"These bees are huge! They are almost the size of my thumb and hundreds of them are all over my garage! What are they?"
I started getting calls like this a couple of years ago. Reports of giant mutant bees began to pour into the center. One little boy reported a whole nest of queen bees. He knew that queen bees were huge and, since all these bees were huge, they must be queens.
In reality, the bees are European Hornets. They have been in the Northeast since the 1840s, though I did not hear much about them until recent years. They can be up to an inch and a half or so long and are also known as giant hornets. They are unique among insects because they find their food at night, mostly catching caterpillars, crickets, grasshoppers and flies to feed their young.
Photo by Jennifer Schlick
Viburnum leaf Beetle larvae.
Photo by Jeff Tome
This green ash tree is in the Ted Grisez Arboretum at Audubon.
Photo by Jeff Tome
Purple boxes hanging on trees are out to trap Emerald Ash Borers.
European hornets typically nest in hollow trees, but a bird house or garage will work quite well. According to the Penn State Department of Entomology, they are also a more aggressive hornet species. By fall, one nest can contain 800 to 1,000 workers that may sting when the nest is under attack. They don't typically sting unless threatened.
Insects from other countries are appearing in the area almost every year. You may never notice the insects, but you may notice other odd things appearing. For example, you may have noticed odd hanging purple things in some trees. These are Emerald Ash Borer Traps, distributed and monitored by the United States Department of Agriculture (USDA).
The Emerald Ash Borer is a small, metallic-green beetle discovered in Michigan in 2002. This insect is an Asian native and believed to have arrived in this country in wood-packing material.
It first found it in Michigan as well. I was driving to a conference when I saw my first Emerald Ash Borer billboard. It showed a huge photo of the borer and asked people not to move firewood, since that would spread the eggs and larva around the state. That's still the message today. Move firewood and you spread the borer.
Why's it a problem? This insect is responsible for the death of 15 million Ash trees so far. Only Ashes are affected. The larvae kill the tree by chewing through the phloem, the part that carries nutrients to the tree. The borers keep the nutrients from reaching the whole tree and the tree dies in one to three years.
The purple traps contain a sticky glue and oil from the Manuka tree. This family of insects is more attracted to purple colors, so the color helps attract the insect. The smell of Manuka oil attracts the borers and the glue traps them.
No one knows how extensive the Emerald Ash Borer problem is, so the traps will help locate areas where there is an infestation. The boxes do not indicate that the borers are there. They are just testing to see if they are there. Traps are placed across the region in a roughly 1.5-mile grid.
Expect to see the purple traps through the summer while the borers, if present, are in flight. The traps will be removed and checked in the fall. Please do not remove the traps. If you see one on the ground, call the USDA at (866) 322-4512.
Another insect that has invaded the area in the last few years is the Viburnum leaf beetle. Although they have been in North America since 1948, it is only in the last few years that this beetle has entered the area. The larva of this European beetle devour the leaves of viburnum bushes, stripping them bare. If you've seen big stands of bushes with no leaves at this time of year, chances are they are, or were, viburnums.
The viburnums at Audubon started dying a couple of years ago from all the larva munching on them. There are a few patches that still try to leaf out, but these leaves are quickly devoured by the beetles. The insects have now spread from New York into Pennsylvania, Ohio and Vermont.
Insects from other countries have few to no natural predators. There are often far more in a new habitat than in the country they came from, where other animals eat them. We have seen epidemics of various exotic insects over the years, including gypsy moths, Japanese beetles, Asian lady bugs and more.
No one knows when an ecosystem adjusts to the presence of these insects, if they ever do. Ecosystems change slowly, in a time measured in human lifetimes. If you are not paying attention, you may never even notice that things are different.
We have seen many plants and animals introduced into our environment in the last 50 years, but we have only begun to see a glimmer of how nature responds to them. I hope that there will still be Ash trees and Viburnums left for the future.
Jeff Tome is a naturalist at the Audubon Center and Sanctuary, located at 1600 Riverside Road just east of Route 62 between Jamestown and Warren. An Emerald Ash Borer trap can be seen in the Ted Grisez Arboretum at the center and along roadsides everywhere.