Creating a wildlife haven one plant at a time

Sunday, August 23, 2015

Got Milkweed?

Then you have an ecosystem.  Usually we think of ecosystems as big areas like a forest, meadow or lake. But a single plant can play an important role in the survival of a single species or several species.

honeybee on butterfly weed (Asclepias tuberosa)

Most gardeners plant milkweed (Asclepias) to support monarch butterflies. The precipitous decline in their population is reason alone to be planting all the milkweed we can in our gardens as milkweed habitats across the country are dwindling quickly. Every year I plant more milkweed in the hopes that monarchs will come. But they don't always show up. Last year, I mourned the absence of these spectacular butterflies as none were seen in our garden during either their spring or fall migration. In previous years we've had up to 12 arrive at the same time, usually in fall when the winds favorably blow our way. Sadly, we haven't had any monarch caterpillars here since spring 2011.

Monarchs visiting in October last year

(For a list of native milkweed species that grow in Georgia here is a field guide)

Monarch butterflies may not be the most abundant insects found on milkweed but they are certainly the most familiar.  There are other insects, who are also dependent on milkweed plants and couldn't survive without it, while some insects simply use milkweed as a major food source.

Eastern Tiger Swallowtails on Asclepias tuberosa

Milkweed blooms provide nectar for an array of pollinators including butterflies [such as the Tiger Swallowtail, Painted Lady, Great Spangled Fritilary, Buckeye, Black Swallowtail, Pipevine Swallowtail, Pearl Crescent, Clouded Sulphur], honeybees, wasps, and bumblebees.

But, did you know that milkweed is also a vital host plant for several other insects?

There is another caterpillar, usually found in late summer, that eats the older leaves of milkweed and unlike the monarch caterpillars who prefer young, vigorously growing shoots, this caterpillar will even eat the leaves that are turning yellow and crispy. The milkweed tussock moth (Euchaetes egle) caterpillars are orange, black and white and are nothing but hair. Just check out those long black lashes!

milkweed tussock moth caterpillars
These tussock moth cats are communal feeders who hang out in groups of 10 or more on the leaves. Plants are often blanketed with more than 50 caterpillars. Should you be alarmed seeing so many caterpillars defoliating your plants? I say no. These caterpillars hatch in late summer and are not really competing with monarch caterpillars in my garden, who would hatch in spring or early summer during their northward migration. Any monarchs visiting our garden during the fall will most likely be one of the super generation monarchs and not be laying eggs at this time.

Milkweed Tussock Moth (Euchaetes egle) caterpillars on butterfly milkweed

If you look closely at the stems and tops of milkweed you will probably find little yellow round things. These are not eggs but milkweed aphids, also known as Oleander aphids (Aphis nerii), which were introduced from the Mediterranean region where Oleander is its native host.

milkweed aphids (Aphis nerii) on butterfly weed

Like other aphids, milkweed aphids, tend to have a negative reputation, mostly because they feed by sucking the phloem of the plant, which can sometimes cause damage when in large numbers. I recently learned that scientists have failed to find any male milkweed aphids and therefore believe all the adult aphids are female. They produce without mating, a process called parthenogenesis, from the Greek meaning "virgin creation". The females don't lay eggs but deposit nymphs that are clones of the adult females. When conditions get too crowded on a single plant some nymphs are created with wings so they can fly off to establish new colonies on other milkweed (host) plants.

milkweed aphids, some with wings

Teeny tiny ants are often seen running around furiously on the foliage and pods of our milkweed. This is because the aphids secrete large amounts of watery honeydew attracting ants to the milkweed.

ants searching for honeydew on milkweed

Like other insects that feed on milkweed, the aphids are toxic to most predators because they ingest the toxic cardiac glycosides from the milkweed plant. Their yellow coloring is a warning to predators not to eat them.

Syrphid fly larvae eating milkweed aphids
But there are several predators and parasites that can tolerate the glycosides and help keep the aphid populations in check. Milkweed aphids are food for lady beetles, especially in their larva stage who devour large numbers of aphids daily.

Syrphid fly (aka Flower Flies or Hover Flies) larvae are insect predators too and crawl all over the milkweed foliage eating dozens of aphids each day. And there are tiny aphid wasps (Trioxys, Diaeretiella, Lysiphlebus and Aphidius) that will lay eggs inside the aphids and when the wasp's larva hatch it feeds on the insides of the aphid. Aphids killed in this way are often referred to as "aphid mummies".

There are two types of Milkweed bugs, Large Milkweed bugs (LMB)  and Small Milkweed bugs (SMB), that are found in large numbers on milkweed. The Large Milkweed Bug (Oncopeltus fasciatus) is the most abundant in our garden with many stages present on the plant at the same time.

Large Milkweed bug with nymphs
Milkweed bugs are a true bug so you can call them "bugs" without being frowned upon by your entomologist friends. These bugs go through a simple metamorphosis (vs. complete metamorphosis of butterflies). They lay eggs in the crevices between the seed pods. Females lay around 30 eggs a day or 2,000 in a lifetime. A lifetime being about one month! Just like caterpillars, the milkweed bug nymphs grow through a series of molts, usually 5 instars which are a week long.

Large Milkweed Bug instar beginning to show markings

These bugs have a long proboscis which they use to pierce the seed pods to feed on the seeds. My experience is that they rarely reach the inner seeds and therefore there are still viable seeds for producing more plants. Keep in mind that milkweed plants also spread through rhizomes and will form healthy colonies.

Large Milkweed Bug piercing milkweed seed pod

LMBs also suck sap from the plant so they too are toxic to predators. The bugs are gregarious and in large numbers intimidating to predators. An inexperienced bird may try to eat them but will soon learn that orange and black are warning colors.

Some adults may also feed on nectar and I do notice them occasionally on blooms using their long proboscis like a butterfly.

Large Milkweed Bug on fennel blooms

So, you may be wondering what role these bright bugs play. Well, back in the day, before humans started destroying milkweed habitats, these insects would help regulate populations of milkweed.

Single-handedly, milkweed plants support a group of insects, who are dependent on this plant. Perhaps not all these insects are desirable to every gardener, but my experience is that mature milkweed plants come back each spring with vigor. Our view on insect-plant relationships is often skewed by a few insect "pests" on a relatively small number of crop plants. My approach in our garden is to let nature do its thing, thus creating the biodiversity in the garden that is essential to make it grow productively and keep the balance between plants and insects healthy. And you can enjoy watching life on your own little milkweed ecosystem.

Sunday, August 16, 2015

Swallowtail Madness

Simply spectacular, swallowtail butterflies have a certain allure. Perhaps it's because they are such large butterflies which naturally demand your attention. Maybe it is their elegant tails that gracefully trail their expansive wings as they gently float by. Or simply that their movements flow so easily and look effortless. Whatever the reason they are here to be noticed.

Count them...5 swallowtails on joe-pye weed
Swallowtails adorn blooms in our garden from spring through autumn but the height of summer is when they are most plentiful. In fact, they are everywhere. They are constantly taking my breath away when I see them, especially en masse. I often look out the window and count twenty or more swallowtails covering the Joe-pye weed plants. Watching them flit and flutter through flowers is like watching a ballet where the whole garden is their stage.

They are often seen gracefully emerging from the woods, which is home to many of the host plants for the swallowtail species found in Georgia. They are in search of high energy nectar and they have come to the right place.

Joe-pye weed, butterfly milkweed, monarda, verbena, ironweed and swamp hibiscus are blooming right now and they are magnets for swallowtails. Earlier in the summer buttonbush and devils walking stick were calling to them (read more on Not All Plants Are Created Equally).

Spicebush Swallowtail on Swamp Hibiscus

Spicebush Swallowtail on Swamp Hibisucs

Eastern Tiger Swallowtails (Papillo glaucus) are one of the most recognizable butterflies. Not surprisingly since it is the state butterfly for 5 states (Delaware, Georgia, North Carolina, South Carolina, Virginia) but also because of their unmistakeably eye-catching yellow wings. But can you identify the male from the female?

The female is the showier of the two with her shimmery blue tones on her hind wings.

Eastern Tiger Swallowtail (female)
The male is unquestionably handsome in his own right. Without the distraction of the striking blue chevrons the tiger stripes that give this butterfly its name really stand out.

But the female is tricky because there is another form. She also comes in black which is a mimic of the Pipevine Swallowtail (Battus philenor). This dark morph is often found in areas where Pipevine Swallowtails are abundant. The pipevine plant contains aristolochic acid, which is toxic to some animals making the pipevine caterpillar and butterfly distasteful and hence a butterfly to mimic.

Eastern Tiger Swallowtail (female, dark morph)

Eastern Tiger Swallowtail (female, yellow)
To make things even more confusing, this female tiger swallowtail was spotted in our garden which looks like a blend of the dark and yellow forms.
Eastern Tiger Swallowtail, female (dark & yellow form combo)

Spicebush swallowtail (Papilio troilus) has been another predominant swallowtail in our garden this year. This woodland loving butterfly is a sensation. The hazy aqua green on the hind wings of the male is incredible.

spicebush swallowtail on butterfly milkweed

The undersides of the wing look very similar to other black swallowtails with two bands of orange spots. The differentiating marking is the third spot which is replaced with a blue dash.

Spicebush Swallowtail (third spot is replaced with blue dash)

Eastern Tiger Swallowtail (dark morph)

Despite the tell-tail signs I still sometimes struggle differentiating the dark swallowtails from one another, especially if I don't have a chance to inspect the underside. Is it a female tiger swallowtail in her dark form, male or female spicebush swallowtail? You give it a try.

The spicebush swallowtail will lay its eggs on Spicebush (Lindera benzoin) or Sassafrass (Sassafras albidum). We have both, and this season is the first time we've seen the caterpillars.

In the early instar stages the caterpillar looks like bird droppings sitting on a leaf. By the third or fourth instar the caterpillars are too big to pass as poop so they curl themselves up in the leaves to protect themselves against insectivorous birds and other predatory insects during the day. At night, the caterpillars emerge from the leaves to feed. Wrens are known to bite through the center of a folded spicebush leaf to eat the caterpillar, but if a predator were to see the caterpillar they would think twice before attacking this snake mimic.

In previous years we have enjoyed watching Black Swallowtails (Papilio polyxenes), Pipevine Swallowtails (Battus philenor) as well as Zebra Swallowtails (Eurytides marcellus) find refuge in our garden. This year those swallowtail species haven't been as common as the Tiger and Spicebush Swallowtails. Some years just seem to be more friendly to a certain specie(s) of butterflies than others.

So as we patiently wait for the monarch butterflies to find their way to our garden during their fall migration we will continue to be mesmerized by the allure of these beauties.

Swallowtail butterflies on butterfly milkweed

Sunday, July 26, 2015

Not All Plants Are Created Equally

Have you noticed how some plants really have it going on? It's pretty evident that not all plants are created equally, especially when it comes to servicing pollinators. Observing the insects flying around our garden they definitely have their favorites. Conversely, not all insects are effective pollinators.

Pollinators on Aralia spinosa
Pollinators on Aralia spinosa

Earlier this summer if you were a pollinator in our garden the Button Bush (Cephalanthus occidentalis) was the place to be.  If you are not familiar with this terrific plant you can read more about it here. In bloom now are two other natives that are all the buzz in our garden, Devil's Walking Stick (Aralia spinosa) and Rattlesnake Master (Eryngium yuccifolium). These two fabulous plants have the misfortune of having unbecoming common names; fortunately, however, pollinators aren't intimidated.

Pollinators on Eryngium yuccifolium
Pollinators on Eryngium yuccifolium

Have you ever taken the time to really observe the blooms in your garden through the seasons. In our garden some blooms are shrouded in pollinators while others are ostensibly barren.  Why are some flowers seemingly more attractive than others?

Spicebush Swallowtail on Devils Walking Stick

Plants have developed a partnership with pollinators to ensure cross-pollination. Blooms have a certain shape, color, smell or bloom time which provide signs to pollinators to stop by and visit. Insects, on the other hand, have a vested interest in visiting flowers; to gather nectar and/or pollen and they have special tools to do so. It is a mutually beneficial relationship. But now this begs the question, what are pollinators looking for in a flower?

Gray hairstreak butterfly on Rattlesnake Master
Gray hairstreak butterfly on rattlesnake mater

Some blooms are only serviced by a specific pollinator such as a moth, beetle, fly or solitary bee. These flowers have a distinguishing feature(s) to attract that pollinator and exclude other would-be pollinators. The pollinator too has a certain characteristic(s) which allows it to reach the nectar and/or pollen. So how do flowers appeal to different kinds of insects?

Scent~Some plants produce a fragrance to lure visitors. Bees, moths, flies beetles and bats all have a good sense of smell. Moths are attracted to blooms that have a strong sweet perfume that advertises to them in the darkness. Flies, ants and beetles on the other hand are attracted to strong unpleasant odors that resemble rotting flesh.

Time of Day~ Plants open their blooms to make themselves available to their most effective pollinator. Flower pollination can take place during the day, evening or night time from insects that are day, diurnal, crepuscular or nocturnal. Moths and bats drop in on flowers that open in the evening and night time hours while bees, wasps, flies, butterflies and hummingbirds are daylight flying.

Color~Bees don't see the color red instead they base their color vision on UV blue, green and yellow.  Flowers trying to attract bees often have UV patterns on their petals to guide the bees onto the flower landing platform and then into the flower. This is why you will sometimes see bees on red blooms. Butterflies have good vision and visit brightly colored blooms. Hummingbirds are particularly attracted to red and other vibrant colors while moths and bats prefer blooms that are pale in color which are visible on a moonlit night.

Shape~Flower pollination is aided by the shape of the bloom. Open, bowl shaped flowers are especially used by honeybees, bumblebees and some solitary bees that run around the inside of the flower in a circle to collect pollen. Flat, open flowers like members of the Asteraceae family cater to different types of insects including butterflies, bees and beetles. Tubular flowers are especially attractive to hummingbirds and long tongued insects that can reach deep into the back of the flower for the nectar. Bunched flowers such as members of the carrot family (Apiaceae) are attractive to butterflies, bees, wasps and hoverflies.

On the flipside, flowers exploit insects to achieve pollination and ultimately their survival. What characteristics make certain insects more effective pollinators to particular plants or plant families?

Butterflies and Moths (Lepidoptera)~ ingest nectar through their long, very thin proboscis. They take nectar from small tubular flowers and flowers with small tubular florets grouped together in larger inflorescences. It should be noted that some moths don't have mouths and therefore don't eat as adults. Most people are familiar with diurnal moths which are members of the Sphingidae family commonly known as hawk moths, sphinx moths or hornworm moths.

Scape moth (Ctenucha fulvicollis)

Flies (Diptera) are pollinators too! Hoverflies (Syrphidae) and Bee Flies (Bombylius) are two flies that frequently visit flowers. Hoverflies mimic bees or wasps but do not sting or bite. Syrphid flies tend to visit small, flat flowers which present nectar openly. They are flower specialists consuming nectar and pollen. Bee flies mimic bumblebees and have a long proboscis (like Lepidoptera) which is used to drink nectar. Unlike bees they hover in front of flowers.

Syrphid fly

Beetles (Coleoptera) are the biggest group of pollinators by sheer numbers although they are not always the most effective pollinators. The long-horned beetle and flower beetles are two species of beetles that are often found on flowers. Beetles are especially important to plants such as magnolias, sweet shrubs and spicebush. Lady beetles are often seen on flowers but they are mainly going after other insects such as aphids.

Trigonopeltastes delta flower beetle

Bees and Wasps (Hymenoptera) are both seen at flowers. Bees however, are very dependent on flowers to provide both pollen and nectar for their larvae. Wasps, on the other hand, provide spiders and other insects to their larvae and only feed on nectar as adults. Bees have tongues which they use to collect nectar and store in an internal chamber (honey stomach) and when they return to their nesting site they regurgitate the nectar.The length of their tongue determines which shape and size flower they visit. Some species of bees such as leafcutter bees and mason bees collect pollen on a hairy area under their abdomen (pollen brush). Mason bees are excellent pollinators of fruit trees and bushes. Like bees, most wasps are solitary and live in specialized habitats. They have short tongues and are attracted to flowers with sweet liquids (think rotting fruit or jam). This is why you see them immersing their head deep into blooms.

So, not all plants are equal. Each plant and pollinator has a specific survival strategy. Is it better to be a generalist or a specialist? Being a specialists can be problematic if the plant or insect that are codependent disappear from the habitat putting the species in jeopardy. Likewise, as a generalist the risk is that cross-pollination doesn't occur because the insect flies off to visit a different type of flower. There is an amazing interdependence between insects and flowers. Both the Rattlesnake Master and Devil's Walking stick get gold medals when it comes to attracting an array of insects. However, there is no one size fits all plant and this is why it is essential to offer a variety of florae that will appeal to a multiplicity of  pollinators and protect biodiversity so that all these creatures can continue to play a role in the great web of life in the garden.

Monday, July 20, 2015

Gardening for the Marvels of the Night

When planning your garden have you ever considered plants specifically for moths? Butterflies get a lot of attention in gardening circles. The peril of the monarch butterfly has been in the news frequently and brought the subject to the forefront. Butterflies are beautiful pollinators and adding nectar and host plants to attract them is easy to do. For butterfly enthusiasts, there are endless resources including books, classes, articles and blog posts on how to attract butterflies. There are butterfly gardens at nature centers, botanical gardens, parks, zoos, schools and many other public facilities encouraging the public to create similar environments at their homes. Yes, I love butterflies but they are only one family in the insect order Lepidoptera. The other 96% are MOTHS.

Promethea Moth (Callosamia promethea)
Often ignored or completely neglected, moths are hugely important in the garden. Not only are they critical pollinators but they are also important in a balanced ecosystem providing food for lots of baby birds. This week is National Moth week (July 18-26) dedicated to the awareness of this magnificent member of the Lepidoptera family. I encourage you to take some time to observe the diversity of moths in your region, learn about their life cycle and study up on the habitat needs of moths so that you can provide for them in your garden.

Virginia creeper sphinx moth (Darapsa myron)

There are three times as many moths species as butterflies and they are extremely diverse and interesting. Since most moths are nocturnal they are rarely abundent unless we see them by artificial light or conspicuously resting during daylight hours. This week try leaving a porch light on and see how many moths you attract after dark. You may be surprised who shows up. We left the lights on at our front door recently and got some tremendous results.

In one evening we attracted some impressive visitors. This is what caught my eye from inside the house and invited me to open the door to see who arrived. Two Luna moths, one at our front window and the other hanging from the door frame were my first observations.
Luna Moth

Luna moths are probably the most endearing moths; I suspect since they are so large and look very much like a butterfly.  They are also strongly attracted to UV wavelengths and therefore are often seen at house and street lights. There is some concern that light from man-made sources deters lunas from mating and therefore has a negative impact on their populations in urban areas. 

Luna Moth (Actias luna)

Their silk moth family name Saturniidae is based on the eyespots that contain concentric rings reminiscent of the planet Saturn. Members of this family are large and some of the showiest moths around with striking colors and shapes. Moths included in this group are the Cecropia, Polyphemus, Promethea, Luna, Io and Imperial moths.

The regal moth (Citheronia regalis) is another very large moths and was also at our front doorway. It has a wing span of 5.5 to 9.5 cm. and the caterpillar (larvae stage) is equally as large, growing to almost 14 cm. They host on a variety of trees including walnut, hickory, pecan, persimmon, sweetgum and sumac.

Regal Moth (Citheronia regalis)
Their gray and orange stripe pattern on the wings is stunning and I was taken by its adorable fuzzy striped head. I really wanted to reach out and give it a little tickle.

Another intriguing moth, found clutching to the window, is this Imperial Moth (Eacles imperialis). This moth has just one brood a year and hosts on several conifer and deciduous trees including pine, oak, box elder, maples, sweetgum, honeylocust, red cedar, sycamore, basswood, bald cypress and sassafras. Adults emerge before sunrise and mate after midnight the following day. The female then lays her eggs at dusk and the caterpillars hatch in about two weeks. Pupation takes place underground overwinter.

Imperial Moth (Eacles imperialis)

The forest dwelling Rosy Maple Moth (Dryocampa rubicunda) is one of the smallest of the silkworm moths with a wing span of just 2 inches. The caterpillar often called green-striped mapleworm, eats the foliage of maple and oak trees. Young caterpillars feed in groups and then become solitary as they mature. They are fierce feeders in their larvae stage sometimes defoliated trees. As adults however, they do not eat at all, relying on their fat storage to survive. Three generations are produced in the South and the last generation will overwinter in its pupa stage underground emerging the following spring.

Rosy maple moth (Dryocampa rubicunda)
The unmistakeable Giant Leopard Moth is another example of the gorgeousness of moths. Just look at those metallic accents. You can read more about this species on my post profiling this moth here.

Giant Leopard Moth (Hypercompe scribonia)

Moths in their adult form are essential pollinators. They are the night shift if you will, taking over pollination services from butterflies who fly during daylight hours. It is easy to create a habitat that supports moths.Here are a few essential elements.

Plant a variety of flowers
Most moths in their adult form need nectar for energy. Certain blooms have more available nectar so by choosing these plants for your garden you create a better feeding station for moths. Native plants are more nectar rich than hybrids or cultivars. In general moths are attracted to cluster blooms and flat open flowers that provide for easy landing preferably in white or dull colors. Double blooms have little to no nectar availability. Blooms that service moths typically open in late afternoon to early evening specifically for these nocturnal flyers many of which are highly fragrant. Some plants are solely dependent on moths for pollination and thus their survival. The yucca moth for example is the sole pollinator for the yucca plant. It is a good idea to have blooms available from early spring through late fall. Datura, Four o'clock, flowering tobacco, honeysuckle, morning glory, evening primrose, and Jasmine are a few examples.

You need host plants
Certain plants provide the necessary food for the caterpillars. Some species will forage on a wide variety of plants while others are restricted to a few plants and some only to one type of plant. Many trees are hosts for moths such as oaks, maples, hickory, sweetgum, cherry, pine, sassafrass, persimmon and willow. Moths in their larvae form can be as spectacular as adults. Take a look at a few we see in our garden.

Saddleback caterpillar (Acharia stimulea)

white flannel moth (Norape ovina)

American Dagger Moth (Acronicta americana)
Wolly bear (Pyrrharctia isabella)
Virginia Tiger Moth (Spilosoma virginica)

Stop being so tidy!
As a general rule you can't keep an immaculate garden and expect to support wildlife. So now you have an excuse to be a lazy gardener. Moths in the adult and larvae stage need leaf litter, old stems, logs and plant debris to hide from predators. Don't cut back your expired plants until spring. Many moths overwinter in the ground in their pupa stage and need undisturbed places to do so. 

Luna Moth resting in brush and leaf litter during the day

Dare to go organic
Herbicides and pesticides are harmful to moths in all stages. Organic gardening is beneficial to all wildlife plus eliminating these chemicals will also increase the number of beneficial insects in your garden.

This week, challenge your preconceptions about moths and get to know these marvelous insects. You may even be inspired to create a welcoming habitat in your garden by including some nectar and hosts plants specifically for moths.