The Invasive Ant Species That Can Change an Entire Ecosystem

When goods are shipped into the country, sometimes they are not the only cargo. Sometimes they can bring in unwanted stowaways: invasive species.

Invasive species are non-native organisms that make their way into areas and rapidly reproduce. These organisms have the potential to cause harm to the ecosystem and push out native species. One specific example of an invasive species making a resurgence is Brachyponera chinensis, or the Asian needle ant. This small ant has a painful sting that can cause serious allergic reactions, so it is considered a medically important pest. Although this ant might be tiny, it is a big deal.

They’ve Been Here For A While

This is not a new problem. The Asian needle ant, native to southeastern Asia, was found in North America around 1932 and has been spreading ever since. “They’re problematic because they can infest both natural and disturbed areas, which includes homes,” explains Dr. Katelyn Kesheimer, an entomologist and team lead with Bayer.

What makes them so good at invading is how adaptable they are. Common nesting sites include rotting wood, leaf litter, under rocks, and even inside homes. They are not typically aggressive, but the sharp, painful sting can cause allergic reactions in individuals sensitive to their venom.

Outcompeting the Locals

Asian needle ants are not just troublesome, they are also bad news for native ant species. In areas where they have moved in, scientists have noticed a big drop in native ant populations. Messing with one part of the ecosystem affects everything else, and native ants do a lot of behind-the-scenes work. Some examples include: mixing the top layers of soil (making it more fertile), helping control pests, providing food for other animals, and dispersing seeds.

Many plant species require dispersal by native ants to continue their populations (ant-reliant plant seeds). According to Dr. Kesheimer, the increasing Asian needle ant populations have the potential to displace these native ants, which can disturb ecosystems, particularly forests. They do so by invading the same microhabitats that native ants rely on (like logs and leaf litter). Also, they can be aggressive towards other ants and do not integrate into native ant communities, making it a direct competition with native species.

Aphaenogaster spp.: A Species Being Replaced

These native ants, which are important to seed dispersal in Eastern U.S. forests, are currently being displaced by Asian needle ants. Certain native plants have a mutualistic relationship with these species. The ants carry and bury seeds from parent plants away to other locations, which helps forest regeneration.

With the arrival of the invasive Asian needle ant, Aphaenogaster populations can collapse, and thus those plant species struggle too. The result?

• Reduced seed dispersal
• Forest regrowth slows
• Shift in plant understory (affecting insects, birds, and other wildlife)

Since the Asian needle ants do not disperse the seeds the same way, their ecological output would not replace the native ants, therefore making it vital to support the native species.

The Pain Is Real: How to ID and What To Do If Stung

To identify an Asian needle ant, here are a few things to look for:

• Size (around 3/16th of an inch long)
• Antennae have sharp bends
• Moves fairly slowly and is typically solitary/forages alone or in small numbers
• Near moist shady places or next to buildings

Since they typically do not build big mounds, they can be easy to miss. If you are unsure, snap a photo and contact a local extension office or pest specialist for proper identification.

Post-Sting Instructions

The pain of this sting is similar to that of a bee or wasp sting. Symptoms include burning and maybe a little swelling. After being stung, make sure to wash the sting, then apply a cold compress, and keep an eye on it. However, if you have any other reactions such as feeling dizzy, shortness of breath, or breaking out in hives, make sure to seek medical attention immediately.

“Asian needles can sting and possess venom that can be dangerous to people with allergies to other stings. Those with known insect sting allergies should be cautious,” Dr. Kesheimer warns. Therefore, in these cases, always have an EpiPen nearby.

Tips to Keep Them Out

The best way to avoid stings? Do not let them settle in the first place. Here are a few things that will help:

• Do not let logs or branches sit too close to homes
• Seal cracks and holes in the foundation or siding
• Be cautious with outdoor potted plants/mulch (they can hide in these)

Also, make sure to keep an eye out when outdoors in early spring. Asian needle ants become active a bit sooner than most native ants, giving them a seasonal head start.

So, Why Should You Care (Even If You’ve Never Seen One)

It can be easy to shrug these ants off as no big deal. However, the reality is, these ants have the potential to change entire ecosystems. They show up earlier than other ants, take over quickly, and thus can push vital native species out. In addition, the more they spread, the harder they are to control. Not to mention, these ants are a medical risk for those sensitive to insect venom.

Expert status is not a requirement to help with this ongoing issue. Knowing what to look for, maintaining tidy outdoor areas, and reporting sightings can offer significant contributions to keeping these ants at bay. When it comes to these invasive ants, a little vigilance can go a long way.