by Larry Williams | Apr 23, 2020
One of the things to do while stuck at home due to COVID-19 restrictions, is to look for caterpillars and butterflies in your landscape. I’ve noticed giant swallowtail butterflies (Papilio cresphontes) a little early this year. The giant swallowtail is one of the largest and most beautiful butterflies in our area. Its larval stage is known as the orangedog caterpillar. This unusual name comes from the fact that it feeds on young foliage of citrus trees.
Orangedog caterpillar. Photo credit: Donald Hall, University of Florida
The orangedog caterpillar is mostly brown with some white blotches, resembling bird droppings more than a caterpillar. When disturbed, it may try to scare you off by extruding two orange horns that produce a pungent odor hard to wash off.
I’ve had some minor feeding on citrus trees in my landscape from orangedog caterpillars. But I tolerate them. I’m not growing the citrus to sell. Sure the caterpillars eat a few leaves but my citrus trees have thousands of leaves. New leaves eventually replace the eaten ones. I leave the caterpillars alone. They eat a few leaves, develop into chrysalises and then emerge as beautiful giant swallowtail butterflies. The whole experience is a great life lesson for my two teenagers. And, we get to enjoy beautiful giant swallowtail butterflies flying around in our landscape and still get plenty of fruit from the citrus trees. It is a win, win, win.
In some cases, the caterpillars can cause widespread defoliation of citrus. A few orangedog caterpillars can defoliate small, potted citrus trees. Where you cannot tolerate their feeding habits, remove them from the plant. But consider relocating the caterpillars to another area. In addition to citrus, the orangedog caterpillars will use the herb fennel (Foeniculum vulgare) and rue (Ruta graveolens) as a food source. Some butterfly gardens plant citrus trees to provide food for orangedog caterpillars so that they will have giant swallowtail butterflies. So you could plan ahead and grow some fennel, rue or find a butterfly garden in your area for the purpose of relocating the larvae.
Yellow giant swallowtail butterfly on pink garden phlox flowers. Photo credit: Larry Williams
The adult butterflies feed on nectar from many flowers, including azalea, bougainvillea, Japanese honeysuckle, goldenrod, dame’s rocket, bouncing Bet and swamp milkweed. Some plants in this list might be invasive.
Keep in mind that mature citrus trees can easily withstand the loss of a few leaves. If you find and allow a few orangedog caterpillars to feed on a few leaves of a mature citrus tree in your landscape, you and your neighbors might get to enjoy the spectacular giant swallowtail butterfly.
More information on the giant swallowtail butterfly is available online at http://edis.ifas.ufl.edu/in134.
by Larry Williams | Mar 20, 2020
Ground-dwelling bees get a lot of attention in late winter and spring as they create large numbers of small mounds in local lawns and landscapes.
Many people become concerned as they see these bees hovering close to the ground out in their lawns and landscapes. But these bees are interesting, docile, beneficial and are unlikely to sting.
These bees are known as andrenid bees or mining bees. Andrenid bees are solitary. As the name implies, they live alone. However, they may nest in close proximity to one another but they do not form a colony or hive. They produce individual mounds with a small entrance hole. The bees are approximately ½ inch in length with a black body.
Richard Sprenkel, retired UF/IFAS Entomologist, explains their biology in today’s article.
“After mating in late winter and early spring, the female selects a site that has dry, loose soil with sparse vegetation. She excavates a vertical shaft in the soil that is approximately the diameter of a pencil and up to eighteen inches deep. Off of the main shaft, the female will construct several brood chambers that she lines with a waterproof material. The female bee provisions each brood chamber with pollen and nectar on which she lays an egg. The pollen and nectar sustain the larva until fall when the overwintering adult is formed. Early the following spring, adult bees emerge from the ground to begin the cycle again. There is one generation per year.”
The small mound of soil that is excavated from each burrow brings additional attention to the activity of the bees. As males continue to hover in the area of the burrows looking for unmated females, the bees appear more menacing than they actually are. Andrenid bees have a tendency to concentrate their nests in a relatively small area. The openings to the underground burrows may be no more than three to four inches apart.
The threat of being stung by these bees is usually highly overrated. The males cannot sting and the females are docile and not likely to sting unless stepped on, handled or threatened. While entrances to the tunnels and excavated soil may appear disruptive to the lawn, they usually are not damaging. It may appear that the grass is thin because of the bees but it is more likely that the bees are in the area because the grass was already thin. Control is usually not necessary. Because the andrenid bees forage to gather pollen and nectar, they are actually beneficial. They serve as pollinators this time of the year.
**** Photo Credited to UF / IFAS Extension Jackson County courtesy of Josh Thompson****
by Beth Bolles | Feb 27, 2020
Landscape activities have already begun in our Panhandle counties with cleanup, mulching, raking, and pruning. Our mild temperatures and days with sunshine spur us to jump into our landscape preparations for the spring growing season.
This year before you send all your debris to the compost pile or patch up thinning turf areas, consider that some landscape imperfections may actually be good for local wildlife.
We all know how important it is to plant nectar attracting plants for bees but there are other easy practices that can help promote more native bees in local landscapes. There are some solitary native bee pollinators that will raise young in hollow stems of plants. Instead of cutting all your old perennial or small fruit stems back to the ground, let some stay as a home to a native pollinating bee. This does not have to detract from the look of the landscape but can be on plants in the background of a border garden or even hidden within the regrowth of a multi stemmed plants. Plants that are especially attractive to native bees have a pithy or hollow stems such as blackberry, elderberry, and winged sumac.
The hollow stems of upright blackberries can be home to solitary bees. Photo by Beth Bolles, UF IFAS Extension Escambia County
Another favorite site for solitary bees is in the ground. These ground nesting solitary bees should not be compared to yellow jacket wasps. Solitary bees are not aggressive. Mining or digger bees need some bare soil surfaces in order to excavate small tunnels for raising a few young. Maybe you have an area that does not need a complete cover of turf but is fine with a mixture of turf and ‘wildflowers’. A few open spaces, especially in late winter and early spring will be very attractive to solitary bees.
Beneficial solitary bee mounds in the ground of a winter centipedegrass lawn area. Photo by Beth Bolles, UF IFAS Extension Escambia County
One of our fastest disappearing homes for wildlife are natural cavities. In residential sites, we often prune or remove limbs or trees that are declining or have died. If the plant or tree is not a hazard, why not leave it to be a home for cavity nesting birds and mammals. If the dying tree is large, have a professional remove hazard pieces but leave a trunk about 10-15 feet tall for the animals to make a home. You may then get to enjoy the sites and/or sounds of woodpeckers, bluebirds, owls, flying squirrels, and chickadees.
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 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.
