Category Archives: Phenology

Tiny Hemlock Pest Has Hatched

Insects, Fish, Frogs, Phenology, Trees
Hemlock woolly adelgid nymphs (photo by Elizabeth Benton, University of Georgia, Bugwood.org)

A week ago I received a message from the USA National Phenology Network that hemlock woolly adelgids would hatch very soon in Pittsburgh and the southern Appalachians. This is worrisome because the nymphs are the active phase of this forest pest.

Hemlock woolly adelgid hatch announcement from USA NPN

Originally from Japan, hemlock woolly adelgids (Adelges tsugae) kill eastern hemlocks in 4-20 years by locking on where the needle meets the stem and sucking the lifeblood out of the tree (closeup at top).

The adults are sedentary, attached to a tree. The nymphs, however, are tiny and mobile. They blow on the wind and hitchhike on clothes, equipment, birds and animals. They spread very easily just after they’ve hatched.

The message above says “You should see active nymphs” but you won’t. At 1/100th of an inch they’re smaller than a grain of sand, almost microscopic. And yet, their effect is devastating.

Hemlock woolly adelgids have already killed up to 80% of the hemlocks on parts of the Blue Ridge Parkway and in Shenandoah National Park. They are eating their way through the Great Smoky Mountains, shown below, and they’re killing hemlocks in Pennsylvania.

Tree death from Hemlock woolly adelgid in the Great Smoky Mountains (photo by Ignazio Graziosi, University of Kentucky, Bugwood.org)

We won’t know how far they’ve spread this spring until they reveal their presence next fall when the females deposit woolly egg sacs on the undersides of hemlock branches.

Hemlock woolly adelgid eggs covered in white “wool” (photo by Steven Katovich, USDA Forest Service, Bugwood.org)

Right now the nymphs are spreading.

Read more about hemlock woolly adelgids at the USA National Phenology Network.

(photos from Bugwood’s invasive.org, message and map from USANPN. Click on the captions to see the originals)

Now Blooming

Phenology, Plants, Schenley Park
Bluets at Raccoon Creek Wildflower Reserve, 16 April 2019 (photo by Kate St. John)

20 April 2019

Wildflowers are blooming, elms are setting seed, and some early trees are leafing out. Here’s a sampling of buds and blooms this week in southwestern Pennsylvania.

At Raccoon Wildflower Reserve on Tuesday our group found many flowers opening including bluets (above) and early saxifrage (below). Our complete list is at the end.

Early saxifrage at Raccoon Creek Wildflower Reserve, 16 April 2019 (photo by Kate St. John)

The trail at Racoon Wildflower Reserve was littered with the tips of sugar maple branches, chiseled off by squirrels. These Acer saccharum buds are opening to reveal new flowers.

Sugar maple bud opening at Raccoon Creek Wildflower Reserve, 16 April 2019 (photo by Kate St. John)

Meanwhile in the City where it’s warmer …

This spruce in Shadyside was flowering, too. The pink buds will become cones.

American elms (Ulmus americana) have already set seed. You can tell this is an American (not slippery) elm because the samaras are deeply notched.

American elm samaras from Schenley Park, 16 April 2019 (photo by Kate St. John)

In Schenley Park, invasive Norway maples (Acer platanoides) are leafing out.

Norway maple leaf-out in Schenley Park, 17 April 2019 (photo by Kate St. John)

Spend time outdoors this weekend and see what’s blooming near you.

Here’s are list of flowers seen at Raccoon Wildflower Reserve on Tuesday 16 April 2019, in no particular order. Many flowers were only beginning to open. By now they’ll be in full bloom.

(photos by Kate St. John)

Late April: What’s Next?

Migration, Phenology
Great horned owl with yawning nestling, April 2019 (photo by Dana Nesiti)

Spring is popping in southwestern Pennsylvania. Here’s what to look for in late April.

  • Branching! Great horned owlets are growing up fast. At the earliest nests owlets will walk on nearby branches before the leaves come out. Dana Nesiti photographed this yawning owlet in early April.
  • Nest building: Songbirds are building nests especially American robins, song sparrows and Carolina wrens. House sparrows flutter by with cellophane for their nests.
  • Migration: Blackbirds and tree swallows are here. Gray catbirds are coming soon. Also Louisiana waterthrush, yellow-throated warbler, hermit thrush, ruby-crowned kinglet, blue-headed vireo, brown thrasher, blue-gray gnatcatcher, pine warbler, northern parula, chimney swift, barn swallow and house wren. See them on an outing with the Three Rivers Birding Club.
  • Trees: Flowering trees include redbud, downy serviceberry, cherry and more. “Leaf out” comes in early May.
  • Wildflowers: Violets, large-flowered trillium, trout lilies, Virginia bluebells and much more. Get outdoors with the Botanical Society of Western PA or Wissahickon Nature Club. Visit Enlow Fork on the last Sunday in April for the Enlow Fork Extravaganza starting at 8:00am.
  • Butterflies: Spring azures, cabbage whites, eastern commas, orange sulphurs, red admirals.
  • Turkey season: Be careful if you hear a turkey calling; it might be a hunter. Spring Gobbler hunting season runs from the last Saturday in April through all of May. Junior hunters get a one-day early start on the next-to-last Saturday (April 20).

In late April, spring is happening fast. Don’t miss it!

(photo by Dana Nesiti)

Red Maples Are Complicated

Phenology, Schenley Park, Trees
Male red maple flowers fallen from the tree, 10 April 2019 (photo by Kate St. John)

This week the hillsides turned faintly red as red maples (Acer rubrum) bloomed across southwestern Pennsylvania. The city’s maples bloom sooner than the suburbs so I’ve had a preview of what’s to come.

In Schenley Park the ground under some red maples is carpeted with fallen flowers (above) while others retain flowers that are setting seed (below).

Female red maple flowers on the tree, developing samaras, 10 April 2019 (photo by Kate St. John)

That’s because red maples are sexually complicated. They are polygamodioecious which means some trees have only male flowers, some have only female, and some have both (i.e. hermaphroditic). And they can even switch back and forth:

Under the proper conditions, the tree can sometimes switch from male to female, male to hermaphroditic, and hermaphroditic to female.

Wikipedia Acer Rubrum

Watch your local red maples to see what they’re up to. The one in my backyard dropped its flowers a few days ago. This year it’s a male. 😉

p.s. For more on maple phenology, read Chuck Tague’s blog post: Maples In Spring: A Study in Diversity.

(photos by Kate St. John)

Now Blooming

Phenology, Plants, Schenley Park
Hepatica at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

What’s blooming in southwestern Pennsylvania this weekend?

Yesterday’s joint outing of the Botanical Society of Western PA and Wissahickon Nature Club found a lot of spring flowers at Cedar Creek Park in Westmoreland County, 6 April 2019.

Hepatica was blooming in shades of white, pink and blue. In the photo above, the leaves aren’t visible so I can’t tell if this plant is round-lobed (Anemone americana) or sharp-lobed (Anemone acutiloba) hepatica.

Harbinger of Spring (Erigenia bulbosa) was blooming along the valley trail. Did you know this plant is in the Carrot family?

Harbinger of spring at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

Snow trillium (Trillium nivale) covered the hillside beyond the last bridge …

Snow trillium at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

… and spicebush’s (Lindera benzoin) tiny yellow flowers were a nice surprise.

Spicebush at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

Most of the spring beauty was not in bloom but we found Carolina spring beauty (Claytonia caroliniana), a specialty at Cedar Creek shown below.

Spring Beauty at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

This bloodroot (Sanguinaria canadensis) was bright white by the bike trail. Its leaves are barely visible, clutching the stem, while a garlic mustard leaf tries to photo-bomb the bottom corner.

Bloodroot at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

Meanwhile, how are the buckeye buds doing in Schenley Park? Some were unfurling on Friday 5 April 2019. Note the CORRECTION ABOUT BUCKEYES below!

Yellow buckeye buds, starting to unfurl their leaves in Schenley Park, 5 April 2019 (photo by Kate St. John)

CORRECTION ABOUT BUCKEYES: Last week Stephen Tirone investigated the buckeye buds in Schenley and Frick Parks and learned that these are yellow buckeyes (Aesculus flava) not Ohio buckeyes (Aesculus glabra). Though Ohio buckeyes are more common in the wild, Pittsburgh’s parks are not “wild.” Schenley and Frick Parks were landscaped with ornamentals when the parks were established more than 100 years ago. Yellow buckeyes are often planted as ornamental trees and may be hybridized to produce showy flowers. So, yes, these are yellow buckeyes.

(photos by Kate St. John)

Pennsylvania Fire Season

Phenology, Weather & Sky
Fire in the Wayne National Forest, March 2009 (photo from Wikimedia Commons)

Spring is fire season in Pennsylvania. 85% of our wildfires occur in March, April and May.

There’s no drought in Pennsylvania right now, nor in most of the U.S. — as shown on the map below.

US Drought Monitor for 28 March 2019

But you don’t need drought to have a fire. All you need are dry conditions, fuel, and a spark. In Pennsylvania we have all three in the spring: low humidity, gusty winds, and lots of old leaf litter drying out in the sun. The spark comes from people.

98% of Pennsylvania’s wildfires are caused by people and most of those are caused by people burning debris. On a sunny windy day those fires blow onto dry grass and escape to the wild. In April 2016 more than 10,000 acres burned in Pennsylvania.

Yesterday the fire danger was high in our state because the weather was so nice — warm and sunny with gusty winds. Across Pennsylvania people were out doing yard work. Some were probably burning piles of debris. I haven’t heard if there were any fires. (The fire danger is lower today, 4 April 2019, because the weather changed.)

U.S. Forest Service Wildfire Danger Forecast

If you live in a place that allows outdoor trash burning be careful out there! Spring is Pennsylvania fire season.

(photo of fire from Wikimedia Commons (actually a prescribed burn). Maps from US Drought Monitor and U.S. Forest Service Wildfire Danger Forecast; Click on the captions to see the originals)

Note: Allegheny County does not allow outdoor trash burning.

Buds About To Burst

Phenology, Schenley Park, Trees
Yellow buckeye buds about to burst, 1 April 2019 (photo by Kate St. John)

Yesterday I found these buds about to burst in Schenley Park.

Yellow buckeyes (Aesculus flava) are one of the first trees to leaf out in the spring, unfurling their dramatic palmate leaves. They’re such a welcome splash of green that I photograph them nearly every year. This is the first time I noticed the bud at this stage. I didn’t expect it to be red.

Over the years my buckeye photographs have documented the vagaries of spring in Schenley Park. In cooler years — such as 2015 — the buds weren’t this far along in mid-April. Here’s a closed bud on 15 April 2015.

Closed bud on 15 April 2015 (photo by Kate St. John)

In hot years — such as 2012 — the buds opened weeks ahead of schedule. This buckeye was completely leafed on 19 March 2012.

Yellow buckeye tree 19 March 2012 (photo by Kate St. John)

This year appears to be a “normal” spring … whatever that means these days.

(photos by Kate St. John)

Late March in Schenley Park

Phenology, Plants, Schenley Park
  • Cornelian cherry (Cornus mas), 28 March 2019 (photo by Kate St. John)

Spring is coming at a good pace this year. Unlike hot years, such as March 2012, there’s time to appreciate each new leaf and flower before the next set appears.

My photos above show a selection of leaves and flowers at Schenley Park this past week. Most were taken on March 28 but the real surprise was coltsfoot blooming on St. Patrick’s Day. That flower hid for ten days and appeared again last week.

Unfortunately, all of these plants are alien and some are invasive. Their ability to spring ahead of the local plants gives them an advantage all year long.

Click here for that same honeysuckle branch, bud-to-leaves on March 11, 16.

(photos by Kate St. John)

The Trees Are Snowing

Phenology, Trees, Winter Weeds & Trees
Drift of fluffy seeds from London plane trees, 17 March 2019 (photo by Kate St. John)

Last week I found fluffy drifts on the sidewalks in my neighborhood. They’re the airborne seeds of London plane trees (Platanus × acerifolia), planted in Pittsburgh in the late 1800s because they’re tolerant of air pollution.

Like their parents — oriental plane tree (Platanus orientalis) + American sycamore (Platanus occidentalis) — London plane trees retain their dangling seed balls over the winter.

London plane tree fruit in autumn (photo from Wikimedia Commons)

Then in the first warmth and light of spring the seed balls disintegrate and the seeds blow away. You’ll find drifts near American sycamores, too.

London plane tree fruit disintegrating (photo from Wikimedia Commons)

In March the trees are snowing.

(seed drift photo by Kate St. John; remaining photos from Wikimedia Commons, click on the images to see the original)