It’s quite easy to unintentionally gather extensive knowledge about insects. Regrettably, this is necessary as they continue to proliferate, devising new methods to annoy us and generally diminishing our quality of life.
Consider houseflies: They flourish in higher temperatures and are not merely a nuisance; they also act as what entomologists term mechanical vectors for diseases. In simpler terms, they traverse through refuse and then onto your kitchen surfaces, leaving behind salmonella and various other harmful microorganisms along with their minuscule footprints.
And then there are longhorned ticks, which first appeared in the United States in 2017 and possess the unusual ability to clone themselves. Female ticks can produce thousands of duplicates; occurrences of male ticks are exceedingly rare and believed to be accidental. It’s no surprise that they are a growing threat in the U.S. as well.
In a particularly bizarre scenario, the saliva of ticks can induce a serious allergy to foods like ice cream and hamburgers.
Furthermore, we have the New World screwworm to consider.
Due to factors like climate, weather, the abundance of acorns (yes, it’s true), and land-use decisions dating back to colonial times, the situation regarding bugs is indeed worsening.
The Rise of Arthropods
From a health perspective, it is clear that insects are becoming an increasingly significant challenge. According to data from the US Centers for Disease Control and Prevention, reported incidents of vector-borne diseases have doubled from 2005 to 2019, and new pathogens keep coming to light — a total of 10 identified in the last 17 years.
“I’m not trying to incite unnecessary worry, but I believe this is just the tip of the iceberg,” remarked Dr. Goudarz Molaei, a tick expert from Connecticut, who has observed a surge in tick populations and disease cases in his state. “Currently, they are primarily found in coastal areas, but as the trend of warming persists, they’ll likely spread from coastal regions into inland areas over the next few years.”
Ticks are indeed the main source of vector-borne diseases in the U.S., while globally, mosquitoes are more prominent culprits due to the widespread impact of malaria. (Mosquitoes are worsening here as well, but more on that later.)
In the U.S., ticks can spread over a dozen different diseases, with Lyme disease being the most prevalent among them. Experts lamentably describe the rise in tick-borne illnesses as “explosive,” extending beyond just Lyme disease.
“Lyme disease, babesiosis, and anaplasmosis are all significantly increasing, with no signs of a slowdown,” stated Dr. Richard Ostfeld, a disease ecologist and senior scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York, who tracks such troubling trends.
An estimated 476,000 individuals in the U.S. could be diagnosed and treated for Lyme disease each year, based on insurance claim data, as many cases might go unreported. While it can be effectively treated with antibiotics, especially when detected early, it can lead to long-lasting issues such as joint pain, severe migraines, and irregular heart rhythms if left untreated.
Babesiosis can lead to flu-like symptoms and the destruction of red blood cells. It impacts thousands of Americans annually, though significantly fewer than Lyme disease, as per the CDC. Anaplasmosis can also result in severe health complications, including respiratory failure, bleeding issues, organ failure, and even death, although it can also be treated with antibiotics if detected early. It affected around 7,000 individuals in the U.S. in 2023.
Another tick-related illness, the Powassan virus, has also been on the rise, though it is quite rare: As of 2025, it was reported to have affected 76 individuals across the country. It can also be serious, leading to encephalitis, or brain inflammation.
This year, emergency room visits related to tick bites in the U.S. have reached their highest levels for this time of year in the past seven years, based on CDC data, although they did not hit as high a peak as in some previous seasons. The highest numbers are seen in the Northeast but are elevated across all regions.
Ticks Expanding Their Territory
One part of the issue is that ticks are extending their range.
“Ticks are definitely appearing in areas where people previously didn’t have to worry about them,” stated Dr. Erika Machtinger, an associate professor of entomology at Penn State.
Blacklegged ticks, responsible for Lyme disease, as well as the pathogens causing babesiosis and the bacteria leading to anaplasmosis, have expanded into twice as many counties between 1996 and 2015.
We cannot solely attribute their spread to climate change, although it does play a role. The ticks are moving not just into previously colder regions that are now becoming more hospitable, but also into warmer areas.
“The situation is complex,” Machtinger explained. Climate is a factor, but so are “landscape changes in the U.S. since the early 2000s.”
Deer populations, which have seen their own surge after being nearly decimated in certain U.S. areas due to deforestation and over-hunting, don’t carry the bacteria that cause Lyme disease, but they do transport ticks. White-footed mice, which do harbor the bacteria — charmingly named Borrelia burgdorferi — flourish in areas disturbed by human activity, according to Ostfeld. And people are increasingly proficient at disturbing natural habitats through suburban development.
Chipmunks, in yet another unforgettable fact, can also serve as carriers.
Acorns as a Warning Sign
While the trend of tick-borne diseases in the U.S. is undeniably on the rise, the severity varies from year to year and region to region.
The most reliable indicator of the tick population each year is the number of white-footed mice present the previous summer, Ostfeld indicated to USdaily. “And the best predictor of mouse populations,” he stated, “is the quantity of acorns that fell from oak trees in the previous fall.”
A high acorn yield in one year correlates with a large mouse population the following year, which increases the likelihood of baby ticks biting a mouse and surviving long enough to bite humans.
This cycle led to an especially challenging year in certain areas in 2025.
Additionally, observations from the field this year in states like Connecticut corroborate the CDC’s findings on higher-than-normal emergency department visits for tick bites, according to Molaei, a medical entomologist at the Connecticut Agricultural Experiment Station’s Tick Testing Laboratory.
The data they are gathering this year, both from tick submissions for pathogen testing and during field surveys, is “significantly higher” than last year and any previous year since 2017, Molaei noted.
Furthermore, a greater proportion of ticks are testing positive for Lyme-causing bacteria this year: approximately 40% of blacklegged ticks submitted for analysis, compared to a historical average of 32%. Between 12% and 14% carry babesiosis parasites, while 7% to 8% harbor bacteria responsible for anaplasmosis.
“In recent years, we have observed an increased prevalence of infection with these pathogens, particularly babesiosis,” Molaei added.
Up to 10% of ticks tested are infected with two or three pathogens simultaneously.
“This undoubtedly creates significant challenges for diagnosis and treatment,” he stated.
Other Tick Species on the Rise
Other tick species are also expanding their range and causing increased problems. The aforementioned allergy to foods such as ice cream and hamburgers is known as alpha-gal syndrome, which is transmitted in the U.S. by bites from the lone star tick.
While they are primarily found in the Southeast, lone star ticks have been moving northward and advancing from coastal regions. They depend particularly on white-tailed deer as hosts. Their saliva contains a sugar molecule present in mammalian products that can induce an allergy to red meat and, in some cases, dairy.
The CDC estimates that up to 450,000 individuals in the U.S. may suffer from alpha-gal syndrome. This issue is escalating in regions like Martha’s Vineyard, a popular summer destination off Cape Cod, Massachusetts, where a growing number of residents have had to adopt vegan diets.
Martha’s Vineyard is particularly conducive to ticks due to its climate and overpopulation of hosts like deer. Island biologist Patrick Roden-Reynolds reported finding two Asian longhorned ticks on the island in 2023, marking the first time he identified them there. Last year, he collected 50.
“At this moment, we are uncertain about the potential public health threat posed by these ticks,” he stated. However, their presence is concerning.
Within their native habitats, longhorned ticks do bite humans and can transmit certain types of encephalitis, Roden-Reynolds explained, but in the U.S., their primary concern has been as a pest affecting agriculture. The U.S. Department of Agriculture has noted their presence as far south as Georgia and as far west as Missouri.
The Most Dangerous Animal
While ticks contribute significantly to disease in the U.S., mosquitoes are also a serious threat — and they are expanding their ranges as well.
The U.S. eradicated malaria — the most lethal mosquito-borne threat worldwide, which earned mosquitoes the title of the deadliest animal on Earth — in 1951, although there have been occasional localized cases that have emerged.
The more pressing mosquito-borne issues in the U.S. currently include West Nile virus and dengue fever, which are transmitted by two distinct mosquito genera.
West Nile, carried by mosquitoes of the Culex genus, impacts roughly 2,000 individuals annually in the U.S. and results in about 130 fatalities. This season has had an early and troubling start, according to the CDC. Dengue, spread by Aedes aegypti and Aedes albopictus mosquitoes, caused approximately 4,000 locally acquired cases in the U.S. in 2025, particularly impacting Puerto Rico.
Aedes mosquitoes can also spread viruses causing chikungunya, Zika, and yellow fever, and they have been broadening their distribution. The first Aedes aegypti in California were identified in 2013, and they have been migrating northward since. The first specimens in Idaho, which was previously outside the mosquito’s territory, were discovered in August.
In general, Aedes aegypti are estimated to be advancing northward in the U.S. at a rate of approximately 150 miles per year, as per research from the Yale School of the Environment, and climate change could accelerate their spread in the long run.
Mosquito populations are also influenced by weather patterns, according to Dr. Jim Fredericks, an entomologist and senior vice president of public affairs at the National Pest Management Association.
“Pest populations and their biology are closely linked to factors such as temperature and precipitation,” he stated. Additionally, his organization predicted an especially buggy season across the U.S. this year, with a mild and wet spring leading to increased mosquito populations early in states from Texas to Mississippi, and tropical storms creating conditions for mosquito outbreaks from standing water in the Southeast.
Flies, which are known to be mechanical vectors for disease, might also be more problematic this year due to climatic conditions across much of the U.S. Furthermore, the flesh-eating New World screwworm — which is a fly in its adult stage — may also benefit from both climate and weather changes as it re-establishes itself in the U.S. after 60 years. They can lay their eggs in wounds as small as tick bites, leading to a disturbing cycle of one bug benefiting from another.
Lastly, the Southwest is anticipated to face an especially troublesome year for scorpions — yes, they are arthropods too! — as they, along with other arachnids like spiders, are driven indoors by monsoon rains.
Combatting the Insects
The positive news is that we can take measures to prevent the problems caused by insects.
For ticks and mosquitoes, it is advisable to use insect repellents registered with the Environmental Protection Agency repellents. Additionally, treating clothing and footwear with permethrin, a repellent safe for humans but harmful to insects, provides an extra layer of defense.
Maintaining your home environment to deter insects can also have a significant impact: removing standing water, which serves as a breeding ground for mosquitoes, and clearing away leaf litter, where ticks prefer to reside, from frequently used areas. This is also good advice for keeping scorpions away: relocating wood piles, trash, and debris from around the house, and repairing any gaps in screens and openings in the home’s exterior.
As insects continue to evolve, scientific progress is also being made. Pharmaceutical giant Pfizer has announced its intention to seek approval for a Lyme disease vaccine, which would be the first such product available in two decades if granted by the U.S. Food and Drug Administration. Additionally, efforts are in progress to develop alternative methods of safeguarding against ticks, such as a pill currently undergoing clinical trials that aims to eliminate ticks after they bite, thus preventing the transmission of pathogens.
For alpha-gal syndrome, the tick-induced meat allergy, medical professionals are increasingly utilizing the allergy and asthma medication Xolair to mitigate the risk of severe allergic reactions. There are also suggestions that a specific type of acupuncture may provide relief.
Additionally, there are more innovative approaches being explored, such as genetically modifying mice to prevent them from carrying the bacteria that cause Lyme disease, a potential project on Nantucket Island. Alternatively, an island in Maine eliminated its entire deer population. It’s remote enough that deer cannot swim there (which they are capable of doing in some locations) and repopulate. As a result, the incidence of Lyme disease on the island has diminished.
However, all these methods are secondary to taking proactive steps to protect ourselves, as emphasized by experts.
“The most crucial thing individuals can do is to ensure personal protection,” said Molaei. “Nothing can surpass this.”
