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The Invaders

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ALBANY — Earthworms, starlings and honeybees. Oh my.

Perhaps they’re not as threatening as lions, tigers and bears, but at the New York State Museum they’re three of the more than 50 invasive, nonnative species — bugs and plants included — that make up a new exhibit called “The Invaders.” In many ways they make things a bit tougher for the natives, but that doesn’t mean Cliff Siegfried and his staff at the New York State Museum are out to get all of them.

“We just want people to realize that when new species are introduced into an area, they’re not coming into a vacuum,” said Siegfried, an environmental biologist at the museum since 1979 and its executive director since 1999. “There are no vacant niches out there waiting for an exotic invader, and you can never be sure what kind of impact a new species will have. Often, it’s a negative one.”

Some are bad news

While earthworms, starlings and honeybees are among the invasive, nonnative species that were introduced into North America a long time ago, there are a group of more recent and more harmful visitors scientists are quite concerned about, such as purple loosestrife, mitten crabs and snakeheads. The snakehead is in particular an ominous invader, a fish that is a voracious top-level predator with no natural enemies. Accidently introduced into the ecosystem in Maryland a few years ago, the snakehead can decimate populations of native fish.

“The snakehead is certainly a dramatic example of what we’re concerned about,” said Siegfried. “But purple loosestrife and mitten crabs also have negative impacts. The purple loosestrife grow in such dense stands that they eliminate other species in wetlands and other marshy areas. We’re not sure yet what the repercussions are, but when you have an ecosystem with 30 or 40 species and that biodiversity gets decreased, we’re not sure what’s going to happen. What you want is a stable and diverse ecosystem and when you eliminate species everything becomes destabilized.”

Purple loosestrife is a wetland plant from Europe and Asia that was introduced to America during the 19th century. It is an erect perennial herb in the loosestrife family, with a square, woody stem and opposite or whorled leaves. Loosestrife plants grow from 4 to 10 feet high, depending upon conditions, and produce a showy display of magenta-colored flower spikes throughout much of the summer. It easily adapts to natural wetlands and as it establishes and expands, it out-competes and replaces native grasses, sedges and other flowering plants that provide a higher quality source of nutrition for wildlife. Its highly invasive nature also poses a threat to waterfowl by reducing their habitat.

“They are beautiful, it’s a nice splash of color, and I’ve even put a few in damp spots in my backyard,” said Siegfried. “But the issue is the integrity of the ecosystem. A lot of what you can buy now at a nursery is not native to this state. So we’d like people, when they’re planning on putting in a garden, to look for the native species. If you put in native plants, you know you’re not going to do anything that might change the structure of the ecosystem.”

Everything’s connected

Included in the exhibit is a segment on zebra mussels, which were brought into the state’s waterways through ship ballast water and have caused millions of dollars of damage. Also on the enemies’ list are a variety of beetles that like to eat wood for breakfast, lunch and dinner.

“There are some serious cases where the invaders are real pests,” said Siegfried. “Any boring beetles of that nature can devastate an industry, and in nature everything is connected one way or another. If something gets eliminated, we don’t know what all the ramifications will be down the road.”

As for the fate of the nine-spotted ladybug, New York’s state insect, the outlook looks rather bleak.

“It’s about gone, and it very well might be gone,” said Siegfried. “If there’s one that still exists in the state it’s very rare. If somebody sees one, we’d like to know.”

Up through the 1940s, the nine-spotted ladybug was the most common ladybug in New York state until its population suddenly plummeted. It hasn’t been collected in the state since the 1970s, and this was likely caused by the introduction of the closely related seven-spotted or Asian ladybug, now quite abundant.

“We introduced the Asian ladybug because it was considered beneficial and it was in many ways, but it competed so well it had a very negative impact on the nine-spotted ladybug,” said Siegfried. “Now that species could be extirpated, and that’s sad.”

Shakespearean tragedy

One species Siegfried wouldn’t mind

seeing less of is the starling, introduced

into this country in the early 19th century by fans of Shakespeare.

“The starlings were introduced into New York’s Central Park because somebody thought that every bird that was ever mentioned in Shakespeare should be here in New York,” said Siegfried. “Now there are billions of them here, and I think it’s safe to say they are pests.”

Earthworms, eliminated from North America by the Ice Age, were reintroduced into the U.S. during the influx of European settlers in the 17th century. While that species appears safe, the future is uncertain for honeybees, which were also brought over in ships by immigrants from Europe in the 18th century. Only recently, scientists have noticed a decrease in the number of honeybee hives.

What will become of honeybee?

“The honeybee was an invasive, nonnative species but no one would suggest we get rid of it now,” said Siegfried. “The problem is, however, there’s been a hive collapse and we don’t know yet what’s causing it or what we can do about it. If the honeybee is eliminated, agriculture as we know it is going to change. If that happens, hopefully we’ll have in our native bee population something that might be able to replace it.”

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