Stinging Caterpillars

Howdy,

  There a several species of stinging caterpillars that are native to the area, and the southern flannel moth, puss moth, or asp is in abundance currently. They feed on several species of trees and shrubs (including oak, pecan, elm, hackberry, and dwarf yaupon) and are only of minor importance as a pest on plants. The caterpillars can get up to an inch and a half in length, and can be yellow or gray to a reddish brown color. They make a unique cocoon with a trap door at one end for the moth to emerge from, and they incorporate the larval hairs into the silk. This results in a cocoon roughly the size and color of the caterpillar. The moths have about an inch and a half wingspan, are covered in long wavy hair, and have blunt rounded wings.

Adult Southern Flannel Moth
Photo: http://citybugs.tamu.edu/files/2010/05/Megalopyge-opercularis-Laura-Bellmore-Galveston-Co.jpg

  The main concern with these is the venomous spines that hide beneath the fluffy and inviting outer hairs. These caterpillars can pose a health hazard to children and gardeners. Touching one will result in intense throbbing pain and blood colored spots near the sting site. Symptoms can include headaches, nausea, vomiting, lymphadenopathy, lymphadenitis and sometimes even shock or respiratory stress. The pain from the sting site usually subsides within an hour, and the spots will usually disappear after a day or two.

Southern Flannel Moth Caterpillar or Asp
Photo: Kate Harrell

Southern Flannel Moth Caterpillar or Asp
Photo: Kate Harrell

Southern Flannel Moth Caterpillar
Photo: Sasha Azevedo- http://bugguide.net/node/view/148746

Southern Flannel Moth Caterpillar
Photo: Bart Drees- http://citybugs.tamu.edu/factsheets/biting-stinging/others/ent-3010/

Stings from the Southern Flannel Moth Caterpillar
Photo: http://citybugs.tamu.edu/factsheets/biting-stinging/others/ent-3010/

  Applying an ice pack to the sting site can relieve some of the pain, and oral antihistamines can be given to help relieve itching and burning sensations. Clear tape can be used to remove some of the spines by gently applying and stripping from the sting site. If an allergic reaction occurs, such as generalized itching or difficulty breathing, you should consult a physician immediately. You should also visit a physician if the sting site involves the eye.

  If these or other stinging caterpillars become abundant, they can be controlled with treating with Bt, spinosad, azadirachtin, or a residual insecticide such as permethrin, cyfluthrin or other sprays labelled for ornamentals. 

  For information on a few other stinging caterpillar species check out this publication, and for more info on asps look at this website. Let me know if you have comments or questions.

Sincerely,

Kate Harrell

Woolly Oak Aphid

Howdy,

  The 2016 South Texas Farm and Ranch Show is going on next week on October 19 and 20. If you would like more information, please check out their schedule on the flyer and their website. I am looking forward to attending at least one day. If you're needing CEUs, this is a good opportunity to get them.

  My most common insect questions this week have been on the Woolly Oak Aphid. Like other aphids, they feed on the plant sap. This species can practice parthenogenesis, which means that a colony of females can reproduce without the need for any males. They give live birth, and are often capable of reproducing in as little as 4 days. They are native to North America, and excrete the fluffy wax as a defense mechanism against their numerous predators and parasitoids.  I used a pen to scrape away some of the wax to show the aphids underneath in the pictures below. Sooty mold will often accompany this insect if the populations are large. The mold grows as a result of the honeydew this insect excretes as a waste product.

  Depending on how large your tree is, hosing the tree down can offer some relief from these insects. If the wax is washed away, not only will some of the aphids go with it, but the remaining aphids will be much more susceptible to predation. If the tree is too large to rinse off, or if the infestation is really severe and the tree's appearance is important, using a systemic insecticide with imidacloprid will kill them as well. Most of these tree treatments take a month or so to show any effect, but the protection lasts between 6 months to a year depending on which treatment you choose.

Woolly Oak Aphid
Photo: Kate Harrell

Woolly Oak Aphid
Photo: Kate Harrell

As always, feel free to contact me if you have any comments or questions.

Sincerely,

Kate Harrell

Walnut Caterpillar

Howdy,

  On September 28 TDA extended the cotton stalk destruction deadline for Wharton, Jackson and Matagorda counties to October 15. I've still seen some pickers in the fields, but I'm glad to see this season wrapping up. The cooler weather has at least made harvesting a little more pleasant.

Walnut Caterpillar
Photo: http://entomology.osu.edu/bugdoc/Shetlar/factsheet/ornamental/FSwalnutcat.htm

  Lately I have gotten a few questions on Walnut Caterpillars in the area. These insects feed on a pretty wide variety of woody shrubs and deciduous trees in the walnut family, as well as birch, oak, willow, honeylocust and apple trees. They are native to North America, and range from the eastern United States to Minnesota, Oklahoma, Kansas and Texas. The insect overwinters as a pupa in the soil, and emerges as an adult in the late spring. The females lay egg masses of 600 or more on the underside of leaflets on their host plants. Caterpillars emerge about 9 days after the eggs are laid, and unlike similar looking relatives, these caterpillars do not build webs. Young caterpillars skeletonize leaves, while older caterpillars will consume the entire leaf. After about 23 days, the caterpillars will have molted 4 times, and will then move to the soil to molt into the pupal stage. The last instar (stage between molts) will feed independently rather than with the colony, as they were up until this point. In this area we can have up to 3 generations of walnut caterpillars a year. These caterpillars are usually kept in check by natural predators, and you can achieve some control on small trees by removing the egg masses. On large trees and acreage, insecticides containing Bt or spinosad work well. These work best when applied while the caterpillars are still small, and are applied thoroughly to the entire canopy. For more information check out Bill Ree and Marty Jungman's publication on walnut caterpillars here.
  As always, feel free to contact me if you have any questions or comments.

Sincerely,

Kate Harrell