New York State IPM Program

September 28, 2016
by Mary M. Woodsen
Comments Off on Move Over, Medusa: Pretty? Poisonous! in the Caterpillar Clan

Move Over, Medusa: Pretty? Poisonous! in the Caterpillar Clan

Our gratitude to Paul Hetzler, CCE St. Lawrence County, for letting us use this post. The IPM connection? ID those fuzzy beasts before you add them to your “warm and fuzzy” petting zoo. 

When I was a kid I was fascinated by caterpillars but had trouble with the word. To me, the sweet little woolly-bear traversing my hand was a “calipitter.” It was only years later I learned that a calipitter is an instrument used to measure the diameter of a caterpillar to the nearest micron.

Caterpillars continue to interest me, although I no longer find them universally cute. Imagine the letdown and loss of innocence following the discovery that some of these fuzzy, fascinating, gentle creatures that tickled their way across my hand were venomous. This revelation was akin to finding out Bambi was a dangerous carnivore, which in fact is a fear that haunts me to this day.

Stunning — and striking in a not-so-nice sort of way. Courtesy Wikimedia Commons.

Stunning — and striking in a less-than-pleasant sort of way. White-marked tussock moth larvae, courtesy Wikimedia Commons.

It seems a further injustice that many of the so-called “stinging-hair caterpillars” are among the cutest and most colorful out there. But at least they are not aggressive the way yellow jackets can be. They are strictly defensive, the defense being hollow hairs connected to poison glands that secrete toxins. The chemical cocktail is species-specific, and often involves serotonin, histamine, formic acid and various amino acids.

The hairs inject their charge only when the critter is roughly handled. Or falls down your shirt, or gets in your sleeping bag, or is pressed against your skin in some other way. Their stings cause a painful rash which could persist a week or more. Some people have more severe reactions requiring medical treatment.

You’d think poisonous caterpillars would be from exotic locales, but to my knowledge all in our region are natives. One large group is the tussock moth clan. These caterpillars look about as terrifying as teddy bears. Two examples are the hickory (Lophocampa caryae) and white-marked (Orgyia leucostigma) tussock moths, common locally. I’ve had many encounters with these and their kin over the years.

Hickory tussock caterpillars are mostly white, peppered with a smattering of longer black “whiskers.” White-marked tussock moth larvae look like they’re fresh out of clown school, with a yellow-and-black striped pattern, bright red head, a pair of super-long black appendages as a headdress, a row of lateral white hairs on each side, and four bright yellow (sometimes white) tufts behind their heads like a row of smoke stacks.

The stubby brown hag moth caterpillar (Phobetron pithecium) definitely does not look like a caterpillar. It could easily be mistaken for a dust-bunny or bit of lint. Sometimes known as the monkey slug, this oddity has eight furry, arm-like appendages and should get a prize for its resemblance to a plush toy. If you come across the monkey slug, do resist the impulse to cuddle it.

Much like the way poison-arrow frogs dress flamboyantly to advertise they’re a poor choice as prey, some toxic caterpillars have paint jobs even brighter than those of the tussock moths. For example, the brilliantly attired stinging rose (Parasa indetermina) and saddleback (Acharia stimulea) caterpillars might make you think some practical joker has set out miniature party piñatas. Eye-catching and bristling with barbs, no one is going to mistake them for a plush toy.

Fortunately, many poisonous caterpillars look the part. The Io moth (Automeris io), a huge moth bearing a striking eye-spot shape on each wing, starts out as a neon-green (red until its first molt) caterpillar crowded with serious-looking barbs. Going further afield, the giant silkworm moth caterpillar (Lonomia oblique) of southern South America has been responsible for as many as 500 human deaths — and it looks terrifying, too.

Keep in mind that just about every fuzzy caterpillar, venomous or not, can induce asthma. Those hairs are fragile and readily become airborne. Pests such as the eastern and forest tent caterpillars — and gypsy moths too — sometimes  occur in numbers so great enough to trigger asthma, especially in children. Even the beloved woolly bears (many species of the family Arctiinae) trigger attacks in some people.

What to do for a sting? Use Scotch or packing tape on your skin to pull out embedded caterpillar hairs (along with a few of your own). Wash the area and isolate clothing you think might harbor stray hairs. Monitor for several hours for signs of a serious reaction and otherwise treat the rash the way you would any sting with calamine lotion, antihistamines, or hydrocortisone lotion as directed by your doctor.

Let’s hope that having a few bad apples around will not keep you from appreciating caterpillars. Even the ugliest ones grow up to be moths and butterflies, many of which are beautiful. And they’re all important pollinators. Stay away from the ones described here but feel free to investigate all others.

Just be sure to take along your callipitter.

 

September 21, 2016
by Mary M. Woodsen
Comments Off on Trees and Drought Make for Less Colorful Fall (and the IPM Connection)

Trees and Drought Make for Less Colorful Fall (and the IPM Connection)

Many thanks to Paul Hetzler, CCE St. Lawrence County, for permission to use this piece.

It turns out that, in terms of fall foliage, the color of too dry is officially known as “blah.” This would undoubtedly be the least popular color selection if it was included in a jumbo pack of Crayolas. Basically, it is a jumble of faded hues with a mottled brown patina throughout. This year’s dry summer could mean that “blah” may feature prominently in Mother Nature’s fall hardwood forest palette.

Why would a prolonged lack of moisture affect autumn color? Let’s look at what makes leaves colorful in the first place. Among the things we learned — and probably forgot right away — in Junior High Biology is that leaves are green because of chlorophyll, the amazing molecule that converts light, water and carbon dioxide into sugar and oxygen. Its intense green tends to mask colors such as orange and yellow that are present in leaves in lower concentrations. When chlorophyll dies off in the fall, those “weaker” colors are revealed.

The Adirondacks in full autumnal glory — but not in the mega-drought of 2016.

The Adirondacks in full autumnal glory — but not in the mega-drought of 2016. Photo courtesy Sharp Swan.

It’s not like yellow and orange are just randomly painted on the insides of leaves, though. Molecules other than chlorophyll are involved in various metabolic pathways within a leaf, and they happen to be colorful. By comparison, we are boring. Our hemoglobin is red, at least in the presence of oxygen, but we are not as flamboyant on a cellular level as leaves are.

Red, however, is a horse of a different color where leaves are concerned. Trees spend energy that they would otherwise save for next year’s growth to make the molecule responsible for red. It is called anthocyanin, mostly because short words embarrass scientists, and it is “expensive” for trees to make. No one knows why trees do this. OK, there are some explanations out there, but they are so flimsy they don’t even hold up in the rain.

In wintertime, I make my own bread. Although quality varies because I never use a recipe, more than likely the bread would turn out worse than usual if I omitted water. Similarly, all the ingredients need to be there for photosynthesis to work properly. When water is in short supply, production at the sugar factory, also known as the chlorophyll molecule, drops off sharply.

Without sugars, many cellular processes slow or even stop. Damaged chlorophyll is not replaced, and that deep forest-green color starts to pale. Those yellow and orange molecules (xanthophylls and carotenes, if you are insecure about word length) also begin to disappear.

As trees dry out further, their leaves start to brown along their edges. This is called marginal scorching, not to be confused with marginally scorched, which describes my bread. In drought-prone locations with thin soils, some tree leaves will entirely brown and turn crisp, calling it quits for the year. This of course is not good for trees, because they are not able to plug up the vascular connections between leaves and twigs, making them prone to even more desiccation over the winter.

As if that isn’t enough sepia tones for one season, our sugar maples once again are looking tawdry due to yet another infestation of the native maple leafcutter. This is a tiny colorful moth whose newly hatched larvae eat circular patterns inside leaves, eventually getting big enough to emerge onto the leaf surface and excise little holes in it to make a mini turtle-shell case for itself. A single infestation causes only minor harm to the maples, but repeated infestations can weaken them somewhat.

Between marginal scorch, brown leaves, holey maples and a general shortage of leaf pigments, we might not get the brightest display this fall. Cool nights and sunny days tend to favor the production of red in the few tree species capable of producing it, and this could at least offset the brown tinge that infuses our woodlands at present. Here’s hoping for a good crayon selection this autumn.

The IPM Connection? Well, you can’t run the well dry trying to keep your trees happy. But worse yet would be thinking your trees have some horrid disease and it’s time to dash over to the garden center for a jug of fungicide. In this case you’ve got two fundamental IPM precepts to guide you now and for the future: an accurate diagnosis and preventive action.

  • Identify (i.e. diagnose) your problem before you act. Trees that look sick or pest-ridden could suffer instead from to a surfeit or lack of three critical things their fine feeder roots need: the oxygen, water, and nutrients. Because if those roots aren’t happy, neither is your tree.
  • Prevent the problem: learn which trees will work for your landscape and how to help them deal with the hand Nature deals them. Right plant, right place, proper care: these help reduce infestations and impacts of pests.

Check out this helpful guide.

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