The massive defoliation of trees in southern New England by winter moth and gypsy moth caterpillars this spring and summer has totally changed the look of the regional landscape. And while scientists say it is unlikely that many trees will die as a result of one year of defoliation, it raises the question of how it will affect other species of wildlife.
University of Rhode Island ornithologist Peter Paton says that several varieties of songbirds are likely benefiting from the huge number of caterpillars swarming the area. Black-billed and yellow-billed cuckoos, two species that are known to eat large numbers of caterpillars, including the prickly gypsy moth caterpillars that many other birds avoid, are likely to thrive this year. He said that birdwatchers in the region have noticed an unusually large number of very active cuckoos since the birds arrived from their wintering grounds in South America in May. As a result, the birds will probably have a very successful nesting season.
“Last week I was watching some robins 40 feet up in a tree foraging, which is a pretty unusual place to find them eating,” he said. “So I’m guessing they were probably feasting on caterpillars, too.”
Paton also observed blue jays and hairy woodpeckers tearing apart some of the abundant caterpillar cocoons, another unusual behavior brought about by the caterpillar infestation.
“And if the defoliation ends up killing trees,” he added, “that could eventually have a positive impact on woodpeckers,” which consume insects that live in dead trees and which drill nesting cavities in dead trees.
As for other possible effects on wildlife, he speculated that the absence of leaves on many trees will enable sunshine to filter down to the forest floor and other areas that are typically shady, which may provide additional sunny areas for turtles and snakes to nest and sun themselves.
On the other hand, fewer shady areas may make it more difficult for wood frogs and salamanders living in the forest to remain cool and moist, according to David Gregg, executive director of the Rhode Island Natural History Survey.
“Ferns and other forest floor plants are also more likely to have a negative experience of this phenomenon than a positive one,” he added.
Natural History Survey botanist Hope Leeson said there will be both winners and losers on the forest floor, depending on the needs of the species living there. “If there is an understory of trees and shrubs, they’ll be happy to have the sun.”
Leeson points to greenbrier as one plant that will thrive with the additional sunlight penetrating to the forest floor, and it will provide benefits to other species that may be at risk.
“At the moment, any small mammal living in the forest doesn’t have any cover,” she said. “Deer have eaten all the tree seedlings and shrub seedlings, so there isn’t anything for the mice and chipmunks to hide under. Once the canopy was removed by the caterpillars, it made it easy for the hawks and owls to see the small mammals pretty well.”
The increased growth of greenbrier, she said, will provide the small mammals with new places to hide.
Leeson and Gregg also noted that some unwanted invasive species may also thrive this year, thanks to the defoliation. Amur cork trees, for instance, an Asian species, have invaded forests throughout the Mid-Atlantic States and are now found in small numbers in coastal forests of Rhode Island as well. They grow very slowly in the shade, with some 25 year-old trees no more than eight feet tall with trunks only an inch or two in diameter.
“They just wait it out in a shady situation,” Leeson said. “They just eek out an existence and wait for the moment when there’s light, and that’s when they put on a lot of growth.” And this year could be the year they will shoot skyward.
According to Rick Enser, retired biologist for the Rhode Island Department of Environmental Management, if the region experiences another gypsy moth infestation next year, tree mortality will likely increase, which could create gaps in the forest for new species to move into.
“Unfortunately, invasives are highly adept at dispersal, although small infestations within forest openings should theoretically be reduced or eliminated as the canopy returns,” he said.
He points to winged euonymus, also known as burning bush, as one invasive species that can spread quickly to new areas and survive when the forest canopy returns. It is a shrub that has become a primary concern at URI’s W. Alton Jones Campus.
Because it has been more than 30 years since Rhode Island has experienced such a severe defoliation, many of the environmental effects are uncertain and unstudied, leaving some scientists with more questions than answers.
“I was wondering about the nutrient balance,” said Gregg. “Normally oak leaves breakdown in a certain way at a certain time, but this year they've been consumed by caterpillars and turned into manure and sprinkled all over the forest floor. So is that good for the plants? What's the nutrient analysis of gypsy moth poop?”
This article first appeared in EcoRI.org on June 29, 2016.
Friday, July 1, 2016
Wednesday, June 22, 2016
Six reasons to love dragonflies
When the joyful noise of spring
subsides for the summer and most birds remain hidden to raise their broods,
more and more wildlife enthusiasts are turning their attention to another of
nature’s spectacular aerialists – dragonflies. Dressed in brilliant, iridescent
colors and with names like ringed bog haunter, unicorn clubtail and sparkling
jewelwing, dragonflies and their close relatives damselflies are easy to get
hooked on once you start paying attention.
Biologist Ginger Brown, Rhode
Island’s leading dragonfly expert, who some call the dragon lady, says it’s the
“combination of a strikingly handsome insect and their really dynamic behaviors
that attract the general public to dragonflies. They’re the hawks of the insect
world.”
For those who aren’t yet convinced,
here are six reasons why dragonflies are the most fascinating creatures in the
insect world and deserving of your interest.
1. Their flight skills are
unparalleled.
Dragonflies can fly forward and
backward and hover in place. They can stop on a dime, rapidly change
directions, and fly upside down. The military has even studied their flight
skills to improve the design of helicopters.
Those flight skills come in handy as they cruise around local ponds and
swamps hunting for other flying insects that they capture and consume on the
wing. They even catch and eat other dragonflies, though dragonflies are
themselves eaten by birds, frogs and other animals.
2. They have an unusual life
cycle.
Most adult dragons and damsels only
fly around for three or four weeks before dying. But before they do so, the
females lay eggs in a pond or stream, and the larva that hatch from those eggs live
in the water for nearly a year before climbing out of the water and
transforming into the beautiful adult insect. “The adult form of a dragonfly is
the shortest part of its life,” Brown said. “The whole mysterious larval stage
is what most people aren’t aware of, and it takes place entirely under water.”
3. They’re ancient creatures.
Dragonflies have been around virtually
unchanged for hundreds of millions of years and were some of the first winged
insects to evolve. They witnessed the evolution and extinction of the
dinosaurs. Although the wingspan of most dragonflies today is between 2 and 5
inches, some of the earliest dragonfly species were about the size of crows.
4. There are more than 5,000
known species of dragonflies in the world.
Until recently, no one knew how many of those 5,000 species were
found in Rhode Island. So Brown led a six-year census of dragonflies and
damselflies in the state beginning in 1998. Her 55 volunteers visited every
pond, stream and wetland in the region to collect and identify specimens, and
they found 138 different species, including 22 that were not known to live in
Rhode Island prior to the census. Burrillville (110) and South Kingstown (108)
have the most species of any community in the state, while Newport (25) and
Central Falls (26) have the fewest.
5. Their sturdy wings make them
safe to handle.
Dragonflying is becoming an
increasingly popular hobby, in part because the challenge of catching them is
so fun. Unlike butterflies, their wings are sturdy, making them easy to handle
and release without harming them. The key to capturing dragonflies is to use a
long-handled insect net and to swing quickly from behind and immediately twist
the handle, ensuring that the captured insect cannot fly out of the net.
Keeping your catch in the net is easier than getting it in there in the first
place, though. Dragonflies have hundreds of eyes, so they can see you better
than you can see them. And with their remarkable flight skills, you’re likely
to swing and miss more often than you’ll want to admit.
6. Their typical behaviors make
them easy to observe.
Dragonflies often perch out in the
open on exposed vegetation, making it easy to get good long looks at them. They
are also very approachable, and they will often approach you as well, sometimes
even landing on you for great photo opportunities. (Don’t worry about their
reputation for sewing children’s lips together; that’s an old wives tale. Their
mouth parts aren’t strong enough to break through human skin.) Best of all,
when they’re feeding, they typically follow the same hunting route around and
around a pond or up and down an open corridor. Once you identify their route,
you can move in close, and they will fly right by you again and again.
For Brown, the exciting part of
dragonflying is that everything they do in their adult life happens while
they’re flying. “You can see them hunting food, consuming food, pursuing a
female, mating, laying eggs,” she said. “Almost their entire life cycle can be
seen at your local pond. So just go to a pond on a nice summer day and you’ll
see it all.”
Saturday, June 18, 2016
Help rediscover the 'lost ladybug'
One of most exciting aspects of
watching wildlife is that you don’t have to be a biologist or full-time
naturalist to make important discoveries about the natural world. It’s not
unusual for recreational birdwatchers to find and identify rare or out-of-range
species, for instance, and the same is true of those who enjoy wild plants,
butterflies, marine life and all sorts of other creatures. Often all it takes is to pay attention to the
species that cross your path and to know enough to wonder aloud if something
seems out of place. And sometimes it takes even less than that.
Take the rediscovery of the lost
ladybug, for instance. That’s not really
its name, and it’s not really lost, of course; it has simply disappeared from
most of its range. The nine-spotted ladybug was once the most common ladybug
found in the eastern United States. It was highly valued for its ability to
suppress pest insects in agricultural fields. One of several dozen species of
ladybug native to the region – all more appropriately called lady beetles –
it’s the official state insect of New York. But over the last 30 or 40 years,
it disappeared with hardly anyone noticing, as non-native ladybugs arrived and
became dominant.
![]() |
| Nine-spotted ladybug by Larry Jernigan |
Nine-spotted ladybugs look somewhat
like most other common ladybugs – reddish-orange with black spots. But this one
has exactly nine spots, four on each elytra (that’s the reddish part that
covers its wings) and one spot in the middle that’s split by the two elytra.
In 2004, researchers at Cornell University started the Lost Ladybug Project to encourage the general public to
look for it. They asked people to take photographs of any ladybug they find and
post them to a website for experts to identify. By 2014,
citizen scientists had submitted 30,000 ladybug pictures but found very few of
the nine-spotted variety, mostly in scattered locations in the West. Just one
was found east of the Great Plains.
In June of that year, however, a volunteer participating in the
Rhode Island Natural History Survey’s annual biodiversity field day, BioBlitz,
found a nine-spotted ladybug at Rocky Point in Warwick. It was the first record
of the species in the state in at least 30 years, and no one knows exactly who
found it – probably one of a group of kids using insect nets to capture
whatever they could find. It took almost a year for all the insects collected
that day to be identified. When the specimen was finally brought to the
attention of the Cornell team, they rushed to the site to look for more but
found none.
So David Gregg, director of the Natural History Survey, and the
Cornell researchers hope you’ll join the hunt for the lost ladybug. June is the
peak of ladybug season in Rhode Island, so if you see a ladybug that has even the
slightest chance of being a nine-spotted ladybug, post a picture of it to the
Lost Ladybug website. The site has tips for finding and photographing ladybugs,
along with fact sheets so you can learn to identify the other ladybugs in the
area.
The best chance of finding one is probably somewhere around Rocky
Point, since that’s where the last local specimen was found. But the next one
could turn up almost anywhere, including in your backyard. So be on the
lookout.
This article was first published in The Independent on June 16, 2016.
Wednesday, June 15, 2016
Naturalists tally 1,066 species in 24-hours at Hopkinton preserve
More than 200 volunteer naturalists explored every corner of the Kenyon Crossroads Preserve in Hopkinton last weekend during the 17th annual BioBlitz, and in just 24 hours they tallied 1,066 species on the property – everything from birds and mammals to mushrooms, dragonflies and spiders. They even identified two viruses.
“To have gone over 1,000 species on a 100-acre parcel with no coastal or marine component is huge,” said David Gregg, executive director of the Rhode Island Natural History Survey, which organizes the event. “I’m pretty sure that’s the highest total of any BioBlitz site without a marine component.”
Among the species identified were 21 mammals, 79 birds, 12 fish, 12 amphibians, 8 reptiles, 432 plants, 70 lichens, 81 fungi, 30 dragonflies, 49 beetles, 21 butterflies and 117 moths. The most notable discoveries were a very rare species of honeysuckle and two presumably breeding northern parulas, a small songbird known to breed in only a few locations in the state.
The preserve is owned by the Hopkinton Land Trust, which hosted the volunteers, many of whom camped overnight at the site, including a group of middle school students from Central Falls and the Envirothon team from Coventry High School.
“We’ve owned the property for quite some time, but we finally got it looking the way we want it – with the parking lot and the trails in,” said Ed Wood, a member of the land trust who helped organize the event. “So now we’re trying to make it more well known. That’s one of the reasons we wanted BioBlitz here.”
Keith Bowman traveled from Swarthmore, Penn., to participate in the event and lead the team counting mosses and lichens.
“I don’t get to do this on a daily basis, so it’s a chance to interact with people who are interested in the same things I’m interested in, and a chance to share what I know with other people who want to learn about it,” said Bowman, who manages a tutoring office.
He said the 70 species he identified was a good total for a 24-hour event.
“Mosses take a lot of work to identify,” he said. “A lot of them have to be verified under a microscope. When I’m in the field, I’m looking for those with different color, texture, size and from different substrates and environments. The differences are very small scale differences, so when they’re under the microscope, I’m looking at cell size, shape, structures and veins.”
While most of the members of the BioBlitz dragonfly team wandered the preserve with insects nets attempting to capture dragonflies and damselflies, Kirsten Martin contributed to the team’s effort by using a microscope to identify dragonfly larvae scooped from the muck of a nearby pond.
“I’m addicted to Bioblitz,” said Martin, a professor at the University of St. Joseph in West Hartford. “It’s a lot of fun. And I enjoy hanging out with like-minded people, especially since I’m one of the only environmental scientists at my university. So this is a chance for me to play. You get to start seeing the same people year after year, and I add some knowledge about conservation.”
Her unique expertise added 11 species to the dragonfly list that would not otherwise have been included. “And they all came from just one scoop,” she said proudly.
Lou Perrotti, director of conservation programs at Roger Williams Park Zoo, led the reptile and amphibian team, which spent most of its time looking for snakes by walking the edges of fields, turning over rocks and logs, and investigating stone walls and brush piles.
“We got the likely suspects, but I would have expected more snakes here, given the remoteness of the area and the fact that we’re within range of a lot of species that only occur in a limited area,” he said. “Box turtle and black rat snake should have been here, but we didn’t find them.”
Perrotti said the zoo sponsors BioBlitz almost every year as part of its mission of conservation and education.
“BioBlitz is a great way to inspire the next generation, to bring folks with expertise together to pass information along, and to collect a snapshot of data about the biodiversity of the state. That’s what we’re all about.”
Last year’s BioBlitz was held at the Dundery Brook and Goosewing Beach Preserves in Little Compton, where 1,204 species were identified.
“To have gone over 1,000 species on a 100-acre parcel with no coastal or marine component is huge,” said David Gregg, executive director of the Rhode Island Natural History Survey, which organizes the event. “I’m pretty sure that’s the highest total of any BioBlitz site without a marine component.”
Among the species identified were 21 mammals, 79 birds, 12 fish, 12 amphibians, 8 reptiles, 432 plants, 70 lichens, 81 fungi, 30 dragonflies, 49 beetles, 21 butterflies and 117 moths. The most notable discoveries were a very rare species of honeysuckle and two presumably breeding northern parulas, a small songbird known to breed in only a few locations in the state.
The preserve is owned by the Hopkinton Land Trust, which hosted the volunteers, many of whom camped overnight at the site, including a group of middle school students from Central Falls and the Envirothon team from Coventry High School.
“We’ve owned the property for quite some time, but we finally got it looking the way we want it – with the parking lot and the trails in,” said Ed Wood, a member of the land trust who helped organize the event. “So now we’re trying to make it more well known. That’s one of the reasons we wanted BioBlitz here.”
Keith Bowman traveled from Swarthmore, Penn., to participate in the event and lead the team counting mosses and lichens.
“I don’t get to do this on a daily basis, so it’s a chance to interact with people who are interested in the same things I’m interested in, and a chance to share what I know with other people who want to learn about it,” said Bowman, who manages a tutoring office.
He said the 70 species he identified was a good total for a 24-hour event.
“Mosses take a lot of work to identify,” he said. “A lot of them have to be verified under a microscope. When I’m in the field, I’m looking for those with different color, texture, size and from different substrates and environments. The differences are very small scale differences, so when they’re under the microscope, I’m looking at cell size, shape, structures and veins.”
While most of the members of the BioBlitz dragonfly team wandered the preserve with insects nets attempting to capture dragonflies and damselflies, Kirsten Martin contributed to the team’s effort by using a microscope to identify dragonfly larvae scooped from the muck of a nearby pond.
“I’m addicted to Bioblitz,” said Martin, a professor at the University of St. Joseph in West Hartford. “It’s a lot of fun. And I enjoy hanging out with like-minded people, especially since I’m one of the only environmental scientists at my university. So this is a chance for me to play. You get to start seeing the same people year after year, and I add some knowledge about conservation.”
Her unique expertise added 11 species to the dragonfly list that would not otherwise have been included. “And they all came from just one scoop,” she said proudly.
Lou Perrotti, director of conservation programs at Roger Williams Park Zoo, led the reptile and amphibian team, which spent most of its time looking for snakes by walking the edges of fields, turning over rocks and logs, and investigating stone walls and brush piles.
“We got the likely suspects, but I would have expected more snakes here, given the remoteness of the area and the fact that we’re within range of a lot of species that only occur in a limited area,” he said. “Box turtle and black rat snake should have been here, but we didn’t find them.”
Perrotti said the zoo sponsors BioBlitz almost every year as part of its mission of conservation and education.
“BioBlitz is a great way to inspire the next generation, to bring folks with expertise together to pass information along, and to collect a snapshot of data about the biodiversity of the state. That’s what we’re all about.”
Last year’s BioBlitz was held at the Dundery Brook and Goosewing Beach Preserves in Little Compton, where 1,204 species were identified.
Thursday, June 2, 2016
Road mortality an increasing problem for local turtles
It’s turtle nesting season in
southern New England, which unfortunately means that many female turtles are likely
to get crushed on roadways in the next few weeks as they trek to their preferred
nesting location. It’s an issue that Lou Perrotti, director of conservation
programs at Roger Williams Park Zoo, said is a growing problem caused primarily
by increased development and habitat loss, which forces turtles to cross
streets to reach their nesting habitat.
“This is one of the major threats
that face turtles and tortoise populations every year,” said Perrotti, who has
seen dead turtles of several species on Rhode Island roads in the last two
weeks. “A population can only take a hit of so many adult females before you
lose the entire next generation.”
Rhode Island is home to seven
species of native turtles (excluding sea turtles) – painted, spotted, snapping,
musk, wood, box and diamondback terrapin – and most of them lay their eggs in
late May and early June. Painted and
snapping turtles are the state’s most common species, and they generally only
travel about 100 yards to their nest sites. But that 100 yards can be perilous
because of the road crossings it often requires. Perrotti said the turtles typically seek out
the same egg laying location each year – usually a site with well-drained soil
on a southern exposure that’s close to their pond – so those that cross roads
to get there must do so year after year.
Unlike the movement of frogs and
salamanders to their breeding ponds in March and early April, which occurs
almost exclusively on rainy evenings, turtle migration to their nesting grounds
can happen any time and in any weather, though Perrotti said that you’re likely
to see more turtles during wet weather when wet soils make it easier for them
to dig their nests in. So drivers should keep an eye out for turtles every time
they climb into their vehicles in the coming weeks, especially when driving
near wetlands.
In 2015, University of Rhode Island
student Elizabeth Shadle conducted a study of turtle mortality on roadways in Colonial National Historical Park in Virginia, where many of Rhode Island’s
turtle species are also found. She discovered, rather unsurprisingly, that most
turtles were killed on roads that were adjacent to wetlands compared to roads
near upland habitat.
"It may sound obvious, but it's important to collect the data," Shadle said. "It means that proximity to wetlands is an important predictor of roadkill mortality for aquatic turtle species. and it has implications for species-specific wildlife management."
"It may sound obvious, but it's important to collect the data," Shadle said. "It means that proximity to wetlands is an important predictor of roadkill mortality for aquatic turtle species. and it has implications for species-specific wildlife management."
But just because most roadkilled turtles are struck on roads
through wetlands doesn’t mean drivers shouldn’t also be on the lookout for
turtles when driving through upland areas this season. One of the region’s
rarest turtle species, the box turtle, prefers woodlands, pastures and thickets
over wetlands and is often killed by vehicles.
“Box turtles get whacked way more often than I would have
thought,” Perrotti said. “They look like a big rock in the road, so you’d think
drivers would swerve around them. How do you run over a box turtle unless
you’re just not paying attention?”
So what should you do if you
encounter a turtle attempting to cross the road? Usually, Perrotti said, the best
thing to do is to leave it alone. Picking it up and returning it to a nearby
pond won’t solve the problem if the animal has yet to lay her eggs. She’ll just
turn around and head back across the road.
If a turtle is at risk of being
struck by a vehicle, Perrotti suggests moving it to the side of the road in the
direction it was heading. Just be extremely careful if the species involved is
a snapping turtle, since they have powerful jaws and can inflict serious harm.
And according to a fact sheet from the Rhode Island Department of Environmental Management, it is never advisable
to remove a turtle from the road (or anywhere else) and take it to a completely
new location, since individual turtles have a very specific home range that
they occupy their entire lives.
“You may think you are bringing the turtle to paradise when you
take it to your favorite brook or pond, but in reality you could be giving it a
death sentence,” reads the fact sheet. “Not only is it possible that the turtle
may not find suitable food and habitat in the new home, but many turtles will
try to get back to the area they were moved from. In such instances, they may
travel until they are exhausted or exposed to numerous additional threats, or
they may cross several roads and get crushed anyway.”
This article first appeared in EcoRI.org on June 2, 2016.
Thursday, May 26, 2016
Winning at horseshoes not about getting ringer
Anyone who has spent much time along
the Rhode Island coast is familiar with one of the most ancient creatures on
Earth, the horseshoe crab. More closely related to spiders and scorpions than
to crabs, they evolved more than 300 million years ago, long before the
dinosaurs, and they have remained mostly unchanged ever since. With 10 eyes,
blue blood, and six pairs of appendages, they can look somewhat frightening. Just
don’t believe claims that their tail – called a telson – is poisonous or can
sting. Not true.
What is true about these remarkable
creatures is that horseshoe crabs are far less common at their spawning grounds
than they used to be. The days of seeing hundreds or thousands of horseshoe
crabs scurrying about in local coves are mostly over. And their decline has
implications for a whole host of other marine life. Some sea turtles, for
instance, feed on horseshoe crabs, and many shorebirds, including the very rare
red knot, consume horseshoe crab eggs to fuel their migration northward. Humans,
too, depend on these surprising animals, because their unusual copper-based
blood has properties that are used by the biomedical industry to ensure that
our medical devices, vaccines and intravenous solutions are free of harmful
bacteria.
The cause of their decline is
somewhat uncertain, though large numbers are harvested for use as bait in the
eel and conch fisheries. They also get stranded on beaches and accidentally
flipped upside down by waves, which gives gulls and other predators easy access
to their sensitive parts. And some die during the process of draining a portion
of their blood for biomedical testing.
In Rhode Island, assessments of
horseshoe crab populations by state and federal agencies have found them at “low
levels of abundance” ever since a management plan was put in place in 1999. Scott
Olszewski, a marine fisheries biologist at the Rhode Island Department of Environmental
Management, who conducts spawning surveys at several area beaches, said that
despite efforts to manage the population, their numbers have not rebounded.
About 30 to 40 fishermen obtain permits each year to harvest horseshoe crabs in
the state, and they are allowed to take up to 14,500 for use as bait and
another 34,000 for the biomedical industry (though those in the latter category
are released back where they were captured after some of their blood has been
collected).
“When horseshoe crabs decide it’s
time to spawn, they come up on the beach in massive numbers, which makes
harvesting them pretty easy,” said Olszewski. That’s why the fishing season
often closes just a few days or weeks after spawning begins.
Other scientists are now paying
close attention to horseshoe crabs as well. Researchers at Sacred Heart University are overseeing teams of volunteers who are monitoring them at multiple
locations in Long Island Sound, including at Napatree Point in Westerly. And
others are doing the same on Cape Cod and in the Mid-Atlantic States.
At Napatree, volunteers led by the
Watch Hill Conservancy go out at high tide on full moon nights from May through
July to count and tag the animals. It’s an enjoyable few hours working by
moonlight to the sound of the lapping waves, and it helps provide insight into
the natural history of an ecological oddity that will likely outlive us all.
To learn more about becoming a
horseshoe crab volunteer at Napatree, contact the Watch Hill Conservancy at napatreenaturalist@gmail.com. And if you see large numbers of spawning
horseshoe crabs at other coastal locations, report them to Olszewski at scott.olszewski@dem.ri.gov.
This article first appeared in The Independent on May 19, 2016.
Tuesday, May 3, 2016
Winter moth caterpillars prepare to defoliate the region. Again.
Those annoying white moths that seemed
to be everywhere between Thanksgiving and Christmas, and which sometimes formed
thick fluttering clouds, are preparing to unleash even greater devastation to
the trees in southern New England than they did last year. Winter moth
caterpillars defoliated about 27,000 acres of trees in Rhode Island last spring,
according to data from the Rhode Island Department of Environmental Management,
and one local expert says the insects will do even greater damage this year.
Heather Faubert, who runs the PlantProtection Clinic at the University of Rhode Island and has been monitoring the
approaching onslaught, was hoping that the late cold spell in early April was
going to kill off many of the emerging caterpillars. But that doesn’t appear to
have happened.
![]() |
| Winter moth caterpillar photo by Milan Zubric |
“I think we’re in trouble this
spring,” she said. “Every year since they arrived, it’s been getting worse, and
I can’t imagine why it won’t get worse this year, too.”
Winter moths are a European insect
that arrived in North America in the 1950s, beginning in Nova Scotia. They
spread to Cape Cod by the 1990s and were first discovered in Rhode Island in
2004.
“They expand slowly, so there are
still some places in Rhode Island where they aren’t found in large numbers
yet,” Faubert said. “But they’re coming. The first year they arrive in a new
area, you might see the moths in winter but not see many caterpillars the next spring.
But once they get going, they grow exponentially.”
The URI entomologist said the adult moths appear in late November
and fly around through December looking for a mate. Killing them at that time
does little good, since only the males fly. Unseen flightless females lay their
eggs on the trunks and branches of trees, and the caterpillars emerge in late
March.
“Hatching typically takes about
eight days to complete, but because of the cold weather in April it took about
a month this year,” Faubert said.
The tiny caterpillars then crawl
into the buds of the earliest budding trees – mostly maples, but also apple and
other fruit trees – and immediately start eating. If the buds of fruit trees
are consumed, the fruit crop may be lost for the year. As leaves emerge on
trees of all varieties, the caterpillars feed on them until the end of May,
when they drop to the ground, burrow into the soil, and pupate before emerging
as adult moths in November.
While one year of defoliation
doesn’t typically harm a healthy tree, Faubert said that defoliation three
years in a row can kill almost any tree. And this year, Rhode Islanders may have
a large population of gypsy moths to contend with as well.
“Trees that are defoliated by winter
moth and then again by gypsy moth later in the season probably won’t recover,”
Faubert said.
Gypsy moths defoliated about 43,000
acres of Rhode Island forest last year, thanks to a dry May that aided their
survival. In years when it’s rainy in May, the moisture abets several diseases
that get passed back and forth between gypsy moth caterpillars, causing the
population to crash. So Faubert has her fingers crossed that Rhode Island will
experience a wet May.
Homeowners seeking to protect their
trees from winter moth defoliation should take action immediately. Faubert said
that it’s best to spray insecticide on trees while the winter moth caterpillars
are still small. “Waiting until the trees are halfway defoliated won’t really
do much good,” she said.
According to a DEM factsheet, the recommended
treatment against the caterpillars is a pesticide containing the relatively
safe bacterium Bacillus thuringiensis
or Bt. Caterpillars die when they consume leaves sprayed with the pesticide,
which is most effective before the caterpillars are full grown.
“That’s the safest thing to do,”
Faubert said. “The problem is that the spray only lasts from 3 to 5 days before
it breaks down. So if you have a prized tree you’re trying to save and there
are untreated trees nearby, caterpillars may get blown onto your tree after the
pesticide is no longer effective. So one shot of insecticide may not do the
job.”
Physical barriers like sticky tape
or grease applied to the base of trees is not considered effective at stopping
winter moths.
One strategy that Faubert has
experimented with is biological control. Researchers have identified a
parasitic fly that is known to control the spread of winter moths in their
native Europe. The fly lays its tiny eggs on tree leaves, and when the
caterpillar consumes the eggs while eating the leaves, the eggs hatch inside
the caterpillar and eat the caterpillar from the inside out.
Faubert released groups of the parasitic
flies in seven locations in Rhode Island between 2011 and 2014. But, she said,
“if it’s going to work, it takes years.”
In the meantime, she advises
residents concerned about their trees to contact a local landscaper or arborist
who can assess and treat their trees. The website of the Rhode Island Nursery and Landscape Association has a list of those who can do
the job.
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