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.
by Mark Tancig | Sep 16, 2019
Paper wasps can hide among vegetation and surprise gardeners. Credit: UF/IFAS
As summer comes to a close, many gardeners are getting their landscapes back in shape after the long, hot summer months. There are likely some large weeds and/or vines that have taken over areas where they are not wanted. As you begin to hack these back, it is wise to be on the lookout for wasps and yellow jackets. These stinging insects pack a punch and are particularly active this time of year.
Wasps and yellow jackets are closely related in the insect family Vespidae. These are social insects, similar to ants and bees, that have a division of labor with a queen and workers (both female) carrying out specific tasks for the colony. Males arise from unfertilized eggs and are only needed for reproductive purposes. Once they mate with a female from another nest, they die. Once the fertilized females emerge in late fall, they will overwinter under the bark of a log, or other safe habitat, until spring, when they start a new colony. Unlike bees, who die after a single sting, wasps, yellowjackets, and hornets can sting multiple times. Yellowjackets and hornets even emit an alarm pheromone that causes other members of the nest to aggressively defend the colony.
While there are many different species of wasp in Florida, including the paper, red, mason, potter, and mud dauber wasps, the paper and red wasps (Polistes spp.) are the ones that tend to be most aggressive when provoked and cause a harmful sting. Their nests are often found under house eaves or hidden in amongst shrubbery. These nests hidden in vegetation are the ones that gardeners typically run into when trimming or weeding.
There are three species of yellowjacket in Florida, including the eastern yellowjacket (Vespula maculifrons), southern yellowjacket (Vespula squamosa), and baldfaced hornet (Dolichovespula maculata). All three can be aggressive and sting humans, especially if they feel threatened, such as when pruning or working over or near a colony. Yellowjackets build extensive colonies underground, though can also build colonies in hay, palm fronds, and other loose debris aboveground. These underground colonies usually have a single entrance but can also have multiple entrance holes. Hornets build aerial colonies. Gardeners are most likely to have run-ins with yellowjackets since hornet nests are typically up in trees and more obvious than an underground yellowjacket colony.
Southern yellowjackets create underground colonies that can hold over 2,000 yellowjackets. Credit: UF/IFAS
While these insects can be a major pain, figuratively and literally, they actually do help out us gardeners. The main food source of wasps, yellowjackets, and hornets are caterpillars and beetle larvae, which are often garden pests. They are also native pollinators. Therefore, it’s best that we accept some in the landscape, manage colonies in high-traffic areas, and prevent encounters with them. To reduce your chance of weeding right into a wasp nest, take a stick and knock around the vegetation to see if any are hiding in the brush before getting started. Be ready to run. Yellowjackets are harder to avoid as they are stealthy in their underground bunkers.
When it comes time to remove these insects from near a structure or heavily trafficked area, you may want to consider hiring a professional pest control company. Wasps can be managed by most homeowners with a broom (if the nest is small and/or relatively inactive) or aerosol insecticides specifically formulated for wasp control. Yellowjackets and hornets are trickier to deal with and should be approached very cautiously. Spraying aerosols into a yellowjacket entrance hole is dangerous and may not be very effective as some colonies can be up to a foot wide and contain over 2,000 yellowjackets. Any attempts to control wasps, yellowjackets, and hornets should be done in the evening when they are less active and with appropriate clothing that covers the skin.
Yellowjackets are pollinators and eat caterpillar pests! Credit: Whitney Crenshaw, Colorado State University, Bugwood.org
For more information on wasps, yellowjackets, hornets, and other stinging insects, see the Biting and Stinging Insects section of the UF/IFAS EDIS site (https://edis.ifas.ufl.edu/topic_biting_and_stinging_pests) or contact your local Extension Office.
by Matt Lollar | Sep 7, 2019
A couple weeks ago, I was on a site visit to check out some issues on Canary Island Date Palms. The account manager on the property requested a site visit because he thought the palms were infested with scale insects. He noticed the issue on a number of the properties he manages and he was concerned it was an epidemic. From a distance, lower fronds were yellowing from the outside in and the tips were necrotic. These are signs of potassium deficiency with possible magnesium deficiency mixed in.
Transitional leaf showing potassium deficiency (tip) and magnesium deficiency (base) symptoms. Photo Credit: T.K. Broschat, University of Florida/IFAS Extension
Nutrient deficiencies are slow to correct in palm trees. It’s much easier to prevent deficiencies from occurring by using a palm fertilizer that has the analysis 8N-2P2O5-12K2O+4Mg with micronutrients. Even if the palms are part of a landscape which includes turf and other plants that require additional nitrogen, it is best to use a palm fertilizer with the analysis previously listed over a radius at least 25 feet out from the palms. However, poor nutrition wasn’t the only problem with these palms.
Upon closer look, the leaflets were speckled with little bumps. Each bump had a little white tail. These are the fruiting structures of graphiola leaf spot also known as false smut.
Graphiola leaf spot (false smut) on a Canary Island Date Palm. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Graphiola leaf spot is a fungal leaf disease caused by Graphiola phoenicis. Canary Island Date Palms are especially susceptible to this disease. Graphiola leaf spot is primarily an aesthetic issue and doesn’t cause much harm to the palms infected. In fact, the nutrient deficiencies observed in these palms are much more detrimental to their health.
Graphiola leaf spot affects the lower fronds first. If the diseased, lower fronds are not showing signs of nutrient deficiencies then they can be pruned off and removed from the site. All naturally fallen fronds should be removed from the site to reduce the likelihood of fungal spores being splashed onto the healthy, living fronds. A fungicide containing copper can be applied to help prevent the spread of the disease, but it will not cure the infected fronds. Palms can be a beautiful addition to the landscape and most diseases and abiotic disorders can be managed and prevented with proper pruning, correct fertilizer rates, and precise irrigation.
by Daniel J. Leonard | Aug 15, 2019
By Evan Anderson, Walton County Agriculture Agent:
Gardening is an attractive pastime, not only for homeowners but also, it seems, for every critter out there that wants a free meal. If a gardener isn’t trying to keep deer, rabbits, or moles out of their crops, they’re fighting against insects of many
Aphids come in many colors, but are a common (and unwelcome) sight on garden plants. Photo courtesy Evan Anderson.
different sorts. With as many different sorts as there are, it can be dizzying to try and keep track of them and to figure out what’s doing damage to which vegetables.
Just because you see an insect in your garden doesn’t mean it’s a bad one. There are many that can be friends to a gardener, patrolling the plants to snack on pests. It’s important to know what you’re looking at before you try to control them; you might end up killing off a helpful bug instead of one that’s a problem!
It can be helpful to look at the damage done by the insects that are plaguing your garden to figure out what kind they are. Piercing / sucking insects drink the fluids from inside plant tissues, and leave small dots or stippling marks, and may exude honeydew, a stick fluid that sometimes grows sooty mold on
Honeybees are an example of a good bug to find in your garden. They help pollinate crops. Photo courtesy Evan Anderson.
it. These bugs include aphids, scales, mealybugs, spider mites, stink bugs, and thrips.
Chewing insects are those that usually go after plant leaves. They chew holes, and if an infestation is bad, they might defoliate a plant very quickly! Caterpillars, grasshoppers, and some beetles are the worst offenders of this sort.
If you need help identifying or figuring out how to control an insect in your garden or any other horticultural topic, feel free to contact your local UF/IFAS Extension office!
An example of damage from piercing/sucking insects. Photo courtesy Evan Anderson.
by Sheila Dunning | Aug 7, 2019
Damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida. Severely damaged leaves become heavily discolored and eventually dry or fall off. Symptoms may sometimes be confused with mite injury, but the presence of black varnish-like excrement, frequently with cast skins attached, suggest lace bug damage (Johnson and Lyon 1991).
You may be noticing the color disappearing from your azaleas right now. Do your azaleas look bleached out from a piercing-sucking insect. The culprit is probably azalea lace bug, Stephanitis pyrioides. This pest overwinters in eggs on the underside of infested leaves. Eggs hatch in late March and early April. The insect then passes through five nymphal instars before becoming an adult. It takes approximately one month for the insect to complete development from egg to adult and there are at least four generations per year. Valuable plants that are susceptible to lace bug damage should be inspected in the early spring for the presence of overwintering lace bug adults, eggs and newly-hatched nymphs. Inspect these plants every two weeks during the growing season for developing lace bug infestations.
Both adults and nymphs have piercing-sucking mouthparts and remove sap as they feed from the underside of the leaf. Lace bug damage to foliage detracts greatly from the plant’s beauty, reduces the plant’s ability to produce food, decreases plant vigor and causes the plant to be more susceptible to damage by other insects, diseases or unfavorable weather conditions. The azalea can become almost silver or bleached in appearance from the feeding lace bug damage.
However, lace bugs often go undetected until the infested plants show severe damage sometime into the summer. By then several generations of lace bugs have been weakening the plant. Inspecting early in the spring and simply washing them off the underside of the leaves can help to avoid damage later and the need for pesticides.
Adult lace bugs are flattened and rectangular in shape measuring 1/8 to 1/4 inch long. The area behind the head and the wing covers form a broadened, lace-like body covering. The wings are light amber to transparent in color. Lace bugs leave behind spiny black spots of frass (excrement).
Adult azalea lace bug, Stephanitis pyrioides (Scott), and excrement. Photograph by James. L. Castner, University of Florida.
Lace bug nymphs are flat and oval in shape with spines projecting from their bodies in all directions. A lace bug nymph goes through five growth stages (instars) before becoming an adult. At each stage the nymph sheds its skin (molts) and these old skins often remain attached to the lower surface of infested leaves.
Nymphs of the azalea lace bug, Stephanitis pyrioides (Scott), with several cast skins and excrement. Photograph by James. L. Castner, University of Florida.
Azalea lace bug eggs are football-shaped and are transparent to cream colored. Lace bug eggs are found on the lower leaf surface, usually alongside or inserted into a leaf vein. Adult females secrete a varnish-like substance over the eggs that hardens into a scab-like protective covering.
Other plant species, such as lantana and sycamore, may have similar symptoms. But, realize that lace bugs are host specific. They feed on their favorite plant and won’t go to another plant species. However, the life cycle is similar. Be sure to clean up all the damaged leaves. That’s where the eggs will remain for the winter. Start next spring egg-free.
For more information go to: http://entomology.ifas.ufl.edu/creatures/orn/shrubs/azalea_lace_bug.htm
by Mark Tancig | Jul 11, 2019
An adult firefly showing off its characteristic beetle wings and bioluminescent abdomen. Credit: Art Farmer, Creative Commons.
Many of us have memories of warm summer nights watching fireflies. Some of us might have even chased and caught a few to put in mason jars for observation, fascinated by their glowing abdomens. Floridians have the best chance to see these unique insects, as we have more known species than any other state. Recently, I’ve had many folks say that they see less fireflies these days, which got me looking into how these creatures live and what researchers know about their numbers.
Fireflies are actually a type of beetle in the Lampyridae family. They go through complete metamorphosis, meaning their immature larvae look completely different than the adults. A very unique characteristic of the family is the ability to produce light, known as bioluminescence. They do this in a very efficient way, creating very little heat, through the reaction of luciferin and luciferase along with oxygen, some energy, and other compounds. These light-producing compounds serve a dual purpose, warding off predators and attracting mates. The larvae of all Lampyridae benefit from the offensive taste of the compounds while only some adult Lampyridae use bioluminescence to attract mates. Each species of firefly has specific patterns of flashes. Males have the showiest light displays while females use more conservative light shows to signal back to potential mates.
Firefly larvae taste bad to predators due to the compounds that produce light. Credit: Gerald J Lenhard, LSU, bugwood.org.
Larvae of fireflies live in the soil and feed on slugs, snails, earthworms, and other soft-bodied insects. The larvae develop in the soil during cooler months, preferring moist habitats, and emerge as adults in the late spring to early summer. Some species may emerge in the early spring. Adult fireflies feed on nectar and honeydew, though some females prey on smaller firefly species by fooling males close to them through light signaling. Adults with the ability to produce light are active at night, while non-bioluminescent adults are active during the day.
An adult firefly. Credit: Mirko Schoenitz, iNaturalist.org.
Entomologists specializing in fireflies have raised the concern that these classic summer-time insects are in decline. Reasons for the decline are associated with increased urbanization. Loss of suitable habitat and increased pesticide use, including broad-spectrum insecticides for home lawn insect control, negatively affect firefly larvae living in the soil. Researchers also point to urban light pollution as another cause. The ever-glowing night sky in populated areas, originating from house lights, ball fields, parking lots, and roadways, disturb firefly communication and reproduction.
UF/IFAS infographic about fireflies. Credit: UF/IFAS.
Homeowners can help fireflies by leaving small patches of unmanaged landscaped areas, such as along property lines, and only using insecticides when absolutely necessary. If pesticides are needed to control lawn and garden pests, the use of more selective, low-toxicity products is preferable. Turning off unnecessary outdoor lighting is another step homeowners can take to encourage firefly populations. Residents of homeowner associations can work together to minimize excess lighting community-wide, saving electricity and maybe even fireflies.
For more information on fireflies and best practices to control lawn and garden pests, contact your local county extension office.
