Invaders of Connecticut

At this very moment Connecticut is fighting back an invasion! These invaders hurt the Connecticut economy, cause environmental devastation, and sometimes even do harm to humans. Some invaders make themselves obvious but we might be fond of others before we realize their true nefarious nature. These invaders are plants and animals whose species don’t belong here, and they’re called invasive species.


The invasive mile-a-minute vine can grow 6 inches in one day!

The invasive mile-a-minute vine can grow 6 inches in one day!

What is an invasive species?

Invasive species are non-native organisms that have found their way into a new environment. Sometimes invasive species arrive accidentally, like if someone unknowingly takes a fungus to another country after boarding a plane with spores on their shoes. Other invasive species are established on purpose. Rabbits were originally released into Australia to provide food and hunting for British colonists. Now they have multiplied and become an ecologic disaster.  

Not all foreign species will survive in a new environment. The most successful invasive species are adaptable and able to tolerate a wide variety of conditions. A lack of natural controls in a new environment will make it even easier for an invasive species to spread. A species that recently arrived in a new land might not have any predators to keep populations in check.

Invasive species become a problem when they outcompete or otherwise threaten native species. They might take resources, prey upon native species, or maybe just physically occupy the spaces where native species once lived.


Connecticut’s Most (Un)Wanted

Connecticut has a lot of invasive species that are causing problems. The Connecticut Invasive Plants Council has come up with a list of almost 100 invasive plant species that have found their way into the area. When you consider invasive animals as well the situation looks even more dire. Some of these species can be fought back with fierce environmental protection measures. For many others, the path forward is not so clear.

  • Emerald Ash Borer

The emerald ash borer is actually a rather pretty insect, a member of a family called the jewel beetles. Unfortunately, the damage caused by emerald ash borers is anything but pretty! The emerald ash borer was introduced into North America somewhere near Michigan in the 1990s. Since then it has spread south down the east coast and west as far as Colorado.

Like its name suggests, the emerald ash borer is very destructive to ash trees. It has killed tens of millions of ash trees already and poses a great danger to the remaining 8.7 billion in North America. The emerald ash borer came to Connecticut in 2012. Environmental protection agencies are doing what they can to suppress its spread but so far the emerald ash borer is here to stay.

  • Asian Shore Crab

Courtesy of GFDL

Courtesy of GFDL

The first Asian shore crabs to reach the waters off New England probably hitched a ride on ships bringing trade goods from the coastlines of China or Japan. They were first noticed in New Jersey in 1988. Now they are abundant from Maine to North Carolina. Asian shore crabs can survive wide ranges of salinity and temperature. They have a rather broad diet which includes the food sources of native crabs, fish, and shellfish.

Mud crabs are being displaced by Asian shore crabs taking over their habitats. Other native species are being eaten by these hungry crustaceans. Where Asian shore crabs emerge native crustaceans go into decline. Even larger species like blue crabs and lobsters are forced into competition for food when the Asian shore crab comes to town.

  • European Starling

Courtesy of Dick Daniels

Courtesy of Dick Daniels

The aerial acrobatics of starling flocks are a beautiful autumn sight in Connecticut. Thousands of starlings move as one in mesmerizing murmurations. The only problem with the display is that starlings are not native to North America. We would ecologically and economically be better off without them.

Starlings were an intentional introduction into the local biosphere. About 60 starlings were released in Central Park in 1890 by an overzealous Shakespeare fan who wanted the Bard’s birds to fly American skies. A population of millions came from those first few. Those millions devour crop pests but they also devour the crops. They transmit diseases to people and livestock, especially where they congregate to eat livestock food. Their droppings foul our streets and cars as well as providing medium for the growth of harmful fungi. Sometimes they even badger native bird species out of nesting sites.

Starlings have been here in Connecticut for over a hundred years. At this point, it is unlikely that we’ll ever be rid of them.

  • Purple Loosestrife

Courtesy of Liz West

Courtesy of Liz West

Purple loosestrife is another beautiful species hiding a dark secret of invasion. Purple loosestrife has spread all over the US and causes great harm to delicate wetland ecosystems. When purple loosestrife finds itself in a new area it multiplies rapidly, crowding out native plants like cattails and sedges. Wildlife that depends on native plants for food, shelter, or nesting sites likewise suffers.

Connecticut environmentalists are fighting purple loosestrife with a campaign of biologic warfare. Galerucella leaf-eating beetles are the soldiers. These beetles love to eat purple loosestrife and they have been released where purple loosestrife is common. The hungry little helpers are so good at reducing purple loosestrife that there is hope yet for beating back this invasion! However, we still have a long way to go. 

  • Zebra Mussel

The good news is that the zebra mussel invasion of Connecticut is still in early stages. They have been found in several freshwater lakes but have not yet reached the levels of infestation seen in more affected areas. The bad news is that the zebra mussels could cause severe damage if they are able to settle in. They can coat boats, anchors, and docks with their sharp-edged shells. They sometimes block pipelines and prevent water intake. They spread avian botulism, which has killed thousands of birds in the Great Lakes area. Boaters and fishers should take care not to transport water or aquatic vegetation to new areas to help prevent zebra mussel spread.

  • Porcelain Berry

Courtesy of Qwert1234

Courtesy of Qwert1234

Porcelain berry was originally cultivated as a landscape plant. Even now it is still used ornamentally despite evidence that it will spread aggressively if left unchecked. The colored berries are a food source for birds which spread its seeds through their droppings. Where porcelain berry takes root it climbs over preexisting vegetation, depriving it of light and ultimately killing it. It is voracious in its consumption of sunlight and habitat.


There are many more invaders threatening Connecticut. Garlic mustard, mile-a-minute vine, and Asian longhorned beetles are just a small sample of the many foes we have to face. There is even a species of parakeet that has made Connecticut its new home, much to the irritation of those affected by the power outages they cause. Invasive species are an enormous problem but there are still things that individuals can do to help prevent their spread:

  1.  If you own a boat, clean your boat thoroughly before moving it to a different body of water.
  2.  Don’t release exotic animals or pets into the wild. This includes aquarium fish!
  3. Clean off your boots and clothes between hikes so you don’t carry seeds from one place to another.
  4. Plant native plants rather than exotics in your yard and garden.
  5. Be careful about carrying agricultural products like fruits and vegetables from place to place. Even firewood can transport pests!
  6.  Volunteer your time to help remove invasive species from local parks.

- Kate Dzikiewicz, Paul Griswold Howes Fellow