EDITOR’S NOTE: Environmental Horticulture Agent III, Rebecca Jordi, addresses questions about landscaping and gardening in northeast Florida. She is the Extension Director in Nassau County, Florida and also a University of Florida faculty member.
QUESTION: What is this white stuff on my prickly pear cactus? TA
JORDI: Thanks for bringing in a sample. The pest is actually called a cochineal insect. Prickly pear cacti (Opuntia spp.) are native to the Americas. They are easy to grow and propagate making them an excellent choice for low water use landscaping.
For fun, carefully scrape some of wax mass from the plant with a knife and crush it on a piece of paper. If this results in a deep red color, then you know you have the cochineal scale (Dactylopious spp.). Cochineal remained one of the most important sources of red dyestuffs until the 1850s, when the first synthetic dyes, called aniline dyes, were produced. Cochineal is still commercially produced in Mexico and India to furnish the permanent brilliant red dye for foods, drinks, cosmetics and artists’ colors. The dye made from cochineal is often called carmine or carminic acid. You may want to look for these ingredients on the labels of some of your favorite shampoos, gelatins, fruit juices, candies, and other red-colored products.
The cochineal scale is a piercing/sucking insect which uses the cottony wax to shelter female insects and egg masses. The crawler stage is when they spread on and among cactus plants. Once settled, they spin the waxy fiber to protect them from predators and the weather. While these small insects utilize the plant for food, the damage is usually negligible. If a plant is seriously colonized and showing signs of decline, you can prune off the worst pads and discard them (always prune at the joints). Blast the remaining portion of the plant with a high pressure hose. This should expose and weaken the insects. Then spray the exposed scale with and insecticidal soap.
QUESTION: I found this strange looking caterpillar on my tree trunk. Will you identify it for me? WF
JORDI: I have received e-mails with photos of this caterpillar within the last few weeks so I know it is time to talk about it. Your caterpillar is called a puss moth caterpillar. The southern flannel moth, Megalopyge opercularis is an attractive small moth best known because of its larva, the puss caterpillar. The genus name Megalopyge are derived from the Greek roots Megalo (large) and pygidium (rump)—probably because of the shape of the caterpillars. The photos are mine from a caterpillar and cocoon attached to my garage door. In north central Florida, puss caterpillars are most common on various species of oaks but are also common on elms – including both native species and the exotic Chinese elm. Young larvae feed by skeletonizing leaves and later eat small holes in the leaves.
This caterpillar is one of the most venomous caterpillars in the United States. The venomous spines of puss caterpillars are hollow and each is equipped with a venom gland at its base. In Texas, they have been so numerous in some years that schools in San Antonio in 1923 and Galveston in 1951 were closed temporarily because of stings to children.It was reported in 1922 by Dr. Foot different severity to stings between people depending on the thickness of the skin where the sting occurred. The sting produces an immediate intense burning pain followed by the appearance of a red grid-like pattern on the skin matching the pattern of the venomous spines on the caterpillar. In addition to the characteristic localized symptoms, more general systemic manifestations may also occur including headache, fever, nausea, vomiting, irregular heartbeat, low blood pressure, seizures and more rarely, abdominal pain, muscle spasms, swelling of the lymph nodes and convulsions.
Eagleman (2008) has reviewed common treatments for puss caterpillar stings. Remedies that may be helpful in some cases include removing broken spine tips from the skin with tape, applying ice packs, use of oral antihistamine, application of hydrocortisone cream to the site of the sting, systemic corticosteroids, and intravenous calcium gluconate. The caterpillar does have natural enemies such as the tachinid fly, Hyposoter fugitivus, Lanugo retentor and Hyposotor fugitivus all of which are predatory wasps. In most years, puss caterpillars are kept under control by natural enemies. If control measures are required, chemical insecticide or Bacillus thuringiensis (Bt) applications recommended for control of other caterpillars should be effective. For more complete information, please read this University of Florida publication.
QUESTION: What kind of tree is this? It puts out hundreds of seeds. MM
JORDI: I am glad you brought in a clipping of the tree with the seeds as it made it much easier to identify. I believe you probably have a Chinese Elm. A fast-growing, deciduous or evergreen tree, Chinese Elm forms a graceful, upright, rounded canopy of long, arching, and somewhat weeping branches which are clothed with two to three-inch-long, shiny, dark green, leathery leaves. Here, in the southern extent of its range the tree remains evergreen. The bark naturally sheds which many people often mistake for disease, but can provide an interesting pattern on the trunk making it more attractive. Chinese Elm can reach 80 feet in height but is more often seen at 40 to 50 feet, making it an ideal shade, specimen, street or parking lot tree. The root system is comprised of several very large-diameter roots which can grow to great distances from the trunk. These are usually located fairly close to the surface of the soil and can occasionally lift sidewalks. They can also get into sewer lines causing damage, but they are usually not a serious problem. Consider planting far away from sidewalks and drain fields.
November 18, 2013 Plant Clinic, Nassau County Florida Extension
Becky Jordi, County Extension Director/Horticulture Extension Agent will conduct a Plant Clinic from 10 am until 2 pm at the Yulee Extension office. All Nassau County residents are invited to bring plant samples showing problems in their landscapes. Problems will be identified and solutions offered for correction. There is no fee for this service. For information call 904-879-1019. Master Gardeners are on phone duty Fridays, at 904-491-7340 to provide information and answer questions.
Rebecca L. Jordi
Nassau County Extension Director
UF/IFAS Environmental Horticulture
543350 U.S. Highway #1
Callahan, FL 32011
904 491-7340 or 904 879-1019
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