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Escaping the August heat in the high elevations of the Green Mountains. K.P. McFarland

Field Guide to August 2021

The dog days of August are here. Insects are buzzing and summer's bounty is plentiful. But migration is underway alerting us to the coming changes.

By Vermont Center for Ecostudies August 2, 2021
Katydid perched on a fence rail at night. © K.P. McFarland
Katydid perched on a fence rail at night. © K.P. McFarland

Calling Crickets and Katydids

By Kent McFarland

Crickets and katydids can evoke childhood memories of summer as we pause to listen to their distinct sound. Known to biologists as the order Orthoptera (or-THOP-tir-ah), they can be found all over the world, except at the poles. In Vermont there are 35 known species—15 crickets (one introduced species) and 20 katydids (three introduced species).

Stridulation

Katydids front wings feature a file and a scraper. The file looks a little like the teeth of a comb, and the scraper is just a sharp edge. To produce their familiar sound, they elevate their front wings and move them back and forth against each other, the scraper on one wing moving along the file of the other. This action makes membranes on the wings vibrate, which is the source of the sound we’ve been hearing since we were kids.

And, they listen to the sound with their legs. Katydids don’t have ears on the sides of their heads like we do, they have them on their knees… or their elbows… either way—they have an ear-like structure called a tympanum, which is a tiny oval cavity with a thin membrane stretched over it that vibrates in response to sound, much like our own eardrum.

Listen to Outdoor Radio to learn more about how crickets and katydids sing and the surprising way that they hear. Hold a leg up and listen to the show.

Make recordings of these insects with your smartphone and the iNaturalist app and upload them to our Vermont Atlas of Life project on iNaturalist.

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Dictyostelium discoideum "slug" stalk and spore structures © Usman Bashir
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Slime Mold and small mushrooms © Julia Pupko

Smart Slime (Mold)

By Julia Pupko

While strolling through the woods following some heavy rain, I stumbled across a mossy log covered in small mushrooms. I stopped to enjoy the diversity displayed on the decomposing log, and noticed someone who I had missed in my initial examination—a slime mold!

Slime molds were once thought to be a fungus (molds are fungus), but that turned out to be far from the truth. Slime molds are amoebas and are now included in the Kingdom Protista; they are single-celled organisms with multiple nuclei, with many growing large enough to be easily seen with the naked eye. They range in size from microscopic to 13 feet! Over 900 species exist across the world. They are able to move and consume microorganisms, such as yeasts, bacteria, and fungi, that live on decomposing plant material.

There are several different groups of slime molds: 1) plasmodial slime molds or Myxogastria (amoeboflagellates; usually large, multi-nuclear cells), 2) cellular slime molds or Dictyostelia (amoebiod), and 3) Protostelia slime molds (microscopic for the most part).

Cellular slime molds, the second largest group of slime molds, have fascinating reproductive strategies based on their environmental conditions. If environmental conditions are favorable and food is ample, cellular slime molds such as Dictyostelium discoideum can reproduce asexually as individuals and continue on with their lives.

However, when conditions are unfavorable, Dictyostelium discoideum and other cellular slime molds form “slugs,” each containing a single nucleus. To reproduce, they crawl along the ground, leaving a trail of chemicals behind them. Other “slugs” of the same species find the trail and follow it, leaving behind their own chemical trace, making the chemical beacon stronger and thereby attracting more “slugs.” Once enough individual slime mold slugs have congregated, they fuse together to reproduce, with different individual slime slugs taking on different roles in the reproductive process, together forming a single stalked spore producing structure. Around one third of the individuals form the stalk and do not get to reproduce, dying in the process of spore structure formation. Through creation of a tall stalk, they collectively have a higher chance of survival since spores will be able to disperse farther, hopefully to more favorable conditions.

Slime molds have been found to be capable of making computations, such as determining the least energetically costly route to food and solving mazes (not to mention their reproductive decision), and do all of this without a brain. Additionally, slime molds have incredible genetic editing abilities, changing their DNA while copying it during growth. Different slime mold groups have different strategies for overcoming environmental adversity and meeting their needs, many demonstrating the power of collective swarm behavior between individuals or within a single individual. Keep your eyes out for these cool organisms, especially when there are many dead, moist logs around!

11596, , squash-longhorn-cuckoo-bee_580x400_acf_cropped, , , image/jpeg, https://vtecostudies.org/wp-content/uploads/2021/07/squash-longhorn-cuckoo-bee_580x400_acf_cropped.jpeg, 580, 400, Array, Array © Spencer Hardy
Squash Longhorn-Cuckoo (Triepeolus remigatus) © Spencer Hardy
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Pruinose Squash Bee (Peponapis pruinosa) © K.P. McFarland

A Cleptoparasite in the Garden

By Spencer Hardy

Despite the name, the Squash Longhorn-Cuckoo, it’s not a vegetable, cattle from Texas, or a bird. It’s actually a bee. Taxonomists call it Triepeolus remigatus and it’s a cleptoparasite of the Pruinose Squash Bee (Peponapis pruinosa). Squash bees are in the Longhorn Bee family and are specialists that only collect pollen from the flowers of a few species of Cucurbits (cucumber, melon, and squash), which in Vermont means they are only found near farms and gardens. As a cleptoparasite of a squash specialist, the Squash Longhorn-Cuckoo also feeds its young entirely squash pollen, but relies on female Squash Bees to collect the pollen. Once the Squash Bee has established a nest and provisioned it with balls of pollen, female Longhorn-Cuckoos show up and sneak into the nests to lay their eggs (like a Brown-headed Cowbird). August is a great month to look for both these species—the Squash Bee can often be found statewide in gardens with only a few zucchini or winter squash, while the Longhorn-Cuckoo is only known from Chittenden and Washington counties so far, though is worth looking for near farms and community gardens with sandy soil (which is the preferred nesting substrate of its host). Learn more about these species at the Vermont Atlas of Life Wild Bee Survey and add your observation to our iNaturalist project.

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Juvenile Bald Eagle © Nathaniel Sharp
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Bald Eagle - adult plumage © Nathaniel Sharp

First Flight

By Julia Pupko

By August, many of the young animals that were birthed or hatched this season are reaching maturity, and many will soon be venturing off on their own. In Vermont, most Bald Eagles (Haliaeetus leucocephalus) have hatched their young by the end of May, meaning that the young eagles will fledge between July and August. At this point, the young begin to learn how to fly by gliding to branches and other perches below the nest. Gradually, they will increase the distance of their flights as they build confidence. During this time, the young will continue returning to the nest and receiving food from their parents, while also learning how to hunt. They typically remain with their parents for another month before becoming fully independent.

Young Bald Eagles are mottled brown in color, not developing the classic white head and tail feathers until around the time they become sexually mature, which is at 5 years of age. They mate for life, only taking a new mate if one of the pair dies. One fun fact is that Bald Eagles use the same nest for many years, adding to it every breeding season. Nests have been recorded to be 10 feet in diameter and can weigh several tons!

Keep your eyes out for entirely brown Bald Eagles that appear clumsyyou may be looking at a fledgling from this year! Report your observations to Vermont eBird.

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Eremnophila aureonotata © Bernie Paquette
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Gold-marked Thread-waisted Wasp dragging a paralyzed Angulose Prominent © Julia Pupko

Wasp Snacks

By Julia Pupko and Kent McFarland

While sitting outside writing this blog post, I received some unexpected inspiration. A Gold-marked Thread-waisted Wasp (Eremnophila aureonotata) dragging an Angulose Prominent (Peridea angulosa) caterpillar through the grass (see my super poor quality photo above). This wasp was on her way back to her nest, bringing the caterpillar along as food for her young. Gold-marked Thread-waisted Wasps dig burrows into sandy or loamy soils, using their mandibles and heads to excavate soil. They will then press their head against the side of the burrow and vibrate their bodies to pack it down. Most Thread-waisted wasps create burrows in soil, and will then close off the entrance to their nest once it is completed with young and prey. Some species have been observed using small rocks as a tool to pack down the closed-off entrance to their nest.

This wasp inhabits old fields near deciduous woodlands, and can commonly be found on wild flowers that have “large clusters of blooms, such as Queen Anne’s Lace” (BugGuide.net). As adults, they primarily eat nectar, but may also prey on small insects that they catch in the air. Gold-marked Thread-waisted Wasps seem to be most commonly found between July and August, so keep an eye out for these fascinating insects this August!

Cerceris fumipennis carrying a Buprestid beetle.  © K.P. McFarland
Cerceris fumipennis carrying a Buprestid beetle. © K.P. McFarland

The Smoky-winged Beetle Bandit (Cerceris fumipennis) hunts for Jewel Beetles (Buprestidae). This wasp is a solitary ground-nesting species. Each female constructs and attempts to maintain a single subterranean nest. The nest is usually in loose soil or sand and in close proximity to others, forming a neighborhood. The nest’s entrance is easily visible, marked by a small circular mound of earth with a pencil-sized hole in the center.

A female wasp attacks its target by landing on it and grabbing it by the thorax with her mandibles. She then inserts her stinger in a gap in the beetle’s armor at the base of its leg and injects a paralytic venom. The wasp flies back to the nest with the beetle tucked under her body like a torpedo. She places each beetle in a small chamber and lays an egg on it before closing it off with a plug of dirt. The wasp larvae feed on the live beetle. Ten months later, the wasps emerge from the ground to mate and raise their young.

The wasp has an enemy to avoid. Female “satellite flies” (Miltogramminae) intercept prey-laden wasps and deposit eggs on the paralyzed beetles. The voracious fly maggots out compete the developing wasp larvae for paralyzed beetle food and the wasp larva dies of starvation. While netting bees for the Vermont Wild Bee survey, VCE biologist Spencer Hardy swung his net at a flyby wasp and managed to capture all 3 insects involved in this fascinating interaction. Check out his iNaturalist observation including a Smokey-winged Beetle Bandit, Buprestid beetle, and a couple of satellite flies. 

Like police recruiting dogs for sniffing out illegal drugs, biologists have used this wasp to search for an introduced beetle called the Emerald Ash Borer (Agrilus planipennis). The first detection of this beetle in Connecticut was at a wasp nest under biosurveillance.  Read more about Cerceris wasps from Northern Woodlands online, and check out more of Kent’s awesome images of these amazing insects.

Great Golden Digger Wasp (Sphex ichneumoneus) carrying a katydid.  © K.P. McFarland
Great Golden Digger Wasp (Sphex ichneumoneus) carrying a katydid. © K.P. McFarland

Great Golden Digger Wasps (Sphex ichneumoneus) hunt for grasshoppers, katydids or crickets. With a sting, they paralyze their prey, place it in an underground chamber, and lay one egg on it. The victim stays alive, providing fresh food for the hatching larva to feed upon. House Sparrows (Passer domesticus) and American Robins (Turdus migratorius) have been observed chasing wasps carrying prey to their nests, causing them to drop the food, which the birds then grabbed and ate. The wasps produce one generation per year. The young wasps spend the winter in their nests and emerge the following summer.

Monarch fueling up on Joe Pye Weed before migration. © K.P. McFarland
Monarch fueling up on Joe Pye Weed before migration. © K.P. McFarland

Monarchs Migrate with a Compass

By Kent McFarland

How do Monarchs hatched in Vermont navigate to Mexico where their great-great-great-great grandparents wintered? Recent research has shown that Monarchs use a time-compensated “sun compass” to maintain a southwesterly direction during flight.

The winter generation of butterflies lives up to eight months while the successive spring and summer generations are lucky to live a single month. It takes four or five generations of spring and summer Monarchs to produce the final “super generation,” which migrates to Mexico in the fall and then back to the southern United States in spring.

So how do they travel thousands of miles and arrive at a tiny area in the mountains of central Mexico? Monarchs monitor the position of the sun with their eyes. But that’s not enough because the sun changes position like clockwork. They also need to know the time of day. Monarchs have an internal clock based on the rhythmic expression of key genes. The clock is centered in the antennae of the butterfly. The Monarch’s brain takes the information from the eyes and the antenna and  integrates the time of day with the sun’s position in the sky to derive direction.

How do we know that Vermont Monarchs actually make it to Mexico? One way is by tagging them. With millions of Monarchs, the odds of a recapture are poor; however, there have been at least eight tagged Monarchs from Vermont found in Mexico. The first lucky tag was applied in Essex Junction on September 9, 1999, and the monarch was found in El Rosario, Mexico on March 1st, 2,320 miles away!

We also know that Monarchs from the Northeast winter in Mexico by testing their chemistry. Hydrogen isotope analysis shows that New England monarchs winter in Mexico. Rainwater contains slightly different amounts of these isotopes across North America, and this unique chemical signature is transferred from rainwater to milkweed to caterpillars to adult Monarchs. By selecting sites scattered across eastern North America, researchers have created a map displaying the chemical levels for each region. One study found that on average, only about 15% of the Monarchs overwintering in Mexico originated in the Northeast, while 38% are from the Upper Midwest.

Get Involved

It’s time for Mission Monarch across North America! Have you added a Monarch survey yet? It is so easy to do and takes as little as 15 minutes of your time! Find a milkweed patch of any size anywhere, survey the plants for eggs and caterpillars, add your data to Mission Monarch!  And when Monarch migration begins, add your Monarch butterfly sightings to Journey North, eButterfly, or iNaturalist and help track their travels to Mexico.

11571, , large (3), , , image/jpeg, https://vtecostudies.org/wp-content/uploads/2021/07/large-3.jpeg, 768, 1024, Array, Array © Nathaniel Sharp
Blackberries (Rubus genus) © Nathaniel Sharp
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Wild Grapes (Vitis genus) © K.P. McFarland

August Foraging

By Julia Pupko

One of my favorite things about the summer is the fact that I am able to snack basically everywhere I walk. Here are some tasty treats to keep your eyes out for this month:

 
Always remember to be positive of your identification before eating something. When in doubt, don’t eat it. Even in Vermont, misidentification mistakes can be fatal. On that morbid note, happy foraging!

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