Maryland Grows

Butterflies in Maryland: Swallowtails and Checkerspots

In seasonal regions such as Maryland, nature goes through cycles, with some seasons reserved for growing and reproducing, and others for resting and waiting for conditions to get better. One of the groups of organisms that in my opinion represent clearly those changes in seasons are butterflies, which go through extreme modifications in their bodies and ecologies to closely match the changing seasons. Today’s post is going to explore two beautiful butterfly species that we can find right here in Maryland: the common Black Swallowtail and the beautiful but imperiled Baltimore Checkerspot.

First Things First: The Life Cycle of Butterflies

life cycle of butterflies

The life cycle of butterflies is fascinating and complex, and in our region is usually tightly linked with changes in season. Image: Kids Press Magazine

Before going into details about these butterflies, I think it is important to explain how these organisms develop because their life cycles are usually tightly related to our seasons. Caterpillars have indeed pretty special and fascinating life cycles. In these insects, a female lays eggs on the preferred host plant of the species. This way, the first larva (a tiny caterpillar) that emerges from that egg will not need to move far to feed on its favorite and most nutritious plant.

Once larvae hatch they start feeding on plant material, becoming bigger as they eat. Because insects such as butterflies are covered with a special hard ‘skin’ called an exoskeleton (this is really an external skeleton!) that gives them support and structure, every time the caterpillar gets too big, the exoskeleton becomes too tight (imagine a kid outgrowing a T-shirt). At that point, the caterpillar breaks the old exoskeleton and grows a new larger one in which it can fit.

While going through these ‘changes of skeleton’ (called molts), the caterpillar is able to grow until it is large enough to make their last change: pupation. At this stage, the very large caterpillar is ready to become an adult. For this, the caterpillar will molt a last time and become a pupa, which is the form that builds the cocoon in which the last body changes happen before the adult butterfly emerges.

As one can see, because the life cycle of butterflies has so many stages, there are many chances for things to go wrong during their development, which can also explain some annual fluctuations in butterfly populations. For example, if a wave of particularly cold or hot weather happened during one of the stages at which the caterpillars are sensitive (e.g., pupa, first instars), we may not see many butterflies later in the season. The same is true if there are important disease outbreaks, if predation was particularly high earlier in the season, if the host plants were not as abundant as other years, or if insecticides were applied close to some of the preferred host plants.

Now that we have a better idea of how the life cycle goes, let’s take a look at what our two species do and how they differ in their food preferences, life cycles, and how that affects how we can promote their presence in our surroundings.

Black Swallowtails

Even though it may seem obvious to some, let me start by saying that this species gets its name from the shape of its hind wings, which look like the pointy tails of swallows. Black Swallowtails (Papilio polyxenes) are common butterflies in our region and are present across the whole eastern USA.

In Maryland, this species has between two and three generations per year, with the first generation(s) of a season reaching adulthood within the season, and the last one spending the winter in pupal phase and emerging as an adult the following spring. (Check this other blog to learn more about butterflies in the winter: Where are all the pollinators?)

Like all butterflies, Black Swallowtails are specialized on what they feed. What defines what makes a plant yummy or not to the caterpillars are the chemical compounds the plant carries. In fact, plants have evolved to produce different chemical compounds that protect them against the multitude of herbivores that exist. Black Swallowtails in particular have evolved to tolerate the chemical compounds present in plants of the parsley family (Apiaceae). It is for this reason that these caterpillars can be found in your garden feeding on carrot, parsley, or dill leaves. Adults (butterflies) are usually seen collecting nectar from flowers such as clover, milkweed, and thistles.

swallowtail butterflies

Black Swallowtails can have several generations per year, feeding on plants of the carrot family, and finally emerging as beautiful adults either in the same or the following season. Photos: eggs (wikiCommons), larva (PINKE), pupa (Woodleywonderworld), adult (J. Flanery).

Black Swallowtails are currently considered to be a species that is not particularly at extinction risk. However, to maintain their populations it is recommended that open grasslands with plants that serve as caterpillar hosts are present. Interestingly, because they are so common in our area, they can be easily reared indoors, something that is really fun and can be a great summer project for kids (and adults!).

Baltimore Checkerspot

If Maryland has a state dessert, I feel it’s only fair that it also has a state insect! The Maryland state insect is the exquisite Baltimore Checkerspot (Euphydryas phaeton), which was chosen because its colors remind us of those of the Maryland flag. In our area, Baltimore Checkerspots are not as common as Black Swallowtails, and, unlike Swallowtails, have only one generation per year.

Their diets are also significantly more specialized than those of the Swallowtails: young caterpillars feed exclusively on white turtlehead, on which their eggs are laid. While later on in their development they are able to feed at least partially on alternative plants, white turtleheads are required for them to survive the early caterpillar stages.

Finally, unlike most butterflies in our region which spend the winter as pupae, this species spends its winter as a caterpillar and pupates only in the spring. The caterpillars of this species are super cute and they always remind me of the Dust Bunnies of the movie “My friend Totoro”. Adults of this species feed on milkweeds, dogbanes, and wild blackberries.

checkerspot butterfly caterpillars

Baltimore Checkerspots go through different developmental stages, hatching on their preferred host, and feeding on them as caterpillars, before entering pupal phase and finally emerging as adults. Photos: eggs (, larva (wikiCommons), pupa (, adult (S. Snyder).

Unfortunately, even though these beauties are our state insect, they are currently imperiled in our area. The reasons for this have to do with changes in land use, which led to less white turtleheads being available to the caterpillars both because less natural habitats are present and because the deer populations are so large that they eat most of the host plants!

If you would like to try to contribute to these butterflies’ populations, you can plant white turtleheads in your yard, but in particular support conservation actions already happening in Maryland, such as the Baltimore Checkerspot Recovery Team.  

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Time to think about fall planting!

Wait… what?

It seems like you’ve just put that spring vegetable garden in… though actually, come to think of it, there are tomatoes reddening and squash burgeoning and summer is in full swing. But still, fall seems a long time away. Can’t we wait to think about it until it gets chilly again?

Well, if all you want to grow in the fall are lettuce and radishes, and maybe some spinach, sure. Given our tendency to long, warm autumns, you may be enjoying your summer vegetables well into October, or even November, if we don’t get a hard frost, so who needs to plant anything else? But those long autumns also mean we have an ideal situation for keeping our production going into winter. And if you planted broccoli or cabbage or cilantro this spring, or any other plant that prefers cool weather, and were disappointed when it went to flower early or began to taste bitter, let me tell you: fall is better. Temperatures that start a little warmer for tender seedlings and grow gradually cooler, resulting in frost-kissed sweetness and beautiful greens or root vegetables–terrific! You just need to do a little work to get there. Read More

July Tips and Tasks

Japanese beetle

Japanese Beetle and damaged leaf

Japanese beetles may be feeding heavily at this time. Brush the beetles into a bucket of soapy water held underneath foliage or branches. The use of Japanese beetle traps near your plants is not recommended. Studies show that traps can attract more beetles to your landscape resulting in increased damage.

Crested iris

Crested Iris

Consider planting groundcovers where grass won’t grow such as shady areas, around tree roots, and on steep slopes. Select plants based on the amount of sun or shade the site receives.  



Sow seed for fall transplants of broccoli, kale, turnip, and cauliflower in flats or containers by the 3rd to 4th week in July. Late crops of squash, beans, and cucumbers can be direct sown into your garden through the end of July.

More tips and tasks for July

The Garden Hoes Podcast – Summertime Watering

Garden Hoes Podcast Player

As Dr. Wayne Dyer said, “The only difference between a flower and a weed is judgment.” June weeds are certainly testing our judgment. As we move into our third month of quarantine, our gardens are buzzing with activity. In this month’s episode, we discuss how to become garden detectives with Integrated Pest Management or IPM, fungal spots, timely watering tips, and our features for tip/bug/native plant of the month!

Integrated Pest Management (IPM) is a research-based holistic approach to pest management that emphasizes biological control versus the use of pesticides until absolutely necessary. In Maryland, we typically experience hot dry summers. Swiftly, our days merge from tranquil and breezy to sweltering and humid. During this time, our plants may show signs of decline. Making sure that they’re properly watered and taken care of will help ensure their survival. For more Watering Tips for Drought Conditions check out Factsheet HG85.


  • IPM – Start
  • Fungal Spots at (~6:55)
  • Watering Tips at (~10:00)
  • Native Plant of the Month at (~14:20) “Asclepias syriaca,” or common milkweed
  • Bug of the Month at (~20:00) “Water Strides” aka Jesus bugs
  • Garden Tips of the Month at (~23:00) “Bagworms, warm-season crop updates, and garden updates”

Click here to listen


The Garden Hoes Podcast is brought to you by the University of Maryland Extension. Hosts are Mikaela Boley- Senior Agent Associate (Talbot County) for Horticulture, Rachel Rhodes- Agent Associate for Horticulture (Queen Anne’s County), and Emily Zobel-Senior Agent Associate for Agriculture (Dorchester County).

Grow healthy, productive plants with the right supports

using plant supports in the garden

Washington County Master Gardener Karen Greeley (left) shows Elyse Phillips her garden which uses several types of plant supports.

Being supported is important. For you. For me. And for our garden plants.

The right garden supports help keep plants healthy. Lifting them up, up, up on stakes, cages and trellises boosts air circulation. This cuts down on rot and fungal disease.

Garden supports help keep heavy blooms from snapping stems. Is there anything worse than finding your prize delphinium prone in the morning, her poor neck broken by fierce wind?

Supports also expose vegetables and fruits to more sun, helping them to ripen faster. And they make picking easier, lessening knee and back strain.

Best of all, plant supports save space. Vertical gardening gives you a good harvest in a smaller footprint.

Place stakes, cages, and trellises early so plants are supported from the get-go. This avoids unpleasant wrangling of jungle-like growth later which is not good for you, your plants, or your resolution to avoid colorful language.

Anchor supports deeply to give them strength and stability when the inevitable high winds and rains come and plants grow large and heavy.

Some plants naturally cling with tendrils. Others need ties. Use a soft material like a strip of an old t-shirt, pantyhose, or reusable Velcro plant ties.

Plant supports can be store-bought or homemade. Use wood, bamboo, string, and other materials to make your own. Or hit your favorite local garden center, supercenter, or online store.

What type of supports are best?

Stakes are good for tall plants with a single flowering stem such as foxgloves or lilies. Some even come with hoops to lasso stems. My daddy staked his 10-foot tomatoes and harvested with a ladder. It was a point of pride.

But cages work better for heftier plants like tomatoes. Simply a frame with a grid, cages are good for shrubby edibles like tomatoes and eggplants.

I like square cages that fold flat for storage, but any sturdy cage will do. Steer clear of flimsy ones which tip over with the slightest provocation, also inducing colorful language.

Trellises are upright panels with criss-crossed wood or string. Both single panels and A-frames work well. In our demo garden, we use upright metal frames with string mesh.

Trellises are ideal for plants that twine or cling with tendrils such as peas, cucumbers, and pole beans. You can also use them for melons and squash provided you give the heavy fruits some extra support.

use a strip of fabric to support a melon on a trellis

Large fruits such as this cantaloupe can be supported on trellises with a wide strip of fabric.

That’s right, boys and girls. It’s time to talk about cantaloupe bras. Laugh if you will, but strips of my old t-shirt served well to lift and separate cantaloupes on our demo garden trellis.

Teepees provide both support and a pleasing focal point. Use them for vining plants or those that climb with tendrils. Make a fun kids’ teepee by growing beans and morning glories on a frame.

Hybrid supports work well for specific plants. Circles with grids and legs are terrific to prop up perennials with large, heavy flowers such as peonies.

Look up. Think up. And grow your plants up with the right supports.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.

Hidden Garden Party: Who’s Eating Whom?

aphids on cantelope leaf

Heavy aphid infestation on the underside of a cantaloupe leaf. Photo: Ashley Bodkins

Who loves a party? I know I do, especially a summer BBQ with all the family favorites! Insects are no exception and really know how to have some fun. Pictured above is a party of aphids, which are tiny little suckers — literally. They are soft bodied insects that suck plant sap with their piercing, sucking mouthparts.

aphid damage leaf curling

Twisted, deformed leaves are a symptom of aphid feeding damage. Photo: Ashley Bodkins

Aphids can come in many colors ranging from shades of green to black. They suck juice right from plant tissues, resulting in bent and twisted leaves as seen in the picture above. Aphids are generally only found on the underside of leaves and can be in very large numbers. Once a colony is established females can even reproduce without a male.

They secrete a sweet, sugary waste liquid that is called “honeydew”. Sometimes a fungus grows on the
honeydew, which is called sooty mold and looks like someone smeared coal soot on the plant.

Seeing ants on your plants can be your first sign that there is an aphid infestation. Ants love honeydew and often “farm” aphid colonies to reap the benefits.

ladybird beetle

The ladybird beetle is a natural enemy of aphids. Photo: Ashley Bodkins

Aphids can transmit plant virus diseases, but generally they aren’t found in large enough numbers to warrant a chemical control. Mother Nature actually Ahas some really interesting predators for aphids. In fact, the beautiful red with black spotted ladybird beetle (ladybug) is an avid aphid hunter and can eat more than 5,000 aphids throughout its four-part life cycle.

lady beetle larva eating an aphid

Ladybird beetle larva eating an aphid. Photo: Lenny Wells, University of Georgia,

Other natural predators include lacewings, flower fly larvae, and parasitic wasps. Evidence of natural predators include “aphid mummies” which are light brown, hollow aphid bodies that were once inhabited by parasitic wasp larvae.

aphid mummies

Mummies of oleander aphids parasitized by Aphidius sp. wasp. Note the hole in the aphid at the top right of the photo indicating a wasp has emerged. Photo: David Cappaert,

syrphid larva

Flower fly larva feeding on an oleander aphid. Photo: David Cappaert,

Physical control of aphids can be accomplished by spraying the pests with a strong stream of water. This causes them to fall off the plant and hopefully disrupt their feeding. As a last resort, use chemical
controls such as insecticidal soap or Pyrethrum products.

By Ashley Bodkins, Senior Agent Associate and Master Gardener Coordinator, Garrett County, Maryland, edited by Christa Carignan, Coordinator, Home & Garden Information Center, University of Maryland Extension. See more posts by Ashley and Christa.

Swarms, Swarms, and More Honeybee Swarms!

Swarm of bees on a branch

Photo by Anne Arundel County Master Gardener Beekeeping Project

On May 12, Nancy Allred, Interim Master Gardener Coordinator, Anne Arundel Co. called to say that one of the two Master Gardener Beekeeping Project hives at Hancock’s Resolution Park in Pasadena had swarmed. Swarming is the natural process that a honeybee colony uses to reproduce itself, so this is an exciting event. My husband and I packed up our bee jackets and drove to Hancock’s Resolution to check on the swarm.

Hancock’s Resolution is a historic farm park operated by the Friends of Hancock’s Resolution (FOHR) a 501(c) (3) non-profit organization. Under an agreement with Anne Arundel County Recreation and Parks, FOHR operates the farm and offers programming that interprets the site’s historical and agricultural significance. This remnant of a 410-acre middling plantation located in northern Anne Arundel County is on Bodkin Creek, near the mouth of the Patapsco River, and was once a well-situated market farm with close access to the Chesapeake Bay and the port towns of Baltimore and Annapolis.

Master Gardeners tend a demonstration garden and are on hand to discuss 18th-century farming practices, answer questions about plants, and invite visitors to participate in garden activities (however, activities and access are currently on hold due to COVID-19). Since 2009, Master Gardeners have tended the hives and provided pollinator educational programs that currently feature an observation hive that provides a view of the inner workings of a beehive.

Master Gardener beekeeper at Hancock's Resolution Park

Master Gardener beekeeper at Hancock’s Resolution Park – Photo courtesy

We were pleasantly surprised to see that the swarming bees had settled on the lower limb of a tree right next to the hives. Often swarms land just beyond the reach of your tallest ladder, so we were very lucky.

When swarming, the colony splits into two distinct colonies. The queen and about half of the workers (females) leave the hive in search of an appropriate site for their new home, often a large cavity in a tree. Typically the swarm temporarily settles on a tree or structure near the hive with the workers surrounding the queen in a cohesive “teardrop” of bees. Scouts fly off to find a suitable site for the colony, which might take a day or two or more. Once they identify a suitable site, the swarm takes to the air and follows the scouts to the new site. Meanwhile back in the original colony, the workers are busy raising several queens, one of which will become the new queen of the hive.

Tending the swarm

Photo by Anne Arundel County Master Gardener Beekeeping Project

In many cases, beekeepers are thrilled to see a swarm because if they can catch the swarm, they can add another colony to their apiary or replace a colony that died during the winter (in the last few years in Maryland, beekeepers have reported losing approximately half of all colonies each year — but that’s a topic for another article).

As Brian and I looked at the swarm that had settled next to the beehives at Hancock’s Resolution, we considered catching the swarm and setting up a new colony.  However, all of the Master Gardener hives at Hancock’s Resolution and Quiet Waters Park made it through the winter just fine, and our own colonies had also survived, so we had no place to install the new swarm. Unfortunately, you can’t just put the bees back into the hive that they came from since that hive is already down the path of raising a new queen.

Since we had nowhere to put the swarm, I called a fellow beekeeper, Charles DeBarber, to come collect the swarm. Charles has worked with John Conners and myself with the beekeepers at the Correctional Institution for Women in Jessup, including to help remove a swarm that had moved into an abandoned building there. Charles wears many hats, including maintaining about 20 hives at Filbert Street Community Garden in nearby Curtis Bay, and he sets up hives for other community gardens in the area. He was thrilled to have another colony to donate to a community garden.

Charles arrived at Hancock’s Resolution 20 minutes after I called him and a few minutes later had the bees in a small box called a nuc complete with frames of honey and honeycomb to make them feel at home. The swarm was very gentle and only focused on protecting the queen who was somewhere in the middle of the ball of bees. Charles was able to collect the swarm without protective gear (don’t try this at home!) and no one got stung during this process. When Charles left, he was headed to a community garden to move the “ladies” into their new home.

Tending the swarm

Photo by Anne Arundel County Master Gardener Beekeeping Project

But that wasn’t the end of this story. The next day Nancy called again to say that ANOTHER swarm had appeared in the same location. Was it from the other hive, the same hive, or another hive in the neighborhood? There’s no way to know, but we suspect that it was from the other hive. Once again, we made the trip out to Hancock’s Resolution, called Charles, and got the second swarm (which was even larger than the first) dropped into another box to be delivered to its new home.

But, still, there’s more to the story.On May 22, ten days after Nancy called about the first swarm, she called again reporting a THIRD swarm. Once again, Charles showed up and retrieved the swarm and took it to a local community garden that was grateful to have such hardworking pollinators near their garden plots.

In the meantime, the Master Gardener Beekeeping Project honeybees at Hancock’s Resolution and Quiet Waters Park are thriving, collecting lots of nectar and pollen, raising young, and making sure that the hives have enough honey and pollen to survive the next Maryland winter.

It is a wonderful thing to support and help pollinators thrive. The transfer of pollen from the male organ to the female organ of a flowering plant – is essential to life on earth, for without pollination most people and non-human animals would not have enough food. Over 90% of all known flowering plants, and almost all fruits, vegetables and grains, require pollination to produce crops. Happily, there is a pollinator volunteer workforce that includes bees that does this job for us.

If you find a swarm on your property, you can find a beekeeper via Maryland Beekeepers Association to come and save it.

Pam McFarland, Anne Arundel County Master Gardener, University of Maryland Extension. Edited by Dan Adler.