Ramble Report August 4 2016

Today's Ramble was lead by Dale Hoyt.

Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don.)

Today's post was written by Dale Hoyt.

Announcements:

The State Botanical Garden of Georgia has a new weather station that is internet connected. You can get up-to-the-minute weather at the Garden and a forecast. Visit the website at: https://athensclarke.weatherstem.com/sbg

When at the above website click on the "Handout" menu item to discover the many other features available: Twitter, Facebook, automated phone weather information, etc. It's a wealth of weather information you can explore!

Our fellow Rambler, Bob Ambrose, has published his new book of poetry: Journey to Embarkation, poems written mostly before he began writing about nature. Bob says that his book will be available at Avid Books beginning Friday, August 5. He will also have a few copies that you can purchase from him at our next Ramble. (The book is also available online from two sources: Amazon and Parson's Porch & Book Publishing Co.)

Number of attendees: 24

Today's reading:

Queen Anne's Lace

"A pest to farmers, a joy to the flower-lover, and a welcome signal for refreshment to hosts of flies, beetles, bees, and wasps, especially to the paper-nest builders, the sprangly wild carrot lifts its fringy foliage and exquisite lacy blossoms above the dry soil of three continents. From Europe it has come to spread its delicate wheels over our summer landscape, until whole fields are whitened by them east of the Mississippi. Having proved fittest in the struggle for survival in the fiercer competition of plants in the over-cultivated Old World, it takes its course of empire westward year by year, finding most favorable conditions for colonizing in our vast, uncultivated area; and the less aggressive, native occupants of our soil are only too readily crowded out. Would that the advocates of unrestricted immigration of foreign peasants studied the parallel examples among floral invaders! "

From: Wild Flowers Worth Knowing, Adapted by Asa Don Dickinson from Nature's Garden by Neltje Blanchan 1917

After the reading Mary Ann mentioned that Queen Anne's Lace was the first flower her young children recognized. The placed the cut flowers in water with food coloring and watched as the flowers changed colors.

Today's route: Our focus today was on insects that visit flowers, so we followed the same route as two weeks ago –through the Spanish America, Mediterranean and Middle East sections, then through the Herb and Physic and Heritage Gardens, finally venturing into the Flower Garden to check for insects around the lantanas and returning back to the Conservatory and Donderos' for refreshments and conversation.

Warm-blooded Bumblebees:

Bumblebee bites through the base of a Salvia flower to "steal" some nectar.

When we arrived at a bed of Salvia there were a number of Bumblebees flying from flower to flower, but no other bee activity – no honeybees or small solitary bees. The air temperature was in the low 70s, and a bee can't fly until it's body temperature is at least 86. Insects are considered to be "cold blooded," taking on the temperature of their surroundings. It should have been impossible for the bees to fly on such a cool morning with little or no direct sunlight to bask in. Yet fly they did. The solution to this puzzle lies in their circulatory system. It enables them to be partially "warm-blooded." The explanation is rather lengthy so I've made it a separate blog post that you can read here, if you're curious. 

Nectar robbing

The Bumblebees visiting the Salvia flowers were not just nectaring, they were nectar robbing. Instead of entering the flower at the top, where the opening is, they were going to the base of the corolla and biting an opening to get at the nectar. Why would a bee do such a thing? It seems like a violation of nature, doesn't it? The Salvia corolla is very long and only a hummingbird or a very long-tongued bee could reach the base of the corolla from the conventional entrance. So what's a hungry bee to do? Go to the back door and break in, apparently. (Some of the Ramblers acted like they wanted to discipline those nasty bees, but the patterns of nature, like the mutualistic nature of the pollinator-flower relationship, is not a law like gravity. In human society there are people who steal things and we sanction them. But nature has no moral codes and we need to avoid projecting our human values onto it. End of rant.)

Green anole, Carolina anole, American chameleon:

All these common names have been applied to the small, green lizard (Anolis carolinensis) we saw today. It is not a true chameleon; real chameleons are lizards living in Africa and Madagascar and are much more adept at changing their color than our little anole. The anole also does not change color to match its background. It's color change is limited to green and brown. Mature males have an extensible throat fan, called a dewlap, that is colored pink or red. It is usually displayed when another anole is entering the owner's territory and is thought to function as both a territorial and sexual signal. The dewlap display is usually accompanied by a series of jerky pushups, it which the front of the body is elevated and lowered several times in rapid succession. If the encroaching lizard is a male it may flee or engage in a fight that the territory owner usually wins, if they are evenly matched.

The pronunciation of "anole"

I have heard many variations in the pronunciation of "anole": 1) "uh-knoll," 2) "an-ol," 3) "uh-knoll-ee," "an-ol-ee." In fact, five years ago I asked an anole expert for the proper pronunciation. You can read the replies, mixed in with the origins of the word, here and here.

How Green anoles change color

The skin of anoles contains four layers of pigment cells. The lowest layer consists of cells that contain the dark pigment melanin. (Melanin is the pigment that produces a tan in human skin.) These cells, called melanocytes or melanophores, have numerous long processes that reach through the pigment cell layers above them. The melanin granules in the melanocyte can either be huddled together in the cell body below the top layers of pigment cells or dispersed into the long branches above the other pigment cells. In the first case the color of the anole is green; in the second, brown, the melanin pigment granules effectively covering the underlying pigment cells. The change in color is controlled by hormones, especially adrenalin and MSH (Melanocyte Stimulating Hormone). When excited or stressed the anole produces adrenalin and the melanocytes retrieve all their melanin, revealing the underlying green color. MSH has the opposite effect, causing the melanocytes to disperse their melanin, covering up the green color.

Why do Green anoles change color?

The conditions that cause Green anoles to change from green to brown and vice versa are complicated and not well understood. This post provides a summary of some of the studies that suggest how different social and ecological factors affect the color of Green anoles.

Butterflies

We saw several kinds of butterflies today: Eastern tiger swallowtail, Gulf Fritillary, Long-tailed skipper, Silver-spotted skipper, Ocola skipper and a Hairstreak that escaped before it could be photographed or identified.

Tiger swallowtail

Female Tiger swallowtail; note the blue coloration in the black border of the hind wings.

Male tiger swallowtail; note the absence of blue on the black border of the hing wings;
also note the wedge-shaped piece missing from the right hind wing -
this butterfly escaped an attack by a bird

Female tiger swallowtail; melanic form that mimics the distasteful Pipevine swallowtail
Note the heavy blue marking on the upper hind wing characteristic of females

The Tiger swallowtail is easily recognized: it is large, with yellow and black stripes. We saw several two weeks ago (July 21) and they were just as abundant today. In that weeks Ramble Report I discussed the same things we looked at today: how to tell male Tiger swallowtails from females, the two different forms of female Tiger swallowtails (dark vs. yellow with black stripes), and why the dark female form is commoner in the South and rare or non-existent in the North. You can read that section again if you want a review by clicking here and scrolling down.

Gulf Fritillary and Long-tailed skipper

Gulf fritillary; underside of wings with silver spangles

Long-tailed skipper; an immigrant from Florida

It may seem strange to discuss two such different butterflies together, but the Gulf fritillary and the Long-tailed skipper have something in common. They are both temporary immigrants to our area. Both are resident (i.e., can be found year-round) in south Florida and Texas. As the weather warms in the spring they spread northward, the Gulf fritillary reaching our area at the end of May or early June, just after their host plant, Passion vine, has begun to emerge. The Long-tailed skipper is a little later arriving in Athens, appearing usually in late July or early August. Its hosts are plants in the bean family. Neither of these is a permanent resident in our area because all stages of their life cycle (egg, larva, pupa or adult) cannot survive our winters.

Passion vine fruit; vine has reddish stems with 3-pointed leaves

The Gulf fritillary was seen flying near a Passion vine so we should look carefully for caterpillars on our next visit.

Migration or dispersal?

The Gulf fritillary and the Long-tailed skipper raise an interesting question: Are they migrating, like the Monarch does? In the case of the Monarch butterfly most of the population east of the Rockies in Canada and the United States ceases reproduction in the fall and flies several thousand miles to a few locations in the mountains of Mexico. There they overwinter until the spring and then they mate and fly back north, laying eggs on freshly emerged milkweed plants as they go. Only a few will reach the southern US, but the eggs they laid on their way will hatch and the caterpillars will feed, develop and become butterflies that will continue the journey north. And so will their offspring. The key features of migration here are 1) physiological change (they cease to lay eggs and accumulate stores of energy in the form of fat), 2) directional movement to a 3) destination and 4) return toward their origin.

But simple dispersal could explain the pattern of arrival more simply. Individuals in a region of mild climate like south Florida fly about looking for suitable plants to lay eggs on. As the season progresses fresh food plants begin to appear in more northern areas. If their flight direction is random some individuals will fly north and be more successful than those that flew south. And the same for their offspring, until the spreading wave of colonists finally arrives at the northern limits of its food plants or its climatic tolerance. Dispersal like this is similar to simple diffusion: if things randomly wander about from a single point of concentration eventually they will uniformly occupy the entire volume. So simple dispersal could account for the appearance of Gulf fritillaries in the northern states during the summer.

In support of this idea I've noticed that, unlike the Monarchs that cease reproduction, the Gulf fritillaries in my yard continue to lay eggs even as the Passion vine is dying in early fall. But the chrysalids produced at that time do not survive the winter and the caterpillars don't have anything to eat. If these butterflies were migrants they should cease reproduction and show signs of flying back south.

Miscellaneous critters

In the Heritage Garden where we looked at the Sorghum patch two weeks ago there were still hordes of wasps and other insects attracted to the honeydew produced by aphids feeding on the Sorghum plants. There were not as many, due to the heavy overcast skies, but still enough to be interesting. 

Spider wasp

Spider hunting wasp

One of the more unusual solitary wasps was a Spider wasp with bright yellow antennae and shiny black wings with browning tips. This wasp specializes on spiders, including wolf spiders, that it paralyzes and carries back to its burrow where it lays an egg on the spider and then seals off the chamber. In the desert southwest of the US larger species in the same family hunt Tarantulas!

Asian multi-colored lady beetle

Asian multi-colored lady beetle; the white blobs are her eggs.

Same beetle as above, viewed from the other side showing the eggs.

In several places we saw Asian multi-colored lady beetles (commonly called Ladybugs). Lady beetles, both adults and larvae, are predators that eat aphids. This particular species is an introduction from Asia, as the name implies. They are suspected to have caused the decline in numbers of our native Lady beetles which are much less common than before the Asian beetle was introduced. Don spotted one female in act of depositing eggs on a piece of plant fiber. This is a dangerous area to lay your eggs with so many ravenous wasps milling about, but they are unlikely to blunder into a few eggs hanging down from the edge of a leaf. It's nice to have Don back with us!

Cicada "shell"

Empty exoskeleton of an Annual cicada; note the strong front legs modified for digging.

Adult cicada like the one that emerged from the exoskeleton above
(photo taken last year)

Now is the time of year when the Annual cicadas are beginning to emerge to sing their droning melodies in the afternoon and early evening. The first sign of their presence is the appearance of the shed exoskeletons of the nymphs that have spent one or more years underground, sucking the sap from tree roots. You can see in Don's photo of the shed the powerful front legs that allowed the nymph to dig its way out of the ground and crawl up a plant stem. The back of the exoskeleton splits open and the adult cicada slowly extricates itself from the old exoskeleton. It takes several hours for the wings to expand and the new exoskeleton to harden; then the cicada can fly off. There are about 10 species of Annual cicadas in Georgia. (Annual cicadas appear every year.) They are not to be confused with the Periodical cicadas that emerge only every 13 or 17 years. The next emergence of 13yr cicadas in Georgia is due in 2024. 

Ailanthus webworm moth (AWM)

Ailanthus webworm moth

This curious looking and colorful moth is commonly seen all summer into fall. It was originally found only in tropical regions, but began to appear when the Ailanthus tree was planted in the US. Ailanthus is native to China and became a popular urban tree because it was very tolerant of pollution. The AWM discovered that it could feed on Ailanthus and has spread over the US where ever Ailanthus trees are available. The caterpillars tie several leaflets together to form a silken web or nest within which they feed. I have never seen an Ailanthus tree in Athens or the Garden, so I'm curious as to where these moths come from.

Orbweaver spider

This tiny spider creates this perfect orb web and decorates it with thicker silk.

Someone with sharp eyes saw this tiny spider with a perfect orb web and a thick, spiral weaving of silk around the space where the spider sits. We don't know what kind of spider it is and we don't know what function of the thicker silk platform, called the stabilimentum, is. The stabilimentum is found in many, but not all, the webs that orbweavers make. Some ideas as to its function are: 1) it makes the web more visible to birds so they won't fly into it; 2) it attracts insects toward the web so they can be captured. Both hypotheses have received some support, but the question is still open.

SUMMARY OF OBSERVED SPECIES:

Common Name	Scientific Name
Canada goose	Branta canadensis
Eastern tiger swallowtail	Papillo glaucus
Tall ironweed	Vernonia altissima
Salvia	Salvia sp.
Bumblebee	Bombus sp.
Nine-banded armadillo	Dasypus novemcinctus
Sheet web spider (web)	Linyphiidae
Gulf fritillary	Agraulis vanillae
Purple passion-flower	Passiflora incarnata
Green anole	Anolis carolinensis
Hop plant	Humulus sp.
Orbweaver spider	Araneidae
Chicory	Cichorium intybus
Annual cicada	Family Cicadidae
Ocola skipper	Panoquina ocola
Periwinkle	Vinca sp.
Paw Paw	Asimina triloba
Long-tailed skipper	Urbanus proteus
Silver spotted skipper	Epargyreus clarus
Hairstreak	Satyrium sp.
Asian multi-colored lady beetle	Harmonia axyridis
Ailanthus webworm moth	Atteva aurea
Spider wasp	Entypus unifasciatus
Tobacco	Nicotiana tabacum
Rose pink	Sabatia angularis