Care in the Lawn
Dr. Mario A. Villarino, County Extension Agent for Agriculture and Natural Resources
Well, it happened to me now. Last friday, as we were watering the plants at the Hopkins County Extension Office, I noticed a potential trip hazard by the garden hose. I was conducting a training in bovine artificial insemination and I got concerned with our visitors getting tangled by the hose. I went back to removed the wet hose and as I was ready to relocate it I tripped. As I was falling, instinctively I used my right hand to stop the fall. My right thumb took most of the fall, breaking my wrist. Few days later, I am wearing a cast (and it shall be there for the next 4 weeks) to heal the damage.
During my absence, a concerned citizen in Sulphur springs brought me a sample of a caterpillar affecting her orange trees. The caterpillar is an immature stage of the swallow tail (Papilio cresphontes Cramer).The caterpillar stage is commonly known as orange dog caterpillars or orange dogs or orangedogs .The adult stage is the giant swallowtail butterfly that feeds on nectar. They have a complete metamorphosis (egg, larva, pupa, adult stages). The caterpillars appear from April through September. Caterpillars feed on leaves of citrus and leaves of other plants including rue (Ruta graveolens), fennel (Foeniculum vulgare), and prickly ash (Xanthoxylum sp.) Mated females usually lay their eggs singly on the upper surface of leaves of host plants. Eggs are very small, spherical, and cream to brown. The caterpillar stage known as orange dog caterpillars are dark brown with creamy-white, mottled markings. They looks similar to bird droppings and can grow 1½ – 2" long. Caterpillars usually feed during the night , and have a special gland called an osmeterium that emits a foul odor when the caterpillar is threatened (smells like rancid butter) and is fatal to many insects.
The orange osmeterium looks like a forked snake tongue that retreats when threat is removed. Caterpillars develop through several stages (instars) before forming a brownish chrysalis, which is attached to the host plant by the back end and held in an upright position by a silk thread around the middle.Caterpillars may pupate on small twigs on the host plant on which they were feeding or they may travel a short distance to a vertically-oriented structure, such as a fence or other plant. Adult stage is a butterfly.The adult butterfly is one of the largest swallowtail species, with a wingspan of up to 6". Wings are black with yellow markings near wing margins and spots forming a diagonal band across the fore wings. Butterfly gardeners often plant citrus trees to provide food for orange dog caterpillers to produce giant swallowtail butterflies. Maturing and mature citrus trees can easily withstand the loss of a few leaves eaten by the orangedog. Homeowners may find that just a few larvae of the giant swallowtail will defoliate small, potted citrus plants. It is recommended that caterpillars be hand picked from these small plants so that leaf production and fruit yield are not drastically reduced. Young citrus trees grown in the landscape can become infested with numerous orange dog caterpillars on occasions, especially in instances where there is a single tree growing in a landscape. Orange dog caterpillars can be controlled on small trees by finding and crushing eggs and caterpillars. Caterpillars can be pick off by hand or tweezers and place in a container of rubbing alcohol or very soapy water.When present, several parasites and other natural enemies can provide satisfactory control. The bacterium Bacillus thuringiensis (commonly known as Bt) is effective if it is used against young larvae. Spray applications should be made in April to control newly emerged caterpillars. Thorough coverage of all foliage is needed. Several insecticides provided effective control of orange dog caterpillars.
Thorough coverage of all foliage is needed. Early sprays against young caterpillars are more effective than later applications against older caterpillars. Some common over-the-counter insecticides (including biological control sprays) are Green Light Bt Worm Killer, Ferti-lome Borer, Bagworm, Leafminer & Tent Caterpillar Spray, Green Light Lawn & Garden Spray Spinosad, Malathion and Carbaryl.
Program updates: The Grazing Management Field Tour is scheduled for Friday October 5th 2012 at the Lamborn Ranch, located at 1511 NW County Road 1090, in Sulphur Bluff, Texas. The tour is organized by NRCS, the Fannin-Hopkins SWCD and Texas A&M Agrilife Extension Services in Hopkins County. 2 CEU’s for private applicator will be granted. The tour is free. Call 903-583-9513 to RSVP. Our yearly Dairy Outreach Program Area Training will be conducted at the SouthWest Dairy Museum October 31, 2012. Permitted Dairies are encouraged to participate. 4 DOPA credits will be offered. The cost of the training will be $10 per person lunch included. Our yearly pesticide applicator training is scheduled for November 7, 2012 at the regional civic center. The topics for this year are of special interest for herbicide applicators and beef producers. Call the Hopkins County Extension Office for more details. The cost of the event is $25 lunch included. New pesticide applicator applicants are encouraged to participate in our multi-county pesticide applicator training scheduled for November 7, 2012. Private landowners seeking pesticide applicator licensing will have an opportunity to get the mandated training and exam in our single day. The cost of the PAT training is $10. No lunch is included. For more information on these or any agricultural topics please contact the Hopkins County Extension Office at 903-885-3443 or e-mail me at email@example.com.