Archive for September, 2015

Yellow-Necked Caterpillars: Fall Landscape Pest

NewLSUAC-0214-CMYK-O  MasGarTM5x7_w85[1]

Yellow-Necked Caterpillars

By George Giltner, Adv. Master Gardener

Fall is the time of year to notice yellow-necked caterpillars, Datana spp. The head is black followed with a yellow to orange neck. The body is black with 4 longitudinal yellow lines on each side. White long hairs cover the 2-inch mature caterpillar body. A behavior characteristic, which also helps to ID this caterpillar, is the “C” or “U” shaped arching of the body when it is disturbed. Another behavioral characteristic is their group feeding, as large numbers are found on individual branches.

Check your blueberry bushes at least every two weeks from August till late fall. Treat bushes with Bt or Spinosad, or mechanically remove, or prune for control. These voracious feeders can entirely defoliate small bushes. This extensive defoliation will retard the growth of the blueberry bush, but it usually does not kill it due to late season leaf fall anyway. However if repeated yearly defoliations are allowed to occur, the bushes may die. In late fall the caterpillars leave the foliage, enter the soil and pupate for the winter.

Other trees and bushes affected include pecans, hickories, walnuts, apple, maple, elm, cherry, witch-hazel, and azalea. Usually no treatment is required for these trees and bushes due to natural predators including birds and predatory insects. Tachinid flies, especially Winthemia datanae, is the most common predator (Craighead, F.C. 1949. Insect Enemies of Eastern Forests. USDA Misc. Publ. #657. 679pp.).

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Image 1: The “C” or “U” shaped posture when disturbed helps to identify yellow-necked caterpillar.

 

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Image 2: Yellow necked caterpillars on Blueberry, Photo by George Giltner (August – 2015).

 

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Image 3: Remains of yellow necked caterpillars after predatory insect control.

 

 

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Wasp Stings – A Significant Medical Risk

NewLSUAC-0214-CMYK-O MasGarTM5x7_w85[1]

 

Wasp Stings – A Significant Medical Risk

By George Giltner, Adv. Master Gardener

The social wasps, paper wasps, yellow jackets, hornets, red wasps, etc., in the U.S. account for more fatalities than any other venomous animal (1). Approximately 0.5 to 4.0% is prone to “immediate hypersensitivity reactions” including life-threatening anaphylaxis. Most deaths occur within a few minutes to hours from the initial sting. Constricting of airways and throat swelling cause respiratory failure or cardiovascular collapse occurs due to a rapid drop in blood pressure (2). Therefore these stings can be quite serious.

The hot days of summer bring on numerous encounters with wasps, usually from 10 am until 6 pm. Recently, I was venturing up a ladder to the second story of my barn while a flurry of paper wasps suddenly zipped around. Needless to say, the climb became a rapid descent, then a run. One nest was on the second ladder step, and the other was at the 8-foot level. I was lucky to avoid a sting as the pheromones signal other wasps that they should also participate. Wasps are not like bees with a barbed stinger that can only be used once. Wasps have a smooth stinger that can be injected multiple times.

Wasp’s sting venom is a complex mixture of multiple compounds including proteins, peptides, enzymes and other molecules. However we can examine some of the major components to understand the medical effect of a sting (3):

  1. Acetylcholine – increases stimulation of pain nerves. Very high in hornet stings.
  2. Noradrenaline – causes constriction of blood vessels resulting in high blood pressure.
  3. Histamine – causes pain and itching. Chemical released during an allergic response.
  4. Wasp kinin – large portion of wasp venom, but it has not been understood completely.
  5. Phospholipase A – destroys cells and is a strong allergen.
  6. Phospholipase B – like A, but also used to paralyze prey.
  7. Hyaluronidase – breaks down cell walls and allows penetration of venom into tissue.
  8. Serotonin – causes irritation and pain
  9. Alarm pheromones – causes same species to attack nearby threats

The best treatment of a sting is the application of antihistamine creams, which reduces further inflammation (3). Benadryl (diphenhydramine) has proven to aid itching and rash (1). Ice soothes pain issues and reduces swelling. Wash the sting site. Continue to observe and be prepared to treat the site for bacterial infections for days afterward.

Most home remedies do not work. However it is correct that bee venom has acidic components, and wasp stings have alkaline components, but the venom quickly penetrates tissue. Therefore adding a topical treatment of alkaline (like baking soda) or acidic (like vinegar) will not be helpful. A “ chaw of tobacco” and other folk cures are also not effective. If someone is stung, it is wise to move the person into a cool environment with observers. If any allergic symptoms arise, or if the person is known to have previous allergic responses to stings, get immediate medical attention (1).

 

 

  1. www.emedicine.medscape.com
  2. www.extension.entm.purdue.edu/publichealth/insects/stinging
  3. www.compoundchem.com/chemical-composition-of-insect-Venoms.

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WaspWatch – Early Warning for Invasive Destructive Beetles

NewLSUAC-0214-CMYK-O  MasGarTM5x7_w85[1]

 

WaspWatch – Early Warning for Invasive Destructive Beetles

By George Giltner, Adv. Master Gardener

Most of us have heard about the destructive effects of the Emerald Ash Borer. This pest is metallic green, ½ inch long and 1/8 inch wide. It lays eggs on the bark of ash trees in spring, which hatch into larvae that invade the cambium, between the bark and the wood. This inner bark feeding essentially cuts off the nutrient supply to the tree’s root system. Ash trees will die within two years of an invasion. EAB is now labeled as the most destructive forest pest ever seen in North America.

We have a wasp on our side that is providing an early warning system for detection of the EAB. This native ground-nesting wasp, Cerceris fumipennis uses EAB and native beetles called buprestids as paralyzed food for its larvae in underground nests. Since the wasp will not sting us, even when handled, you can capture the paralyzed beetles. You may even capture other newly-arrived buprestids, like the European Oak Borer. Contact the Louisiana State Arthropod Museum thru www.lsuinsects.org/cerceris/LSUwaspWatcher@gmail.com. Also go to www.lsuinsects.org/cerceris/LA_waspwatcher_program.pdf for more information on this Bio-surveillance program.

Identification of Cerceris fumipennis:

  1. It is about the size of common yellow jacket wasps, however these are not the aggressive social wasps like ground yellow jackets that attack intruders in mass.
  2. It has dark blue/black wings.
  3. Unlike yellow jackets, the body is primarily black with only a few yellow markings.
  4. A conspicuous single broad yellow band encircles the front of the abdomen.
  5. It is a solitary ground-nesting wasp. A neighborhood of single entry nests will occupy an informal colony of nests. Entrance holes are about the size of a pencil.
2015 cerceris

Left: Cerceris fumipennis , Right: Emerald Ash Borer (U. Conn. Photos)

Mr. George Giltner is an Advanced Master Gardener and Tree Farmer in Beauregard Parish, LA. George is also a self-taught entomologist and write about insects in his “Battle of the Bugs” Series.

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