Wednesday, June 22, 2016

Butterflies and Moths as Pollinators

A Sulphur and Buckeye butterflies nectar on a Stokes Aster.

     Although often considered great pollinators, both butterflies and moths really are not the best at moving pollen from one flower to the next. Unlike their pollinating colleagues, the bees, they just are not built to be good pollinators (and since many moths do not even feed as adults, many don't pollinate flowers at all). They lack enough "hair" to effectively carry pollen. Their long legs and proboscis often keep them from making much contact with pollen anyways and they thus don't carry much to other plants.  

While not the best pollinators, this Eastern Tiger Swallowtail has certainly picked up pollen to transfer by burying itself in this daylily.

     But they do pollinate some plants. About 8% of the world's plants rely on Lepidoptera (butterflies and moths) as their primary pollinators. The pollination of plants by butterflies and moths is referred to as psychophily. Some butterflies and moths do also have the advantage of flying longer distances than other pollinators such as bees and transferring pollen longer distances with them. Some long-tongued moths (such as sphinx moths) are especially adept at pollination of night blooming flowers, and some plants have evolved to attract them as their primary pollinators. This was famously theorized by Darwin in 1862 when he predicted that an extremely long Madagascar orchid must have a pollinator with a proboscis 11 inches long in order to reach the nectaries, and he was right. Moth pollinated flowers are often tubular, white (what other color would show up at night?), and fragrant. 
     Butterfly pollinated plants are usually white, yellow or blue. They tend to have flat topped, open blooms to provide a good landing platform and easier access. Composite flowers provide multiple feeding opportunities per visit and are often favored as well. There tend to be less butterfly specific plants than moth specific plants.
     Some plants hedge their bets attracting pollinators both day and night. Others appear to be more fragrant at night to attract nocturnal pollinators. A visit to a blooming buttonbush or common milkweed patch at night can reveal all sorts of visitors as proof.

Multiple Banded Tussock Moths feast on the Common Milkweed patch at my house.
    But there are also daytime flying moths, some of which are colorful. And of course there are many butterflies (Virginia has about 168 and Maryland has about 151 different species) who also visit flowers. Much like other pollinators, they are capable of learning which flowers to visit and which give them the best rewards. This benefits the butterfly/moth because it doesn't waste time finding flowers with less rewards unless it has to, and because it doesn't have to figure out how to access the nectar every time. It benefits the flowers of course because the pollen from the same species of flower ends up in another of the same species. Less is wasted than if the pollinator visited flowers randomly. Thus pollinators have evolved to benefit themselves and the plants they choose to visit.

The Ailanthus Webworm Moth, a daytime flying moth, favors goldenrods to nectar at.

     You can also make your yards and gardens more attractive to them (and to other pollinators) by doing just a few simple things, some butterfly/pollinator gardening basics:
  •Avoid using pesticides and/or herbicides.
  •Plant for continuous blooms throughout the seasons.
  •Use mass plantings.
  •Include host plants.
  •Provide basking sites.
  •Consider puddling areas.
  •Try to locate your garden in the sunniest location you have.
  •Consider flower color and shape.
  •Avoid double-flowered or other cultivars.
  •Go Native! Use the native plants they evolved with, not just to feed the adults, but even more so the caterpillars which often are very specific about the host plant they will feed on. 
     So enjoy these colorful visitors to your gardens and yards. They may not be the best pollinators in the world, but they play their part. Even more so, their caterpillars form the largest proportion of food for our migratory birds, while the adult moths form the main dish for our bats. You might even recognize the same ones who visit from such things as damaged wings, knowing they learned that your yard had the best rewards. They then reward the plants in your yard, as well as the people who watch them. 

This Great Spangled Fritillary got to know me pretty well in my yard. licking salt off my hand.

Monday, June 20, 2016

National Pollinator Week

A bumblebee, sweat bee, and orange-spotted mint moth all feeding on a native Green-headed Coneflower. 

     Happy National Pollinator Week! To help celebrate, I hope to post about a pollinator each day for us to learn about and appreciate. But first a bit on pollinators in general. There are over 200,000 species of pollinators worldwide. These include such animals as bees, wasps, butterflies, moths, flies, beetles, and hummingbirds. We owe them much, as it is often said that one out of every three bites of food we enjoy is due to the direct actions of an animal pollinator. In fact, three quarters of all plants regardless depend on animal pollinators in order to reproduce. 
     When thinking about planting things to benefit our pollinators who benefit us so often, it is most important to consider the use of native plants. Some studies show that native plants are four or more times more attractive to native pollinators than exotic plants. This of course makes perfect sense since these plants and animals evolved together, sometimes to the point that one cannot exist with out the other. 
     So the most important consideration is to plant plants that are locally native. These plants are not only adapted to grow in this type of habitat, but are what the pollinators have been using for thousands of years. It is always best to use straight wild species, rather than cultivars or nativars which have been selected for certain traits. When we plant a flower that has been bred to appeal to us through a novel color or look, it may not have the same appeal to the pollinator its parent plants originally evolved with. What we think might be more attractive often isn't the case with the pollinator, some of which see flowers through different spectrums or look for certain traits in them. This is especially true of plants bred to have double flowers or blooms with extra large petals, since they often sacrifice nectar/pollen for the extra showy flowers.
     Finally something to consider are the multiple uses you get with native plants. Many exotic plants may have a pretty flower that may (or may not) provide nectar for a short time each year while blooming, but it otherwise provides little habitat for pollinators or other native wildlife. Take the Chinese Aster (Callistephus) for example. It is a pretty flower, comes in many color forms and is widely planted (and escaped and naturalized into some areas). The blooms on some varieties provide some nectar and pollen to a few pollinators for a short bloom time each year. But only two species of caterpillars have been recorded as feeding on it. It is for the most part and for most of its plant life a barren habitat for wildlife, taking the place of what might have been a much more beneficial native plant.

A Pearl crescent Butterfly feeds on a native Orange Coneflower, but only because its caterpillar had a native aster to feed on, the only thing the caterpillars can eat.

     Contrast that with one of  our many colorful and attractive native aster species, many adapted to a variety of growing conditions. Now you have flowers that not only provide attractive flowers for the garden and a similar look, but also serve a habitat function. In addition to pollinators visiting them, most also supply seeds for birds such as finches and sparrows. But 109 different caterpillar species have also been documented feeding on them. These in turn feed the vast majority of our nesting native birds (97% of terrestrial birds feed on insects, particularly during the nesting season, most of which are caterpillars) and most of the 17 bat species found in our region (all of which are insectivores and many of which prefer moths over other insects). 
     So you can see how something as simple as choosing a native plant species can not only serve to provide for pollinators, but then serve other habitat functions as well. So this National Pollinator Week, enjoy the pollinators in our gardens, farms, and parks. If you're able to, include locally native plants in your gardens. This way you too can help the pollinators who are always helping us. 

Three Tiger Swallowtail Butterflies, Virginia's state insect, feed on a native Buttonbush. Nineteen species of caterpillars feed on the plant itself and many birds eat the nutlets.  

Friday, June 10, 2016

Ichneumon Wasp Trogus pennator

The parasitoid ichneumon wasp Trogus pennator.

     The natural world is intricately connected and isn't always what some people might consider nice in how it works. Take for example the colorful Ichneumon Wasp pictured above, Trogus pennator. It is about an inch long and the the iridescence of its wings can make the colors look variable. This pretty wasp is harmless to us (its coloration is thought to perhaps mimic stinging wasps to protect them from predators), but certain caterpillars need to take care when she's around.

Trogus pennator wasp searching for Tiger Swallowtail caterpillars ona Tuliptree leaf. Notice how the iridescence can alter the perceived color of the wings.

     All 6 members of the Genus Trogus in North America are parasitoids of swallowtail butterfly caterpillars. "Trogus" comes from the Greek for "gnawing." "Penna" is Greek for "feather wing" and the wings are indeed attractive. Ichneumon wasps like Trogus in the subfamily Ichneumoninae all need caterpillars as hosts for their young. Adult females find certain caterpillars and inject a single egg into them. The caterpillar continues to feed and grow as though healthy, but that is an illusion. It is walking dead, doomed to die when it pupates with the Ichneumon emerging from its zombie host. That is why they are called parasitoids rather than parasites. Both terms imply an organism feeding and harming the host, but parasitoids always kill the host, where parasites do not always result in death. 
     Trogus pennator is no different. Adults may feed on nectar or honeydew, but the females need caterpillars in order to reproduce. They hunt for Swallowtail Butterfly caterpillars (Family Papilionidae), apparently being able to use any of our native ones as hosts. These wasps seem to show a distinct preference for searching on the host plants of swallowtail caterpillars, somehow being able to identify them visually or perhaps even chemically. They always seem to hunt in such swallowtail host plants as pawpaw (Zebra Swallowtail host plants), tuliptree (as in the photos where Tiger Swallowtail caterpillars would be feeding), cherry (Tiger Swallowtail hosts), sassafras (Spicebush Swallowtail hosts), spicebush (Spicebush Swallowtail hosts), snakeroot (our native Pipevine Swallowtail host), pipevines (where planted since not a locally native plant for Pipevine Swallowtails), and members of the carrot family (Black Swallowtail host plants). They also then seem to target leaves with damage, like what a feeding caterpillar would leave.
     When a swallowtail caterpillar is found, she injects a single egg and the zombie-like life of the caterpillar begins. The wasp larva feeds inside, but does not destroy the vital organs, allowing the caterpillar to continue to grow. Eventually the swallowtail caterpillar forms its chrysalis. But what emerges is the adult wasp rather than a swallowtail butterfly. This endoparasitoid exits through a small circular hole in the side of the chrysalis, leaving just an empty skin behind. The wasp then looks for a mate and starts the life cycle all over again.  
     While they may kill swallowtails, they do not eradicate them. Keep in mind that the only things the larvae of these wasps can feed on are swallowtails. It would make poor evolutionary sense to kill off all of the only host you can survive on. So they do kill some, but not all, as they have evolved together to coexist. That involves behavioral adaptations by the swallowtails as well such as choosing low places to lay eggs which are less attractive for wasps to search or feeding at night such as the Zebra Swallowtail caterpillars do when the wasps (and birds) would be sleeping. 

An empty swallowtail butterfly chrysalis. Notice the circular exit hole where the wasp emerged after consuming the host.

     So this may seem cruel, but these are just all parts of the nature puzzle. People who know me know that I like to use a puzzle analogy for the natural world. It's a puzzle because certain pieces fit together (such as the swallowtails needing certain plant caterpillar hosts and Trogus needing swallowtail caterpillars). As a naturalist, I try and solve as much of the puzzle as I can, knowing this will be life long learning. But as any puzzle maker knows, you need all the pieces or you can't really complete the puzzle. As the great naturalist Aldo Leopold is credited with saying "the first rule of intelligent tinkering is not to lose the pieces." Unfortunately we are losing pieces through extinction and loss of habitat all the time. 
     We also know that you can't take a piece from another nature puzzle where it fit perfectly well and stick it into another puzzle. That causes other pieces to no longer fit well. This is what happens when we introduce invasive exotic species into new habitats. I love trying to learn how the pieces fit together, even if they are sometimes a bit gruesome in the way they do so. The life cycle of this colorful wasp is just one example of the fascinating puzzle of a natural world we all live in. 

Wednesday, June 8, 2016

Golden-Backed Snipe Flies

A female Golden-backed Snipe Fly

     Flies are rarely considered beautiful and are mostly looked upon with disdain, but there are thousands of kinds of flies, some with fascinating life histories and others which are quite attractive. Take the Golden-Backed Snipe Fly (Chrysopilus thoracicus) for instance. This is indeed a handsome fly. Found during late spring through early summer, these flies are quite noticeable due to their bright coloration.
     All of North America's 32 species of flies in the Genus Chrysopilus are bright colored. The Genus name actually translates to "golden-hair" and this is a distinctive feature. The species name thoracicus is said to refer to the slight striping along the thorax. Both of these are thought to help mimic a bee or wasp, which tend to be avoided by many predators since they may be able to sting. This may offer some protection to these flies.

A female Golden-backed Snipe Fly pretending to be a bee.

     Golden-backed Snipe Flies are harmless however. They inhabit deciduous woods, often either sitting facing downwards on a tree trunk or sitting on low foliage. Since other species of Snipe Flies (Family Rhagionidae) are predatory as adults (some even bite), Golden-backed Snipe Flies are believed by some to prey on other smaller insects as well. But that has not been proven. Some other experts think the flies may not even feed as adults. 
     As in most flies, the females are larger and more rotund than the males. This is so they can carry more eggs. Male Golden-Backed Snipe Flies are thinner and have what are referred to as holoptic eyes. Their eyes seem to almost meet in the middle top part of their heads, the better to see females with. The male hooks himself to the rear end of the female, facing away from each other. They can stay in this position for hours. If they are disturbed, the female will often carry the male in this position a short distance before landing again, never breaking contact. 
     The life cycle of Golden-Backed Snipe Flies is not well known. Since other snipe fly larvae are predatory and can live in moist wood, perhaps that's the case with these. But that discovery has yet to be made. It just goes to prove how little we really know about the natural world and how much more we still have to discover, even about common and colorful creatures such as these.

A male Golden-backed Snipe Fly, note how the large eyes almost touch and how thin it is compared to the more robust female in the first photo.

Friday, June 3, 2016

Serviceberries - Juneberries

Ripe Juneberries ready for picking!

     Shrubs in the genus Amelanchier go by a variety of names, each with their own stories and lore: Juneberries, Shadbush, Shadblow, Serviceberry, Sarviceberry, Saskatoon, and Sugarplums among so many others. I won't go into details about all these names, but have a chosen a few to tickle your appetites to learn about these great woody plants.

A cupful of Juneberries from the Dwarf Serviceberry in my yard. 

     Let's start with the term Juneberry, given to the shrubs because many species have their fruits (a pome in botanical terms) ripening in early June. Most species have not only edible, but delectable, fruits, whether eaten fresh, dried, in pies, or as jam. These are a wonderful treat for wild food foragers like myself (if you can beat the birds and other animals to them anyways). The native peoples often used them as a main ingredient in pemmican traveling cakes, among the many other dishes they were also used in. Francis Porcher's so-called "Confederate Ethnobotany" published during the Civil War provided instructions about how to use the fruits to produce an alcoholic drink also. As if that wasn't enough, the shrubs act as host plants themselves to provide food for 124 different documented caterpillar species, which of course provide even more food for birds (96% of terrestrial birds feed on insects with caterpillars making up the most sought after), our 17 species of bats, and other wildlife. This is indeed a bountiful food source anyway you consider it.
               Here's a short video which shows the berries and discusses them:  

     But these shrubs also provided so many other uses. Some Native American Indian tribes used them for arrow shafts, others for baskets, and even more to construct digging tools. Parts of the plants had numerous medicinal uses, including as eye or ear medicine, for stomach ailments, to treat colds, and as a general medicinal tea. It would take a whole other Blog article to relate the various ways different tribes used these native shrubs. 

Dwarf Serviceberry in bloom in my yard.

     The names Shadbush or Shadblow refers to the tendency for the shrubs to flower in April, often during the spawning season for fish such as shad. They supposedly served as a signal for people that the fish were running in the rivers and to go fishing.
     There are numerous stories attached to why these woody plants are called either Serviceberry or Sarvisberry. One relates to the plants' similarities to the fruit of European plants in the genus Sorbus. Another relates that the shrubs would flower just as the roads became passable again to allow for the preachers who would travel to be able to arrive to once again provide religious services after the winter season had passed. Yet another relates that blooms signaled that the ground had thawed enough to allow for burial services.
Serviceberry blooms

     Regardless of what name is used, these are truly remarkable and beneficial shrubs. Luckily these adaptable plants are used quite a bit in landscaping and are beautiful when in bloom. We can then enjoy them as edible landscaping in June too. But we really can enjoy these plants any time of year, as can all the wildlife that depends on them.