The avian breeding season is winding down. Even a few southbound shorebirds will trickle through the region this month on their “fall” migration. But as the dawn bird chorus now fades from northern woodlands, fields and wetlands erupt in the sparkle and drama of summer insects. Here’s a short guide to some of July’s natural history.
By Spencer Hardy
Everyone knows the deer fly–but do you REALLY know the deer fly? With approximately 29 species in the genus Chrysops in Vermont there is a lot to know. Larvae can live up to three years as decomposers and predators in water, while as adults their eyes are among the most psychedelic things in the natural world. A few species even have color patterns that rival any butterfly. Males (which are rarely encountered) don’t bite and are potential pollinators since they visit flowers for nectar.
In many ways they are the perfect group for nature enthusiasts–ubiquitous, diverse, easy to ‘collect’, and relatively easy to ID–yet for some reason they don’t get the attention they deserve. July is an ideal time for deer fly appreciation, as diversity seems to peak early in the month with overall abundance climbing through the end of the month. Boggy, forested areas are great places to find uncommon species, but every site seems to have a unique suite of species, with as many as 10 different species in a single area.
So next time you swat one off the dog or pull one from your hair, take a second to appreciate it, and then photograph it for the Vermont Atlas of Life on iNaturalist. A clear shot of the wings and abdomen is enough to ID many species, though side and face shots are also helpful. A straightforward and well-illustrated key can be found here. There are also plenty of other Tabanidae that you may encounter as well, including some frighteningly large ones and a genus (Stonemyia) that only visits flowers and doesn’t suck blood. Just perhaps, come September, this year you will find yourself missing deer flies!
By Kent McFarland
There are over 8.7 billion ash trees growing in the lower 48 states, comprising 16 species, and they’re all susceptible to loss from the introduced Emerald Ash Borer. But there’s more at stake than just the trees. A recent survey has revealed that 100 species of ash-dependent specialist invertebrate herbivores are too.
Emerald ash borer (EAB; Agrilus planipennis) is an exotic beetle that was discovered in southeast Michigan in 2002. The adult beetles nibble on ash foliage but cause little damage. The larvae feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients, eventually killing it. Healthy ash trees can die within 1-4 years of showing their first sign of infection. EAB probably arrived in the United States in wood packing material from its native range in Asia. As of May, it is now found in 33 states and 3 Canadian provinces.
Adult Beetles are metallic green and about 1/2-inch long and leave a D-shaped exit hole in the bark when they emerge in spring. Woodpeckers like EAB larvae; heavy woodpecker damage on ash trees may be a sign of infestation.
A study by David Wagner at University of Connecticut and Katherine Todd from Ohio State found that 100 species in 5 insect orders and several mites would be imperiled or extirpated by the loss of ash trees. Thirty-nine of them belonged to just four groups: sphingid moths, plant bugs, bark beetles, and seed weevils. A third of the total species were moths (33 species), including 9 species of hawk moths (4 are known from Vermont and 6 are known from the Northeast), about 8.5% of resident North American hawkmoth species. Hawk moths are important pollinators and food for birds and mammals.
The biologists lamented that we were missing even basic information about host breadth, distributions, and life histories for even seemingly well-known species and argued that targeted surveys of all 16 species of ash trees were needed. Meanwhile, you can report all of your ash tree observations and the insects on them to the Vermont Atlas of Life on iNaturalist, and keep your eye out for signs of Emerald Ash Borer.
iNaturalist Vermont Observations
By Emily Anderson
When the summer’s heat roles in, who wouldn’t like an island getaway? For Lake Champlain’s Common Tern populations, islands aren’t so much a vacation home as they are a nursery. Each year, several islands in northern Lake Champlain serve as nesting grounds for these sleek birds. Common Terns winter in Central and South America, returning to Vermont in the late spring to breed and raise their young. Once the eggs are laid, it takes about 3 weeks of incubation for the chicks to hatch. Although they are mobile enough to seek shelter from predators after a day or two, it takes about 21 days for them to fly. In the meantime, the adults bring them fish caught by skimming the water’s surface. In late August, Common Terns begin their long journey south for the winter. If you miss seeing one of these stunning birds while they’re in the northeast, don’t worry—many will be back next year. Approximately 80% of Lake Champlain’s Common Terns return annually to nest.
While it may be tempting to seek out a close-up of their mossy-looking chicks, please keep your distance from the islands. Human disturbance, along with owl predation and over-crowding by Ring-billed Gulls are the likely cause of dramatic declines that occurred in Lake Champlain’s tern populations in the late 1980s. In the 1960’s, Common Terns were one of the most prevalent tern species in the Lake Champlain basin with 300-400 breeding pairs documented. However, by 1988, their numbers had plummeted to around 50 breeding pairs.
Thanks to conservation efforts implemented by Audubon Vermont, Vermont Fish & Wildlife, Lake Champlain Land Trust, and other partners, Lake Champlain’s Common Tern populations have recovered some. Over the past 30 years, populations have slowly rebounded, with most recent records documenting around 275 pairs. Besides conserving the islands where they nest, other successful measures include posting islands to minimize human disturbance, building “chick shelters”, and controlling gull populations. While this marks an encouraging recovery from their low point, they still have some more ground to cover before they can be removed from Vermont’s endangered species list.
If you want to learn more about the Common Tern Recovery Project, check out this article from Audubon Vermont or listen to this episode of Outdoor Radio. And make sure to report your Common Tern sightings on Vermont eBird!
By Kent McFarland
Four plants serve as a backdrop for four natural history events not to be missed here in the Northeast each July. So consider this your annual reminder to seek out drama among the plants.
The Milkweed Trap
Although it is by no means a carnivorous plant, Common Milkweed can be a killing field for small insects. Take the saga of this Virginia Ctenucha moth. With two legs stuck in milkweed flowers like a Chinese finger trap, the moth was struggling to free itself. On another flower nearby only a leg remained from an insect’s previous struggle. Survey enough milkweed flowers and eventually you’ll find a few dead insects, usually small species, left dangling from a leg or two. What’s going on here? Here’s a full report from a field full of milkweed.
Photo 1: from https://www.inaturalist.org/observations/775407
The Primrose Ruse
Like most of you, Bryan Pfeiffer likes to spend his summer leisure time contemplating the tongue of the Primrose Moth. Okay, it’s not exactly a tongue. Butterflies and moths have a straw-like proboscis that they coil like a watch spring and unfurl to suck nectar from flowers (and essential minerals from mud or scat). The Primrose Moth’s proboscis is about half the length of its body. That anatomy alone might be enough to generate interest in this insect. But now consider that the Primrose Moth is Pepto-Bismol pink with a lemony margin at the tips of its wings. In that pink presentation and probing proboscis, the Primrose Moth offers us a lesson in form, function, and evolution. Read more on Bryan’s blog.
A Tiny Floating World
At the height of summer many ponds are covered in lily pads with beautiful white or yellow flowers spread across the surface. Moose munch on them. Beaver and muskrat devour them. Deer consider them delicious. But peer a little closer and you’ll find an amazing miniature world inhabiting each floating leaf. Even moths find a home on water lilies. The caterpillars of the Waterlily Borer Moth (Elophila gyralis) feed on leaves and tunnel into the stalks of the lily pads. Here’s a report knee deep in a pond.
Photo 1: from https://www.inaturalist.org/observations/367417
A Ruby-throated Hummingbird can extend and retract its tongue about 13 times a second. Jewelweed, with its bright orange flowers, attracts hummingbirds and takes advantage of their particularly speedy eating habits to dust the bird with pollen. A single hummingbird can visit as many as 200 flowers in 15 minutes, but can only collect a small amount of nectar – the equivalent of about a few grains of sugar – from each flower.
Ethan Temeles and his students at Amherst College discovered that the jewelweed flower is specially adapted for the feeding style of the hummingbird. The only thing you might notice while watching one of Ethan’s videos of a hummingbird feeding at a jewelweed flower is that the flower shakes back and forth while the bird’s bill probes into the flower. This doesn’t seem like anything remarkable, but to the biologists it was a clue.
Apparently, the flower movement is an adaptation to better smear pollen on the unsuspecting hummingbird. The jewelweed flower has a tiny opening that is about four millimeters wide at the entrance and quickly narrows to only one millimeter wide, bending sharply down and back again toward the front of the flower. At the end of this circuitous tube is the liquid prize for the hummingbird: sweet nectar.
The bird hovers in front of each blossom, using its long tongue to reach down into the flower tube. When the tongue gets to the sharp turn in the tube, it pushes the flower away, then continues on to the end of the tube, where nectar flows into channels on the tongue. The bird then pulls its tongue back to drink the nectar, thus releasing pressure on the back of the tube.
Each jewelweed flower hangs from a stem with just enough tension to allow it to spring back and forth as the hummingbird feeds, depositing pollen on top of the bird’s bill and forehead. When the hummingbird visits another flower, the pollen it carries is brushed off, thus fertilizing a new flower.
Photo 1: from https://www.inaturalist.org/observations/165338
By Kent McFarland
Monarchs are famous for their amazing fall migration, flying thousands of miles from the northern U.S. and Canada south to winter in the mountains in central Mexico each year. The last generation of monarchs, those that will ultimately migrate, are produced in July – perhaps in a milkweed patch near you.
Arriving as early as mid-May in some years in the Northeast, monarchs probably have two generations here during the summer before migrating southward each fall. Some years, its impossible to find caterpillars of the second generation in July and August, while in other years (last year was above average), they seem to be plentiful. I have noticed that in late July and August, the place to find hungry caterpillars is on younger and more succulent milkweed. And in late summer, the only places you find this are areas that were mowed in early July.
Research in New York found that manipulating Common Milkweed phenology through mowing could be used to increase monarch productivity in late July and August. Biologists mowed strips in fields at the beginning of July, late July, and mid-August. They compared these to unmowed control areas by carefully monitoring milkweed growth and counting monarch eggs and caterpillars. As they predicted, mowing fields with Common Milkweed extended the monarchs’ breeding season and increased overall monarch reproduction.
The authors wrote, “We found mowing on July 1 and 24 spurred the regrowth of milkweed and sustained a more continuously suitable habitat for monarch oviposition and larval development than the control. Mowing on August 17 proved too late for recovery of the milkweeds. Significantly more eggs were laid on the fresh resprouted milkweeds than on the older and taller control plants. In the strips mowed on July 1, peak egg densities occurred in late July; in the strips mowed in late July, peak egg densities occurred in early to mid August.” But it is important to remember that if you mow for monarchs, only mow patches or some strips so that older growth and other flowering plants will be available for adults and other pollinators.
Adult monarchs need sources of nectar to nourish them throughout the entire growing season and during migration. Try to include a variety of native flowering species with different bloom times to provide monarchs with the food they need to reproduce in the spring and summer and to migrate in the fall. Offering a wide array of native nectar plants will attract not only monarchs but other butterflies and pollinators to your habitat all season long. You can get a list of monarch nectar plants for your region from Xerces Society’s Monarch Nectar Guides.
In the last two decades, the eastern monarch population has declined by 80%. We still have a lot to learn about monarchs in order to protect them efficiently, and you can help! From July 24 to August 2, butterfly watchers across North America are invited to take part in the International Monarch Monitoring Blitz to help provide a valuable snapshot of monarch population status across their late summer range. Participation is simple: find a milkweed patch and look for monarchs, counting the number of stems you examined as well as the number of eggs, caterpillars, pupae, and adults. Then, share your observations with Mission Monarch. Visit Mission Monarch to learn more.
By Kent McFarland
Male and female Common Loons both tend to their young, feeding insects and minnows at first and larger fish later. Although loons will eat almost any fish they catch, perch are a favorite food. A loon’s average dive length is 35-40 seconds. Most fish are swallowed underwater with only the occasional larger fish brought to the surface. In a loon’s gizzard, which contains small stones, powerful enzymes and stomach acids help to digest the fish – bones included.
Adults guard their chicks during this period. Males might “yodel” at intruder loons or boaters who come too close. If intruder loons are present, chicks are often hidden near shore. The parents will also move the family to areas with less wind and wave action.
Common Loons will also eat live bait and lures from anglers. We routinely encounter loons tangled in fishing line, and loons that have ingested fishing line and bait. The results can often be fatal. Please “reel in” when loons are diving nearby and avoid using lead fishing gear of any kind.
Join the 38th Annual Vermont LoonWatch on July 18
Survey a lake for one hour on the third Saturday of July each year. If you’ve got time, survey a few lakes. On this single day, we cover more than 130 lakes and ponds statewide each year. It’s the single most effective way for VCE to document and track breeding loons across the state. To get an assignment for the annual LoonWatch, contact our loon biologist, Eric Hanson. Eric keeps a list of lakes where we need volunteers.
Here’s a map of the latest Common Loon sightings in Vermont from Vermont eBird, a project of the Vermont Atlas of Life. If you see loons, please report them to Vermont eBird and help us track their populations.
By Emily Anderson
“Careful, don’t open the door.”
After a long, hot day of kayaking, few things will keep me from rushing into the house for a cool shower. One of those few exceptions greeted me as I climbed my porch steps—a Luna Moth (Actias luna), perched precisely where door meets frame. I had seen pictures of them for years and found their faded wings in my yard, but shockingly had never encountered one in person. It’s said that a picture is worth a thousand words, however those words didn’t quite do justice to the delicate beauty of the moth in front of me. All thoughts of a shower gone, I leaned in closer, admiring its pastel mint green wings, the lower ones flowing elegantly like the hem of a shawl. Its eyespots were exquisite—each one looking like the details of a carefully painted children’s toy. However, what struck me most were its full, feathery antennae—intricate bristles on a miniature brush. About the size of my palm, this is by far one of the largest and most stunning moths I have seen to date.
It’s very surprising that I had never met a Luna Moth face-to-face before—after all, they’re fairly common and pretty hard to miss. This one was likely drawn to my porch light the previous night. While stunning, these moths only exist in this form for a short period of time. As adults, Luna Moths lack a mouth and digestive system and live for about a week, giving them just enough time to mate and lay eggs. If the adults’ main job is to mate, the caterpillars’ main job is to eat. Caterpillars are responsible for building up their fat reserves which will later keep them alive as an adult. They spend about a month eating the leaves on White Birch (Betula papyrifera) and Hickories (Carya) before spinning a papery brown cocoon out of leaves and silk. After three weeks in the cocoon, the newly-minted moth emerges, ready to find a mate and begin the cycle again.
Although Luna Moths are short-lived, they fill an important role in their deciduous forest ecosystem as a meal for others. While caterpillars may look unappetizing, they provide food for songbirds who aren’t deterred by their defense displays, clicking mandibles, and foul taste. As adults, they’re eaten by owls, whip-poor-wills, and bats. However, these fragile-looking moths are not defenseless—that swooping, twisted tail that I admired interferes with bats’ echolocation, making the moths harder to catch.
Finally, ready for the shady relief of my house, I gently coaxed the Luna Moth away from the door towards a place where it would be safe from treading feet. It moved slowly, reluctantly, making me wonder whether it had completed its mission and was now nearing the end of its life. I checked an hour later and it was gone. Perhaps it drifted away to shelter in the tangled forest nearby. Maybe, if I look out on my porch again the next night, I will find another one of these mysterious moon spirits waiting for its mate to arrive.
Although Luna Moth sightings often peak in June, their flight period lasts through mid-July, meaning that there’s still plenty of time to look. If you happen to encounter one of these otherworldly beauties, make sure to share your sighting with the Vermont Atlas of Life on iNaturalist! If you want to learn more about Luna Moths, check out their page on VAL or on Butterflies and Moths of North America.
National Moth Week celebrates the beauty, life cycles, and habitats of moths. “Moth-ers” of all ages and abilities are encouraged to learn about, observe, and document moths in their backyards, parks, and neighborhoods. Held worldwide during the last full week of July, National Moth Week offers everyone, everywhere a unique opportunity to become a citizen scientist and contribute information about moths. Through partnerships with major online biological data depositories, participants can help map moth distribution and provide needed information on other life history aspects around the globe.
You can help us celebrate moth week and collect valuable information about Vermont’s moth populations by taking part in our Vermont Moth Blitz. You can learn more about National Moth Week and the Moth Blitz here.