Milkweed Bugs?

Large Milkweed Bug (Oncopeltus fasciatus) on a milkweed seed pod.

     I have always been fascinated by milkweed communities and all the adaptations that allow their inhabitants to survive there. Planting milkweeds for monarchs is getting more popular today, but many other creatures also benefit from milkweed (and many other plants can also be as good or better at providing backyard habitat as milkweeds). I am fairly familiar with these food webs, including the interesting bugs that inhabit them. But one of the things I love about my being a naturalist is that you learn new things just about every day. That was the case with these fairly well-studied insects which I will describe to you.

     First of all, milkweed bugs are brightly colored insects with sucking mouth parts that have evolved to (mostly) live on milkweeds. The toxins that normally protect the milkweeds (cardiac glycosides) are absorbed and used to then protect the milkweed bugs that feed on them. They advertise their toxicity with bright colors, like many milkweed feeding specialists do.

     Large Milkweed Bugs (Oncopeltus fasciatus) are one of the most studied insects in science. They prefer to feed on milkweed seeds, but can be reared on other types of seeds. They are thus easy to keep and are used in many science experiments. Those that do not feed on milkweed retain the warning coloration, but are not toxic. Adults are one of the few migratory insects we have, normally heading South during the Fall. They are distinguished from the other milkweed bugs by their larger size and the dark band across their backs.

Small Milkweed Bug (Lygaeus kalmii)

     Small Milkweed Bugs (Lygaeus kalmii) have a similar life cycle, but are more apt to feed on things other than milkweeds and do not migrate. They also will nectar on flowers, as you can see by the one in the picture feeding on Queen Anne's Lace. They are distinguished from other milkweed bugs, as most identification books tell you, by the "X" across there backs. However, it is also, I now know, good to look for the heart-shaped mark above the "X." 

False Milkweed Bug (Lygaeus turcicus)

     What most books do not tell you is that there are other species of milkweed bugs and that even many experts sometimes misidentify another milkweed bug for the Small Milkweed Bug. I discovered this for myself not too long ago when I spotted some milkweed bugs, but noticed that something wasn't quite right. First of all, most were not on milkweeds. That in and by itself is not as big a deal since milkweed bugs sometimes feed on other plants, as I have mentioned. But they also didn't look quite right and were also concentrated on False Sunflowers rather than the milkweeds that were right next to them. I snapped a couple of photos and that was that.

False Milkweed Bugs mating.

     However when I looked at my photos again, I realized that none of them were on milkweed and that they were mating, but not interested in the milkweeds. I then also saw that though I had Large Milkweed Bugs, that I appeared to have two other milkweed bugs that had slightly different patterns on their backs, including many that did not have the heart-shaped mark above the "X" that should have been there.

     A bit of research later, plus sending my photos to the experts at Bug Guide for confirmation, had me finding out that there was indeed another local milkweed bug that I had never heard about until I looked for it. I had now learned about False Milkweed Bugs, a species that is mistaken for Small Milkweed Bugs sometimes even by experts and in books/online photos. Although they can feed on milkweeds, they also feed on a variety of other plants as well. The mark they have above the "X" is slightly different from the heart-shaped one in the actual Small Milkweed Bug. 

     Most of my professional life I had been looking at not two, but three different species with somewhat different life cycles and niches in the natural world, despite my thinking I was fairly well versed in milkweed communities, or at least these fairly well-known creatures. That again is one of the things I love about my profession, the new discoveries, especially when they are triggered by my curiosity or when I notice something different. I love these little mysteries and when I learn something new, as I try to sort out what I consider to be nature's interconnected and fascinating puzzle. 

Black Gray Squirrels?

Black colored Gray Squirrel

     I have been asked many times by people about the black squirrels we have in the DC area. Though they are actually just melanistic versions and the same species (Scirius carolinensis) as the regular Northern Gray Squirrels, they actually have an interesting history behind them. I thought a little bit of natural history history might interest folks.

Northern Gray Squirrel, the typical backyard squirrel around here

     As I stated before, the black squirrels are actually the same species as the normal backyard squirrels we have all around and can freely interbreed with them. They were purposely reintroduced, along with the "normal" gray squirrels, back into the DC area in the early 1900's after there was concern that there wouldn't be any squirrels of any type around any more locally, that they had been close to being extirpated. Gray squirrels were indeed very rare, having been mostly hunted out long before. By 1906, hunting was prohibited within the city and people wanted to bring them back, believing they would be great additions to parks. 

     So gray squirrels were released at several DC parks such as Lafayette Park. They were fed by people and even by Park Police. Teddy Roosevelt, who had quite a menagerie of pets anyways and loved squirrels in general (he had flying squirrels at his cabin for instance), had them released at the White House in 1907 as well. A great movement to reintroduce them was succeeding.

Both a normal gray and black gray squirrel share a tree in Arlington, Virginia.

     But what about the black squirrels? These may also be a result of Teddy Roosevelt. It seems that in both 1902 and 1906, 18 black squirrels were brought to the National Zoo from Ontario, Canada. Black squirrels are much more common there, likely because the dark color gives them a heat advantage that offsets any disadvantage from their not being able to hide as well. These 18 dark squirrels were released from the zoo sometime after 1906. By 1917, the first road kill of a black squirrel was recorded. 

     So the National Zoo became ground zero for these darker squirrels. Since there were not as many "regular" gray colored squirrels and the black ones may have had a heating advantage (and no predators were around to hunt them), the recessive dark genes were allowed to establish themselves in the population. Now almost half the squirrels around the zoo are black or darker in coloration.

     Being protected and well fed, squirrel populations exploded. In fact, a 1980's study resulted in the claim that no where else on earth were there squirrels more densely populated than Lafayette Park. The black squirrels also continued to spread, by the 1980's being found in some numbers in Arlington, Virginia and parts of Maryland. Now up to a fourth of the squirrels in these locations are dark. 

     Squirrels are of course rodents, and breed as fast as many rodents do. They have spread and their numbers now can be quite abundant. "Tree rats" in fact have been declared one of the top 100 world's worst invasive alien species by the World Conservation Union, causing issues in places such as Great Britain and other parts of Europe where they do not belong. Time Magazine listed them as one of the top 10 most invasive animals in 2010. Yet while some bird feeders and gardeners in the USA also wage their wars on squirrels, many other people thoroughly enjoy them. They have become regular features of our neighborhoods despite their rarity a century ago. 

This black gray squirrel appears to be lactating and so appears to be raising more squirrels. Each litter may contain both black and normal colored gray squirrels. 

     From ground zero at the National Zoo, the black squirrels continue to spread into the surrounding region. Sometimes they endear themselves, other times they are hated, but mostly they are just ignored. They are with us to stay all the same. Hard to believe how it all started, with the 18 black ones released during the Roosevelt administration. I thought it would be interesting to end with a squirrel mating chase led by a female black squirrel literally playing hard to get to test which of her suitors is the most fit:

                         https://www.youtube.com/watch?v=ohwXkVR3BhU

Katniss - Arrowhead - Duck Potato

Katniss - Broad-leaved Arrowhead - Duck Potato

     Broad-leaved Arrowhead (Sagittaria latifolia) is currently in bloom in our wetlands and goes by a variety of names: Duck Potato, Wapato, and Indian Potato for instance. It is also called Katniss, a name now made more famous for its use for the main character in the Hunger Games, Katniss Everdeen. She was indeed named for this once very important food plant. 

Broad-leaved Sagittaria in bloom in Tuckahoe Park, Arlington, VA with its 3 white petals in whorls of 3.

     In fact most of it's names allude to its edible properties, including the tribal terms Wapato and Katniss. The underground tuberous roots are the most prominent food source and were very valuable to Native American Indian people, whether eaten raw or cooked. There are written accounts of indigenous women going into frigid waters in the middle of winter to try and obtain them. The tubers sometimes floated to the surface, but more often had to be worked free with much effort. The arrowhead-shaped (sagittate) leaves that give it its common (Arrowhead) and scientific (Sagittaria) names can also serve as cooked greens, as can the flower stalks prior to blooming. The Genus Sagittaria is named after Sagittarius the Archer which also gave the astrological symbol. It ranges from Canada into South America, and has also naturalized in such places as Hawaii, Australia, and many parts of Europe.
     Here's a short video on this wetland plant:

https://www.youtube.com/watch?v=0eoKDJwGcF8

     Other tribes used it medicinally: the Cherokee used the leaves as an infusion to treat fevers, the Chippewa for indigestion, the Iroquois for treating boils, rheumatism, and as a laxative, and the Potawatomi for wounds and sores. Civil War doctor Francis Porcher's so-called "Confederate Ethnobotany" also mentions edible and medicinal uses to consider during war time.
     Arrowhead is also the host plant (food) for 5 different caterpillar species. The name name Duck Potato refers to its favored status in attracting ducks, something the Potawatomi tribe reported as part of their hunting tradition (though they prefer the seeds over the tuberous roots in most cases). With the popularity of the books and movies, I thought people might want to know a bit more about why the main character, a forager and hunter living a life of subsistence in a poor community, would be named for this once very valuable plant.

Arrowhead in bloom. The male flowers have yellow stamens while the female have bulbous green centers.

Silver-spotted Skippers

Silver-spotted Skipper Butterfly sharing a meal with a European Honeybee on Hoary Mountain Mint.

     I'm now back from my vacation and am ready to continue the Blog. Since there has been conversation among the environmental community regarding how few butterflies there are this year, I thought I would talk about one kind that is having a very good year. Silver-spotted Skipper butterflies (Epargyreus clarus) are very common this year and most others because they can use a variety of both nectar and host plant (caterpillar food) resources. The caterpillars can feed on most kinds of legumes, though Black Locust trees are among their most favored, perhaps because they are so large and common in our area. Male skippers will often stake out a territory around a patch of host plants and fly out to investigate any thing that ventures in. If it's another male they will chase it out; if it's a female, then they will pursue her. Occasionally they challenge a bird or dragonfly and pay the price for it. They often return to the same perch to watch over their chosen territories.

A Silver-spotted Skipper oviposits an egg under the shelter of a Black Locust tree.

     The photo above shows a female that is ovipositing (laying) her eggs on protected areas of Black Locust. She will land and "drum" the leaf surface with her feet, "tasting" it to make sure she has some form of leguminous plant before depositing them. She generally spreads her eggs out and does not lay more than one egg per leaf. 

The folded leaf shelter of a Silver-spotted Skipper caterpillar on its host plant.

     The caterpillars make shelters to hide in by folding a leaf over themselves and holding it together with silk. As they get bigger they make bigger shelters or may even pull several leaves together to conceal themselves. Their leaf hide-aways are very clean and made fresh regularly. They actually fling their frass (droppings) away from their shelters, helping prevent any predators from detecting and finding the larvae. They can sometimes project their frass up to 5 feet away, remarkable when you realize how small the caterpillars themselves are.

The fake eyes of a Silver-spotted Skipper caterpillar threaten you once you open its shelter.

     If you open up their shelter, you may be surprised by what they look like. Like most skipper butterfly caterpillars, they have a constricted "neck" that gives them a fat-headed appearance. But it's their fake eyes that may startle any potential predator. They will sometimes wiggle around and even open and close their mandibles in a threatening manner in the hopes they can frighten the intruder away. They are of course completely harmless, but it is always neat when I lead a walk and reveal what's hiding sometimes in the bushes or patrolling the air.

Queen Anne's Lace

Queen Anne's Lace at the edge of a field.

     Many of the white flowers that are found in abundance in our open fields and road edges at this time are Queen Anne's Lace (Daucus carota ), sometimes called Wild Carrots. Our modern carrots are indeed descendants of a subspecies of this plant.
     This plant is normally a biennial, flowering in its second year before it dies, but it sometimes takes 3-4 years for it to bloom if growing conditions are poor. It often grows to 3 feet tall and starts blooming from the outside of its flower cluster towards the middle, often blooming for a month or longer. Once done, the flower head dries and curls inwards. This resembles a bird's nest and the plants indeed are sometimes called Bird's Nests.

Bird's Nest - the dried seed head of Queen Anne's Lace or Wild Carrot

     Like our modern carrots and so many other members of the parsley/carrot family, they are edible, or at least the  roots are when young and before they get woody, However, some other members of the family also have similar fern-like foliage and white flowers in flat clusters (umbels) but are actually poisonous (such as Poison and Water Hemlocks). There are differences though, and none have the carrot-like odor to their roots. If you do decide to try them, please make sure of your identification and also note that some people get a rash after handling the leaves if they are out in the sun, a common trait when skin is exposed to chemicals found in many members of the carrot family.

     Queen Anne's Lace is not native but has naturalized here from Eurasia. In fact, in many areas it is considered invasive, particularly in open, sunny areas with clay soils. It of course was eaten in its native lands, but was also used as to obtain a cream-colored dye derived from the flowers. It had been cultivated in a variety of root colors originally ("carrot" is derived from a Celtic word for "red" for example). Orange though now is the color we associate with most commercially available ones. This came about, it is believed, due to the 16th century Dutch who bred them this color in honor of the royal House of Orange.
     It's common name supposedly came about from an ancient legend. Queen Anne (either of Great Britain or Denmark depending on the version of the tale) was said to love to make lace. While "tatting" (making lace by hand), she supposedly pricked her finger and a drop of blood fell onto its center. The lace she was making became the white flowers of Queen Anne's Lace, with the reddish/purple sterile central floret most of the plants are adorned with being the spot where her blood droplet fell.

A Queen Anne's Lace flower umbel. If you look closely you can see the dark central floret.

     While this plant is not native and can in some locations even be considered invasive, it is here to stay. It can be beneficial as well. Some people know how attractive it is not just to many pollinators, but also wasps that can prey on insect pests. It is even recommended as a companion plant to certain crops by some farmers. One creature that has benefited is the Black Swallowtail Butterfly. Its caterpillars use many members of the parsley/carrot family for a host plant, including Queen Anne's Lace. So many interesting things to know about this common field plant that is often not even noticed unless it is in bloom.

A late instar Black Swallowtail caterpillar

Bees

A Metallic Sweat Bee and Bumblebee share a meal on a Wingstem flower.

     In honor of National Pollinator Week, it makes sense to honor the best animal pollinators: bees. Most people are aware of how important bees are for pollination of plants, including some 70% of our crops. What they do not often realize is that we have some 450 or so native bee species in our region, most of which are not at all like the introduced European Honeybee. Honeybees were introduced into the USA in Jamestown, Virginia, in 1627. They are of course extremely valuable for the way we conduct our agriculture and to give us honey, but we need to realize that wild plants were doing fine (maybe even better) before these generalist bees arrived. While most people think that all bees are like European honeybees (living in hives with a queen, making honey, and only capable of stinging once), this really is the exception and applies to these introduced bees rather than most of the other 4,000 or so other species we have in North America.

     The vast majority of our bees for example are actually solitary, with a single female bee taking care of her young, collecting nectar and pollen for them all by herself. She is extremely non-aggressive and many are incapable of even having their stingers pierce our skin. Should that happen however, multiple defensive stings are possible. The reason bees do not do so however is that they would prefer to fly away and not defend their nest, for if the solitary mother dies, her nest and eggs are dead anyways. Better to fly away and start over. Honeybees live for the hive, the workers themselves really not even reproducing, so all they care about is defending their nest, even if they lose their lives stinging in the process.

     70% of all bees live underground, usually in burrows they dig and then provision with nectar and pollen for their developing young. While each solitary bee lives by herself and takes on all the work alone, if the habitat is right, many female bees may nest near each other. Good real estate in a nice neighborhood can be hard to find. After collecting enough food and laying eggs, the bee dies and the bee larvae develop on their own until they emerge, often the next year. 

     Another thing many people do not realize is that although bees can visit many different types of flowers to feed on, about one out of every five of our native species are specialists in the type of pollen they need to feed their young. These specialist bees, often needing the pollen of a single family, genus, or even a single species of flower, are called oligolectic bees. If the specific (normally native) flowers are not available, the bees cannot reproduce. This is another reason to include a great diversity of native flowers in our yards and preserve them in our parks. They need the flowers they evolved with or they simply cannot survive.




Hibiscus Bee Ptilothrix bombiformis, digging her burrow

     The one shown above is usually called the Hibiscus Bee, Ptilothrix bombiformis, which needs pollen from plants in the Mallow family (including hibiscus) to reproduce. These I noticed digging their burrows in one of our Natural Resource Conservation Areas, Arlington Forest Park. They do indeed look like a bumble bee (thus the scientific epithet bombiformis meaning "in the form of a bumblebee") but unlike them, they dig solitary burrows in the ground. These are often distinctly turret shaped, helping with identification. Thanks to friend and colleague Sam Droege, one of the best bee guys in the country, for the help in identification.



Ground nesting bees and their holes

     These bees are remarkable in that they not only dig their burrows, but carry water over on their fuzzy bodies to wet the ground enough to help them in their excavation. The dirt they pull out is often formed into little turrets that surround the entrance to their hole. They are living in this park because they have the bare, well-drained ground they need, a water source nearby, and of course the plants in the Mallow family that they love.

Sand Digger Wasp Drama in Our Playgrounds

Sand Digger Wasp Bicyrtes quadrifasciatus flicking sand

     This is about the time of year I start receiving calls regarding wasps nesting in our sand volleyball and tot playgrounds. More often than not, what everyone is asking about are Sand Digger Wasps. These are solitary wasps (one female per hole) but which can aggregate in large colonies when the conditions are right. They prefer open, sunny locations with soft, clean, and often lighter colored sand. That unfortunately is just what we strive for in our sand lots.

Sand Wasp carrying a paralyzed stinkbug into its burrow

     The most common species we encounter locally is Bicyrtes quadrifasciatus, a stinkbug and leaf-footed bug specialist. In other parts of the country, they have species that go after flies. These are then actually beneficial insects. Each female digs her own tunnel (up to a foot deep) and then brings back stinkbugs she has stung and paralyzed. This she takes down her burrow and the paralyzed prey then acts as the living food for her larvae. 

     Though they can look intimidating flying over the sand, they are actually extremely unlikely to sting unless actually grabbed. In fact, most of the ones flying over the sand are actually males who cannot sting at all. In the world of bees, wasps, and ants, only females (of the few species who can sting at all) can sting, because the stinger is actually a modified ovipositor (egg-layer). Males of course do not lay eggs and so therefore cannot have a stinger. 

     Sand Digger Wasps are only are active for a little over a month, but this happens when the sand lots are in great demand for the summer. Every year, complaints come in and we need to educate people about their pollination and stinkbug control benefits.

     Ideally we would just close down the lots for the time they are nesting, but that is not practical. We are experimenting with various methods to deal with or discourage them. Unfortunately making the area more shady and changing the type of sand is not very well received by the public either.   

     Pesticides are also of course out of the question (more dangerous to kids/public than the critters themselves), as is covering the area up or flooding them (sand drains too well anyways). We are also tilling and sifting the areas they use once the season is over, since they show nest site fidelity (nest in the same area they were born). This hopefully means less of them the following year. We have many other locations for them and they are beneficial, but we need to have them not take up residence in the sand playgrounds.

Sand Wasp pupa next to its cocoon

Sand Wasp cocoons with paralyzed stinkbug prey

     I suspect that Sand Digger Wasps are actually increasing in numbers not only because we have increased what once was an uncommon habitat (sunny sand lots with no plants growing), but because we have so many stinkbugs. I think they are benefiting because they are now preying on the invasive exotic Marmorated Stinkbugs that are not only a nuisance in our homes, but cause great agricultural harm. People may have noticed how much of a problem and how numerous these invasives were before, and how much fewer we have now in certain locales. As I have said, sand wasps are very beneficial if we can just get them to do their good work in other locations.
     More on them on the Capital Naturalist YouTube Channel:

https://www.youtube.com/watch?time_continue=69&v=kJ8_d13U3nY

     Another interesting association with them is a neat little Satellite Fly that parasatizes these wasps. These can be seen following the sand wasps around and waiting for them to open up their burrows once they arrive to them. I have not identified the species yet, only that they are Miltogrammine flies. Once they get an opportunity, they lay their eggs on or next to the paralyzed stinkbug. The fly is a kleptoparasite, meaning its maggot steals the food and often kills the wasp larva in the process. The sand wasp goes through all that work to feed the fly. 

Satellite Fly, a Miltogrammine kleptoparasite fly of these wasps

     I'm often amazed at all the drama that goes on in miniature right under our noses. Here we have wasps who use our playgrounds to raise their young. They do this by providing a paralyzed living food source for their babies (perhaps controlling an invasive pest in the process). But waiting in the wings is a fly who steals the food and kills the wasps larvae. All of this drama taking place less than one foot underground where our children play. Its easy to see why people might get upset, but we need to realize this part of a natural cycle. These wasps are providing a valuable benefit in pollination and controlling stinkbug pests as well, and are harmless to us anyways. Please let others know so maybe we can all figure out a way to share the same space, if only for a month during summer.