by Carrie Stevenson | Feb 18, 2020
Several Extension offices in the Panhandle are collecting air potato bulbils for National Invasive Species Week. Photo credit: Esther Mudge, Escambia County
The non-native invasive air potato vine (Discorea bulbifera) has wound its way throughout Florida, from pine forests and creek floodplains to backyards. Their heart-shaped leaves are most noticeable in the spring and fall, where they can take over large areas, not unlike their fellow invasive vine, kudzu. In the fall, the plant produces a potato-like tuber called a bulbil, which grows above ground on the vine. The bulbils drop in the winter and then produce new vines the following spring.
The vine’s growth has been uncontrolled or kept back by herbicide for years, until researchers discovered a biological control insect known as the air potato leaf beetle (Liloceris cheni). In the vine’s native Nepal and China, the beetle controls growth by surviving on the leaves of the air potato, its sole food source. After extensive study, the USDA approved the use of these beetles in Florida to control the air potato vine population here. UF IFAS Extension offices statewide have participated in these beetle release programs, providing thousands of beetles to homeowners and property owners seeking to manage the invasive vine using a chemical-free technique. Left alone, air potato vines can smother full-sized trees, blocking the sunlight and causing them to collapse under the weight of the intertwined vines.
From 2012-2015, beetles were able to reduce air potato vine coverage and bulbil density by 25-70% (depending on location and density of beetle population). The active beetle-production phase of a UF IFAS grant has ended, but researchers are committed to the goal of reducing this nuisance species statewide.
To assist with this process, several Extension offices in the Panhandle are sponsoring a bulbil collection during National Invasive Species Week (NISAW, February 23-29). This effort will serve two important roles: to remove bulbils from the natural environment and to provide a seed source for university researchers seeking to grow air potato vine in a controlled environment, sustaining a continued population of air potato beetles for distribution.
For more information on Air Potato Vines and Leaf Beetles, visit https://bcrcl.ifas.ufl.edu/airpotatobiologicalcontrol.shtml or contact your local County Extension office.
by Mark Tancig | Jan 13, 2020
I was recently asked what kind of fungus was affecting a plant brought into the UF/IFAS Leon County Extension Office. Upon close inspection, it was not a fungus at all, but turned out to be damage from spider mites and the little critters were right there on the plant.
Spider mites along the bottom of the leaf. Credit: Mark Tancig, UF/IFAS.
Spider mites, as the name implies, are eight-legged creatures that are kin to spiders and in the mite and tick group of arachnids. They can cause damage to ornamental, fruit, and vegetable plants, especially in hot, dry weather or when grown in greenhouses or indoors. The plants that came into the office had been growing in a greenhouse.
Spider mites are a piercing, sucking pest that pierce their mouthparts into the leaf tissue to suck out nutritious plant saps. High densities of spider mites can pull enough plant tissues out to cause a light colored, grayish look to the leaves, somewhat resembling downy mildew damage. Upon close inspection, small brown to red dots on the bottom of the leaf and/or spider web-like webbing along the stem and petioles may be observed, confirming the identification of spider mites.
Webbing caused by high numbers of spider mites. Credit: UF/IFAS.
Plants grown outdoors don’t usually experience spider mite damage, as natural predators such as lady beetles, minute pirate bugs, thrips, and lacewings provide biological control. For spider mite infestations on houseplants or in greenhouse operations, control can be achieved through physical and chemical control. As part of an integrated pest management plan, regular monitoring of these plants can help identify problems before they get too bad. Sprays of water and rubbing undersides of leaves can remove many spider mites and provide control of small populations. If that doesn’t take care of them or they are at infestation level, insecticidal soaps and horticultural oils can provide adequate control.
Remember that correct identification is key to properly controlling a pest. If the damage was treated as a fungus and a fungicide sprayed, the pest would not be controlled, and time, money, and product would be wasted. If you have questions regarding what is ailing your plants, contact your local UF/IFAS Extension office.
by Matt Lollar | Jan 13, 2020
Scale insects on a cabbage palm (Sabal palmetto). Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
This week I was on a couple site visits to look on some cabbage palms (Sabal palmetto) and some banana shrubs (Michelia figo). The palms had a white, waxy substance on their frond petioles and the banana shrubs had white specs on the tops of their leaves. Upon further investigation, I realized the waxy substance and specs were both different species of scales. Scale insects are serious pests of a number of ornamental plants. Here in Florida there are 13 different families of scales with the most common being armored scales, soft scales, and mealybugs. Scales have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental plants. Heavy infestations cause extensive leaf yellowing, premature leaf drop, branch dieback, and eventually plant death.
Scale Biology
The life cycle of a scale begins with eggs being laid beneath wax coverings or beneath the adult female. Eggs typically hatch in 1 to 3 weeks. The newly hatched nymphs, called crawlers, move around a plant until they find a spot to feed. Once a feeding site is located, their piercing sucking mouthparts are inserted into the plant and the crawlers begin to feed and grow. The males of many scale species develop wings as adults and fly to other plants to reproduce.
Magnolia white scales on a banana shrub (Michelia figo). Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Armored Scales
Armored scales get their armor by secreting a waxy covering over their bodies that is not attached. The scale lives under this covering and uses it as a protection to feed under. Armored scales can be almost any color or shape and range anywhere from 1/16 to 1/8 inch in diameter. For females, these shapes range from circular to oval to long and slender. The males typically have coverings that are more elongate and smaller than the females. As adults, the males are tiny, winged, gnat-like insects and are rarely seen.
Gloomy scale (Melanaspis tenebricosa) with armored covering removed. Photo Credit: A. G. Dale, University of Florida/IFAS
Soft Scales
Similar to armored scales, soft scales secrete a waxy covering, but it is attached to their bodies. Soft scales can be a number of colors, shapes, and sizes and range anywhere from 1/8 to 1/2 inch in diameter. Their shapes vary from spherical to nearly flat.
Population of adult and immature tuttle mealybugs (Brevennia rehi) on a blade of zoysiagrass. Photo Credit: Lyle J. Buss, University of Florida/IFAS
Mealybugs
Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments. They are about 1/8 inch in length and usually pinkish or yellowish in color. Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental plants. Mealybug damage produces discolored, wilted, and deformed leaves.
Scale and Mealybug Management
- Cultural Control – Plant inspection prior to purchase or installation is the first line of defense against a scale or mealybug population. Make sure to inspect the undersides of leaves and plant stems. Infested sections of plants can be pruned and plant material should be cleaned from the planting area and discarded. Also, you can increase air flow and decrease humidity by proper installation and pruning. Over-fertilizing can also increase pest populations.
Larva of a brown lacewing. Credits: Lyle Buss, University of Florida.
- Biological Control – Predators, such as ladybugs and green lacewings, are usually present in large enough numbers to suppress scales and mealybugs to a desirable threshold. However, broad-spectrum insecticides and bad weather can reduce predator numbers. Look for signs of predation by inspecting dead scales for jagged holes in their waxy coatings. If predation signs are present, use more selective chemical controls and oils as opposed to broad-spectrum products.
- Chemical Control – Timing is everything when it comes to managing scale and mealybug insects. Crawler activity is more pronounced with the flush of new plant growth in the spring. Before application, prune infested plant parts off first to promote greater penetration of insecticides into the foliage. Dormant Oils are often used in the winter to smother scale insects. These are good choices to implement because they don’t harm non-target or beneficial insects. Care must be taken to read the label and use them at the correct temperature, since use in hot weather may burn foliage. Contact products (acephate, bifenthrin, carbaryl, etc.) must be applied to inhibit the crawler stages of these insects and systemic products (acetamiprid, imidacloprid, thiamethoxam, etc.) can be used on the sessile growth stage. Plants should be sprayed thoroughly to the point of drip or “run off” from leaves, twigs, and stems. Repeated applications may still be necessary even if the timing is right, as crawler populations are often large and crawlers like to hide under old waxy scales. Systemic drenches are also a viable option. With good spray coverage, horticultural oils can kill scales at all stages of growth. Refer to the product label for phytotoxicity and temperature guidelines. Even after successful treatment, the outer coatings of the scales may remain on the plant material for weeks, which can be unsightly. The best way to determine if scales are dead is to squeeze them. They will be dry when squeezed if they are dead and they will ooze liquids if they are living (they were at least alive to the point of being squashed).
For insect identification and additional information on scale control, please see:
A Guide to Scale Insect Identification
UF/IFAS Featured Creatures
Your County Extension Office
by Molly Jameson | Dec 10, 2019
This velvet ant (Dasymutilla occidentalis) is a female, and therefore has no wings, but it does have a long ovipositor that could inflict a painful sting if provoked. Photo by Johnny N. Dell, Bugwood.org.
The Docile Nature of a Cow Killer
Has a large, flashy, bright red-orange, fuzzy ant-like creature ever captured your attention? It may have been the infamous velvet ant, otherwise fittingly known as “cow killer” for the very painful sting it can inflict. A solitary species that builds no nest of their own, you’d likely only see one at a time, perhaps crawling over bare soil or along a tree root.
This velvet ant (Dasymutilla occidentalis) is a male, and therefore has wings, but no stinger. Photo by Johnny N. Dell, Bugwood.org.
Velvet ants are actually not ants at all, but wasps. They are wasps that – although capable of stinging humans and other large animals – are not aggressive and have venom with relatively low toxicity (less than that of a honeybee). That said, an accidental sting by the female’s long ovipositor inflicts serious pain that one would not soon forget.
Velvet ants are in the Mutillidae family, which contain about 8,000 species throughout the world. But only fifty Mutillidae species can be found in Florida, as most prefer arid regions, such as the southwest United States.
If you see a velvet ant with wings, rest assured, it is a male. Although capable of flight, males are incapable of stinging, as they lack stingers. Females, who lack wings, need a suitable host to be able to lay their eggs, and they spend most of their time looking for one. They rely mainly on mature larvae (such as pupae and cocoons) of other solitary species in the Hymenoptera order (other wasps, bees, and ants) to parasitize. That is, a female adult velvet ant will forcibly enter a nest to deposit an egg beside its larval victim. When the velvet ant larva emerges, it will consume this host within about a week before it matures and emerges from the host nest to seek a mate.
Adult velvet ants feed on flower nectar. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org.
The “velvet” part of velvet ant refers to the dense heap of hairs covering top portions of its body, which is usually a bright shade of red or orange, although some species are gold, silver, black, or white. Velvet ants use their aposematic coloration to their advantage. They tell potential predators “don’t mess with me” through their visually striking, often red and black “stripes,” that act as a visual defense mechanism.
Beyond coloration, a female velvet ant will also produce a warning sound when provoked, further evidence that she wishes to remain docile, rather than fight. Despite their gory parasitism on which they rely to reproduce, adults simply feed on nectar.
So, the next time the mesmerizing bright red streak of a velvet ant catches your gaze, keep your distance, but have no fear, for this cow killer comes in peace.
by Larry Williams | Dec 4, 2019
Fire ant control options in some situations include doing nothing.
Fire ant colonies consist of the brood (eggs, larvae and pupae) and adult ants. The adults include winged males, winged females, one or more egg producing queen and workers. The winged males and females mate in spring or early summer after a rainy period. Males die shortly after mating. Newly mated females can fly as far as twelve miles from the nest (or farther carried by wind). After landing, mated females shed their wings and begin digging chambers in which they lay eggs to start a new colony.
A single queen can lay over 2,000 eggs per day! She can live an average of six to seven years. A mature fire ant colony may contain 100,000 to 500,000 workers. Fire ant mounds/colonies can reach densities of 200 to 800 per acre.
You should now begin to understand why fire ants are difficult to control. Where they don’t present a direct threat to human health, the best management practice may be to leave them alone.
Homeowners may have to find a tolerable level. Waging war on this insect can be expensive and requires a long-term commitment. There is no single, universal solution to controlling fire ants. A one-time treatment may make the problem worse. In areas where native ants and fire ants have been reduced or eliminated with insecticides, reinfestation by fire ants into these treated areas is rapid.
A balanced approach to fire ant management is recommended. Those mounds that pose no threat to humans should be left alone. Instead target specific mounds such as those close to buildings and walkways.
When treating single mounds with contact insecticides, it’s critical to treat when the queen and brood are close to the surface, which is between 70ºF to 85ºF. When using fire ant baits, it’s important to apply the bait when the ants are foraging for food. They are most actively doing that between 70ºF to 85ºF. Actively foraging ants will pick up the bait and carry it into the nest within minutes. That’s important because baits tend to quickly go rancid and then are no longer attractive to ants. When using season-long control products, it’s a must to achieve uniform coverage of the area. Always read and follow the label precautions and directions when using any insecticide.
Where fire ants create no threat in out-of-the-way areas on your property, consider the option of leaving them alone.
The following link to a UF/IFAS Extension publication provides options for fire ant control in lawns, gardens and landscapes. http://edis.ifas.ufl.edu/lh059
by Carrie Stevenson | Nov 7, 2019
A female striped lynx spider protects her egg sac. Photo credit: Carrie Stevenson, UF IFAS Extension
With Halloween just behind us, some of us may still have fake spiders in our yards and cotton webbing all over the shrubbery. Spiders (along with bats) are among those creatures feared and demonized in folklore this time of year. It is important to remember, however, that both organisms are important predators and managers of our insect population.
Last week during a walk on the Extension property, I came across a large brown spider hovering protectively near her egg sac. Perched in a newly planted pine tree, I saw no obvious web. Instead, the spider loosely wrapped the pine’s needles with silk, forming a support structure for the relatively large egg sac.
Newly hatched striped lynx spiderlings on silk scaffolding covering a plant. Photograph by Laurel Lietzenmayer, University of Florida.
On further research, I learned that this female striped lynx spider (Oxyopes salticus) would have mated just once, after responding to a male’s courtship display (involving drumming and elaborate leg touches). She would have produced the egg sac 1-4 weeks after mating, attaching it to the pine needles, and will tend to it until her young emerge 20 days later. Up to five days after hatching, lynx spiderlings disperse by “ballooning” from the plant—they release a silk thread into the air, allowing the wind to carry them off like a tiny skydiver. Those spiderlings will mature into adults by 9 months, living their entire lifespan in just one year.
During that year, though, lynx spiders are important predators of pest insects. Instead of catching bugs in a web, they stalk their prey like a big cat—hence the name, “lynx.” They prey on many fly species, but also on bollworms and green stinkbugs that are major pests of cotton and soybean crops. These spiders are beneficial and highly vulnerable to insecticides.
