Sunday, August 24, 2014

Does the IO moth caterpillar really sting?‏

IO moth caterpillar
Knowledge is a funny thing- you think you know things but often the information comes from books, the internet or other people and you do not have personal experience to confirm a fact.

Recently during an interesting presentation on local moths, the subject came up of whether IO caterpillars sting.  Based on information in books such as Wagner's "Caterpillars of Eastern North America" page 238, I had assumed that their spines can deliver a painful sting.  But I had never experienced this in person.  So it was a strange coincidence that after cutting some 8 foot tall weeds in a field with my tractor recently, I felt something crawling on my neck and whacked it with my hand.  Unfortunately the thing on my neck was the IO caterpillar shown in the attached photo.  The result was a painful sting on my neck which did not however last long.  I did not feel any stinging in my fingers when I picked the cat off my neck.  The intensity of the sting is likely related to how hard the caterpillar is squeezed and how  many spines are embedded in the skin and how deeply they penetrate.

The coloration of the IO cat is interesting- it is mostly green which seems an obvious type of camouflage.  Then there is a bright red line bordered by white along the sides; this would seem to be a warning coloration yet it is not a very obvious sign of toxicity.  The numerous spines with which the caterpillar are covered certainly are intimidating.    

So beware of the IO caterpillar- it is painful but compared to some other insect stings, such as that of the yellow jacket wasp, the honeybee, or even the nettle plant,  it seems relatively mild in my experience.  If you have an allergy to the toxin that would be a wholly different situation and much more dangerous.

Bill Dunson

Sunday, August 17, 2014

The Stealth Caterpillar



Moth Caterpillar prominent moth
Schizura ipomoeae  on blueberry at VA farm
When caterpillars are toxic, they tend to be brightly colored and some possess painful spines.  Tasty caterpillars are usually well camouflaged; some are green to resemble foliage, some mimic bird droppings or twigs, and some have various types of disruptive camouflage.  My wife was picking Japanese beetles off her prized blueberry plants and by chance found an interesting example of the disruptive camouflage type, one of the prominent moths, Schizura ipomoeae.  Although often called the morning glory prominent, one expert (David Wagner) prefers to call it the checkered-fringe prominent since this species has no special association with morning glories.  Indeed it feeds on a wide variety of woody plants and is distributed from Canada to Florida.  

Despite being common, this caterpillar is very rarely seen since it has such a spectacular means of blending in with the background vegetation.  By variation in both color, pattern and form, it is difficult for a bird to pick this tasty snack out from the plants.  You will note from views of the side and top that there is a patchwork of colors and pattern that differ depending on the orientation of the body.  The change in body shape, the angles of the dorsal surface, and types of spines also serve to disrupt the ability of a predator to pick this object out as a potential meal.  It is indeed a "stealth" caterpillar hiding among the foliage.  This camouflage appears to be so effective that it does not appear to have any defenses known from other caterpillars such as toxic spines or scary eye spots. 

Moth prominent Schizura ipomoeae (photo by Bob Perkins)
The adult moth is shown here in a photo by neighbor Bob Perkins, who catches moths on a sheet illuminated by a light at night.  It is also well camouflaged but in a more typical fashion that resembles bark.  

Evolutionary selection has presented us with a myriad of examples of how prey can elude predators by being camouflaged.  But this caterpillar provides one of the more interesting cases of how bird predation can be minimized by using patches of color, pattern and shape.

Bill Dunson , Galax, VA and Englewood, FL

Predators or Prey- Turning the Tables

Spider marbler orbweaver
Some of those animals that we consider predators may sometimes become prey in the complex world of food webs.  For example the orb weaver spiders are familiar to us since they spin large webs with concentric rings of silk to catch insects.  For example the foliate orb weaver which has a web on the outside of one of our windows has here captured a hummingbird  clearwing sphinx moth which was feeding on nectar nearby.  Their habit of sitting on the edge or center of their web must make them susceptible to attack by predators such as birds although they often sit behind the web or off to one side, or hide during the daytime.  

Mud dauber organ pipe nests
next to paper wasps
An unsuspected small predator on these large spiders is the organ pipe mud dauber wasp (Trypoxylon politum, Sphecidae), a solitary species that builds nests made of mud up under the eves of houses and barns.  The beautiful marbled orb weaver is shown after capture by a mud dauber wasp on our porch.  My photograph at our cabin shows a series of the mud tubes next to a communal paper wasp nest (probably Polistes, Vespidae) , illustrating the extreme difference in materials and behavior utilized by these wasps from different families.  The paper
Wasp with spider prey
marbled orbweaver 
wasps typically eat caterpillars whereas the organ pipe mud dauber is a specialist on spiders.  Spiders are paralyzed by stinging and placed alive with an egg laid on them in the mud tubes.  This living death technique provides a nice source of fresh food for the larvae.  The female mud dauber builds the tubes and catches spiders very large in relation to her body weight.  The male guards the nest against parasites and trespassers while the female is away.  

Orbweaver foliate Larinioides
with prey hummingbird
clearwing sphinx moth
These two types of wasps are relatively peaceful and should be easily tolerated by humans.  Whether their feeding habits are beneficial to us is debatable, since spiders kill both useful as well as pest insects.  Which do you prefer having around your house- spiders or wasps?!  Why not tolerate both as remarkable examples of the wide variety of life history strategies for survival present in the natural world.

 
Bill Dunson 

Thursday, August 7, 2014

Tegus on the loose


Here is an article in the NY Times about my former student from Penn State, Frank Mazzotti and his work with tegu lizards.  It sounds as if these large carnivorous lizards are likely to be spreading a lot more.  Any animal that is in this country in the pet trade will eventually be released into the wild.  Maybe they will eat the ground iguanas that are spreading on the western coast of FL?  It is interesting how the threat of exotic reptiles stirs the passions.

Bill Dunson

The New York Times 

A Hungry Little Squatter 

By: Rachel Nuwer 
Deer flies swarmed around Frank Mazzotti and Joy Vinci as they stooped to get a closer look at
the creature thrashing around in a metal trap they had laid off a weedy dirt road. Inside it was
what some biologists consider the most troublesome invasive species in the Everglades: not a
Burmese python, but a 24-inch lizard, the Argentine black and white tegu.

It thumped its long tail like a snare drum — a tactic the species uses to shift predators’ attention
to that expendable appendage (it can grow a new one). Ms. Vinci, a wildlife biologist, was not
fooled. Wiping her brow in the 91-degree Florida heat, she attached a cloth bag to the end of the
cage and then carefully opened it, shooing the tegu inside.

As she knotted the bag, the animal went limp, playing dead. That didn’t work either: The tegu,
along with three others trapped earlier, would be taking a one-way trip out of the marsh, in
Miami-Dade County, and to the University of Florida’s Fort Lauderdale Research and Education
Center.

Tegus (usually pronounced TAY-goos) originally came here from South America through the pet
trade. Although Dr. Mazzotti prefers cats, he can understand why people like them: They are
smart, attractive animals, patterned like an abstract Moroccan rug. They have a nasty bite, but
with enough handling, they grow docile. “They’ll crawl on you — the reptile version of
interacting,” Dr. Mazzotti said.

But like pythons and other invasive species first brought here as pets, tegus eventually found
their way into the natural environment. Once they were unleashed in Florida’s wetlands, the
warm weather, bountiful food and absence of natural predators allowed them to thrive.
Wild tegus were first spotted in 2008, scuttling around a trailer park in Florida City, south of
Miami. But their range quickly expanded, spilling into the nearby Everglades, where they took
advantage of a smorgasbord of native wildlife. The lizards have a taste for eggs — both reptile
and bird — but they will also eat small mammals, insects and fruit. “Everything they get their
jaws around, plant or animal, they seem to swallow,” Dr. Mazzotti said.

A wildlife biologist whose accent gives away his Long Island roots, Dr. Mazzotti, 65, has
worked in Florida’s swamps for nearly 40 years. He had hoped to become a marine biologist but
scrapped that plan after discovering he had crippling seasickness. On a class trip to Big Cypress
National Park, he discovered a new calling: the Everglades.

For decades, he focused his research on alligators and threatened American crocodiles, earning
the nickname “the croc doc.” But since the early 2000s, Dr. Mazzotti has turned his attention to
the dozens of coldblooded species that have invaded the Everglades, including pythons, Nile
monitor lizards, Cuban tree frogs and black spiny-tailed iguanas.

Still, he said, of all the invaders, tegus worry him the most. They are more tolerant of cold than
many reptiles, meaning they have a larger potential habitat range. Rare freezes in southern
Florida kill nine out of 10 pythons, but tegus have successfully overwintered as far north as
Panama City, on the Florida Panhandle. (The Florida Fish and Wildlife Conservation
Commission managed to wipe out that population before it could expand.) The invasion has two centers, Florida City and Riverview, southeast of Tampa. Some of the lizards escaped from
captivity or were set free by owners who no longer wanted them; scientists and officials suspect
many were released by reptile breeders on the theory that harvesting them in the wild is cheaper
than breeding them in captivity.

“We know in those two areas they’re reproducing,” said Kristen Sommers, the head of exotic
species at the Florida wildlife agency. “We’re trying to get a better handle on what’s going on in
those areas, and we’ve really been increasing our trapping efforts.”
Dr. Mazzotti is reluctant to cite specific population figures, but he notes that the number of tegus
trapped around Florida City has risen to 400 a year, from just 13 in 2009 and 21 in 2010; he
thinks that represents less than 10 percent of the total population. A time-lapse map he created to
track the invasion — yellow dots for traps, red for those that catch a tegu — resembles the
progression of a disease outbreak.

Dr. Mazzotti and his colleagues take turns hitting the field each day, checking about 30 live traps
that they bait with chicken eggs. They have also fitted several tegus with small transmitters to
track their movements, and set up cameras to monitor the species’ colonization patterns. While
the biologists focus on the invasion’s front lines, they have also recruited private trappers to
capture the lizards in well-established core areas, nicknamed “trailer park” and “rock pit.”

Rodney Irwin, a licensed tegu trapper in nearby Homestead, has collaborated with the
researchers for three years. “Everyone’s on the same page about one thing,” he said. “We’ve got
to do something about these aggressive predators. Argentine tegus are taking out animals that I
grew up with — that my dad and my grandfather grew up with.”

Rather than kill the invaders, Mr. Irwin chooses to sell them to pet dealers. “It would have been
easy for me to put on my redneck hat, grab my rifle and just start killing them,” he said. “But I
spent time with them and just fell in love.” He has more than 200 tegus and says almost all of his
shipments go out of state. Prices vary from $40 to $140.

Dr. Mazzotti said he did not care whether captured tegus were euthanized or returned to the pet
trade (preferably to destinations “like Montana or Mongolia,” he added dryly). His primary
concern is removing tegus from the environment, and he says he thinks the invasion can still be
contained or even stopped. But that will require acting quickly.

Tegu populations are creeping east toward Turkey Point Nuclear Generating Station, where
threatened American crocodiles nest; west into Everglades National Park, populated by protected
Liguus tree snails and endangered Cape Sable seaside sparrows; and south to Crocodile Lake
National Wildlife Refuge, the home of the endangered Key Largo wood rat and cotton mouse,
and more crocodiles. These rare animals or their eggs are potential prey for tegus, Dr. Mazzotti
said, adding, “We cannot wait until an invasive species demonstrates negative impacts to act,
because then it’s too late.”

Despite the threats to native wildlife, he said, efforts to tackle the tegu problem are lagging.
Attention is still primarily focused on pythons, even though that species is already so well
established that there is little hope of eliminating it. “I get weary not so much of fighting the battle to protect our resources,” he said, “but of our seeming inability to learn from past
mistakes.”

Flickr Album of Dunson Farm: Wildflower Meadow


From: wdunson@comcast.net
To:   "Doris Ratchford" 
Sent: Monday, August 4, 2014 10:51:16 AM
Subject: [Flickr] dpratchford (Doris Ratchford) shared her Flickr album with you.

WOW that is really beautiful- the way Flickr does the slide show is fabulous.

Thanks so much for sending your photos of our VA farm wildflower pollinator meadow planted in 2012.  If it is OK with you I will send this to Jeb and Andy who manage the local NRCS pollinator program which planned this for us.

Come and see us again

Bill Dunson

Black Skimmers in Sarasota‏






Some great photos here of breeding skimmers which you might be able to use.  Taken by Eva Furner.  I only wish that we could have such a colony on our islands.

Bill


From: "Furner, Eva"
To: wdunson@comcast.net
Sent: Saturday, August 2, 2014 5:13:13 PM
Subject: Fwd: Black Skimmers in Sarasota

FYI, thought you might find this of interest since you are in the area this week. - Large colony of Black Skimmers on Lido Key, on the beach just opposite the Holiday Inn. 
 
Surprisingly, the birds are coexisting on the beach with lots of human beachgoers. 
 
Well over a hundred birds.  Lots of chicks in varying stages of maturity and a few adults still sitting on eggs. 
 
Every time a parent lands with a fish, all the nearby chicks run toward the adult with wings outstretched.  Very interesting to see all the activity.
 
Eva Furner

Deer and fawns along the NRTrail‏



On a bike ride along the New River Trail from Gambetta to Brushy Creek, I stopped at the New River Bridge to admire the view.  To my surprise there was a white tailed deer female with her two fawns feeding along the edge of the river.  The large but still beautifully spotted fawns were eating some grass but were not hesitant to also get some whole milk from their Mom.

Bill Dunson
Galax, VA

Tuesday, August 5, 2014

The new naturalist trailer for the old timers‏


Now if I could hook my Rhino side by side ATV to this trailer I would be all set!

Grandpa Bill

Friday, August 1, 2014

Interesting haploa tiger moth

Clymene haploa tiger moth
Corky Dalton sent this nice photo of a Clymene haploa tiger moth taken along the Hudson R.

These day-flying tiger moths are aposematically brightly colored to indicate toxicity.   The hind wings also have a flash orange color with two simple eye spots presumably as a second line of defense against bird predation. I assume some of the toxicity comes from larval food of plants such as dog fennel and willow.

Bill Dunson