes are even more problematic thanks to malaria (which we’ll touch on later).
In the U.S., ticks can transmit over a dozen diseases, with Lyme disease being the most prevalent. Experts alarmingly describe the rise of tick-borne illnesses as “explosive,” extending well beyond Lyme.
“Lyme, babesiosis, and anaplasmosis are all rising dramatically, and there’s no sign of stabilization,” said a leading disease ecologist from the Cary Institute, who tracks these troubling trends.
As many as 476,000 people annually in the U.S. might be diagnosed with Lyme disease, and while treatment with antibiotics is generally effective, if left unaddressed, it can lead to long-lasting issues like severe headaches or even irregular heartbeats.
Babesiosis can lead to flu-like symptoms and red blood cell destruction, affecting thousands yearly, though considerably fewer than Lyme. Anaplasmosis can cause serious conditions, including respiratory issues and potentially death; it impacted about 7,000 individuals in 2023 in the U.S.
Powassan virus, while rarer, has also been on the rise, resulting in cases of severe brain inflammation.
Interestingly, this year has seen emergency room visits for tick bites reach the highest point in seven years, according to CDC data, especially prevalent in the Northeast but also rising nationwide.
Part of the problem? Ticks are expanding their territories.
“There are definitely areas where people grew up not having to worry about ticks, and that’s changing,” noted an expert from Penn State.
Blacklegged ticks, which carry the bacteria responsible for Lyme, have significantly increased their foothold across the U.S. over recent decades.
While climate change plays a role in their spread, it’s not the only factor. These ticks are moving not only into cooler areas that have become more welcoming due to climate change but also into warmer southern territories.
“It’s a complex situation,” said the entomologist, pointing out the interplay of climate and landscape changes over the last two decades.
Deer populations, having rebounded dramatically after facing near extinction from hunting and deforestation, don’t carry Lyme-causing bacteria themselves but do transport ticks. Meanwhile, a particular mouse species that does harbor the culprit thrives in areas disturbed by human activity—like suburban sprawl.
Also, let’s not forget chipmunks—they can carry ticks as well.
While tick-borne illnesses are undeniably on the rise, there’s still some variation in their severity from year to year and place to place.
The projected number of ticks fluctuates significantly based on the previous summer’s mouse populations, which correlate strongly with acorn abundance from the prior fall.
A good crop of acorns one year can lead to a higher mouse population the next, increasing the chances of ticks biting them, which in turn heightens chances of them biting humans. Some regions faced a particularly tough year in 2025 due to this cycle.
Recent findings from Connecticut have confirmed the CDC data, showing a significant increase in tick prevalence, with more ticks testing positive for Lyme disease-causing bacteria this year compared to historical averages.
Roughly 40% of blacklegged ticks tested this year have been found to carry Lyme, compared to 32% historically. A sizable portion also test positive for babesiosis and anaplasmosis.
Additionally, about 10% of ticks carry multiple pathogens, complicating diagnosis and treatment.
Other tick species are not falling behind in spreading illness either; the lone star tick, for instance, is responsible for alpha-gal syndrome, an allergy to meat and dairy products, gaining ground across the U.S. and particularly depending on white-tailed deer as hosts.
Gone are the days when this allergy was a rare concern; with as many as 450,000 people in the U.S. potentially affected, areas like Martha’s Vineyard are increasingly seeing residents shifting to vegan diets.
Thanks to its friendly climate and abundant wildlife like deer, Martha’s Vineyard is also dealing with an influx of the self-cloning Asian longhorned tick, which is being monitored closely.
The biologist working there noted the uncertainty surrounding these ticks’ potential public health impact, admitting they make him anxious.
In their homeland, longhorned ticks can bite humans and transmit types of encephalitis, but in the U.S., they’ve mostly emerged as agricultural pests, now documented as far south as Georgia and west to Missouri.
Though ticks are the primary disease carriers in the U.S., mosquitoes equally pose significant threats as their ranges expand.
The U.S. eliminated malaria in 1951, though localized cases have occasionally arisen since. Currently, the primary mosquito-related health issues are West Nile virus and dengue fever.
West Nile, which affects about 2,000 people annually in the U.S., is seeing an early start this season, while dengue has caused thousands of locally acquired cases, particularly troublesome in Puerto Rico.
Aedes mosquitoes can transmit serious viruses like chikungunya, Zika, and yellow fever, and their range is consistently expanding at an alarming rate.
In fact, they’re estimated to be moving northward at roughly 150 miles a year, worsened by climate change.
Meteorological factors—like temperature and precipitation—greatly affect mosquito populations, which entomologists expect will surge this year due to a warm, wet spring.
Flies might also be particularly prevalent this year, as weather patterns are contributing to their resurgence. Meanwhile, the New World screwworm, identified as a flesh-eating fly, may also thrive in the changed climate, taking advantage of the environment.
Lastly, in the Southwest, scorpions are anticipated to create more disturbances as they seek shelter indoors due to monsoon conditions.
The silver lining is that there are ways to mitigate these bug-related issues.
Experts suggest wearing EPA-registered repellents for ticks and mosquitoes. An added layer of protection involves treating your clothing with permethrin, which is effective but harmful to insects.
Also, creating an environment around your home that’s less inviting to pests—like removing standing water and managing leaf litter—can make significant differences in keeping bugs at bay. This tactic also helps deter scorpions. Moreover, fixing any screen holes and gaps in your home’s exterior is a practical measure.
As the bug problem grows, science is advancing too. Pfizer has announced it’s seeking approval for a Lyme disease vaccine, the first new one in two decades, while initiatives are underway to develop pills to eliminate ticks post-bite.
For alpha-gal syndrome, doctors are increasingly resorting to the allergy drug Xolair to reduce severe allergic reactions. There’s also some evidence that a specific type of acupuncture may be beneficial.
Looking towards the future, some researchers are even investigating the genetic modification of mice to prevent them from carrying Lyme-causing bacteria, while others have resorted to eliminating deer populations on isolated islands as a more straightforward approach to curb the disease.
Regardless, experts emphasize that personal protection remains the most crucial factor in combating these issues.
“The most important thing that people can do is personal protection,” said the Connecticut tick expert. “Nothing can compare to that.”
