This tomato hornworm is being parasitized by beneficial wasps. Photo credit: Henry Crenshaw
Why would anyone allow dozens of wasps to thrive in their garden? Why would they let caterpillars keep moving through their pepper bushes? Don’t they know you can spray for that?
As Extension agents, one of the tenets we “preach” in gardening is the concept of Integrated Pest Management (IPM). This technique involves a series of insect control measures that begin with the “least toxic” method of control, using chemicals as a last resort. One of those least toxic measures is “biological control”, in which a natural predator or parasite is recognized and allowed to remove a pest insect naturally. It is important to be able to recognize some of the more common garden predators and parasites. Many times these insects look strange or dangerous, and they are mistaken for pests and killed.
One such beneficial insect to the home gardener is the braconid wasp (Cotesia congregatus). Most people shudder at the mention of wasps, but these tiny (1/8 inch long), mostly transparent wasps are of no danger to humans. Quite the opposite–they are an excellent addition to gardens, especially if you are growing tomatoes or peppers. One of the major pests to these favorite vegetables is the tomato hornworm (Manduca quinquemaculata), a fat green and white-striped caterpillar.
The beneficial wasp can control hornworms because females lay eggs under the caterpillar’s skin, after which the eggs hatch and larvae feed on the hornworm. After eating through the caterpillar, they form dozens of tiny white cocoons on the caterpillar’s skin. The tomato hornworm is rendered weak and near death, and the vegetable crop is saved.
If you happen to find a tomato hornworm covered in these small oval cocoons, consider yourself lucky. Let the process continue, allowing the new generation of beneficial wasps to hatch and continue their life cycle. They will control any future hornworms in your garden, and the whole process is fascinating to watch!
For questions on integrated pest management, beneficial insects, or growing peppers and tomatoes, call your local County Extension office.
A Florida Master Naturalist Uplands class visits the highest point in Florida, located in Walton County. Photo credit: Carrie Stevenson, UF IFAS Extension
For many Floridians, gardening is a window into learning the cycles of the natural world. Understanding pollination, distinguishing beneficial insects from harmful ones, creating compost, or knowing what time of year to apply iron supplements are important for a gardener to be successful. While we have our share of campers, hikers, and kayakers, over the years Extension agents have found that some of our best Master Naturalist students are those with fond memories of farming or gardening as children or adults.
If you have always been fascinated by the natural world and how plants, animals, and people interact, you might be a perfect candidate for the Master Naturalist program. Offered periodically in almost every county in Florida, this adult educational course combines classroom sessions with field instruction, typically over a six-week period. At graduation, students present an original project, which may vary from creating an exhibit, a children’s book, or even an environmental non-profit organization.
Master Naturalist students vary in backgrounds from retired military and teachers to park rangers and college students. Many Master Gardeners find the courses a helpful addition to their training, and utilize their newly gained knowledge when working with clientele. At completion, students receive an official Florida Master Naturalist certificate, pin, and patch.
The traditional 40-hour courses cover Upland, Coastal, and Freshwater Wetland habitats, while the newer “special topics” cover Conservation Science, Environmental Interpretation, Habitat Evaluation, and Wildlife Monitoring. A new “restoration” series has begun with the Coastal Restoration class, which kicked off in Escambia and Santa Rosa counties and is currently being taught in Bay. Extension agents will be offering several classes in the Panhandle this fall—check out the FMNP registration site to see when a class will be offered near you!
Ah, the oft-ignored pine tree. They are so ubiquitous throughout the southeast, that many people consider them undesirable in a landscape. Having grown up near the “Pine Belt” of Mississippi, I figured I knew plenty about them, but this week I learned something new. While on a field tour with local foresters in the business of loblolly and longleaf pine farming, they introduced me to the pine tip moth. These insects can wreak havoc on valuable young pine trees.
Dead branch tip and needle damage caused by pine tip moths. Photo credit: Carrie Stevenson, UF IFAS Extension
Hollow space in pine tree branch created by pine tip moth. Photo credit: Carrie Stevenson, UF IFAS Extension
Female pine tip moths lay eggs on the growing end of a pine branch—particularly young, healthy loblolly and shortleaf (longleaf is rarely affected). When the eggs hatch 5-30 days later, the larvae start feeding. They tunnel into the shoot and bud of the pines, feeding on the tissue and burrowing a hollow cavity for several weeks. The larvae then pupate inside the space until becoming adult moths, exiting from the hole they created. The cycle restarts, with more adult moths, eggs and larvae.
Adult Nantucket pine tip moth Rhyacionia frustrana (Comstock). Photograph by James A. Richmond, USDA Forest Service, www.Forestryimages.org.
Two insect species are most common in our area; the subtropical pine tip moth (Rhyacionia subtropica) and Nantucket pine tip moth (Rhyacionia frustrana). The moths are reddish copper in color, small (1/2” wingspan and 1/4” body length) and active at night. Caterpillar larvae have black heads and start out with off-white bodies, but change in color to brown and orange as they age.
While this insect activity typically does not kill the tree, it does cause some die-off of terminal needles and branches. In extreme cases, it can cause tree death. Moths prefer younger trees and rarely affect pines taller than 15 feet.
If you see a cluster of dead needles at the ends of young pine branches of your property, you can easily snap off the dead tip. You will likely find the hollow space formed by the larvae, which in spring may still contain the insect. Treatment in a home landscape can managed by hand removal of infested shoots, but those in the commercial forestry business may need to install traps and consider insecticidal management.
Visit the UF School of Forest Resources and Conservation website for more information.
The swollen base and smooth gray bark of the swamp blackgum are identifying characteristics in wetlands. Photo credit: Carrie Stevenson, UF IFAS Extension
In the river swamps of northwest Florida, the first tree to come to mind is typically the cypress. The “knees” protruding from the water are eye-catching and somewhat mysterious. Sweet bay magnolia is an easily recognizable species as well, with its silvery leaves twisting in the wind. The sweet bay (Magnolia virginiana) is a relative of the Southern magnolia (Magnolia grandiflora) in many of our yards, but its buds and leaves are smaller and it is found most often in very wet soils.
However, the often-unsung trees of the swamps are the tupelo and blackgum trees, including three species of Nyssa that go by a variety of overlapping common names. In the western Panhandle, one is most likely to see a swamp tupelo/swamp blackgum (Nyssa sylvatica var. biflora). The trees are tall—60-100’ at maturity—and have unremarkable elliptical green leaves. However, those leaves turn a lovely shade of red in the fall before dropping in the winter. Their most distinguishing characteristic year-round–but especially in the winter–is its swollen lower trunk, which expands at the base to twice or three times the size of the remaining trunk. These buttresses, also found on bays (more subtly) and cypress (along with knees), are an adaptation to stabilizing a tree growing in large pools of wet, loose soil or standing water.
A young blackgum tree in full fall color. Photo credit: UF IFAS Extension
The swamp tupelo has two more relatives in the region, water tupelo (Nyssa aquatica) and Ogeechee lime/tupelo (Nyssa ogeche), both with hanging edible (but tart) fruit. In the early days of William Bartram’s explorations of Florida, explorers used the acidic Ogeechee lime as a citrus substitute. Typically found in a narrower range from Leon County east to southeast Georgia, the Ogeechee lime is the nectar source for the famous and prized multi-million dollar tupelo honey industry.
Blackgum or tupelo trees (missing the “swamp” in front of their common name—aka Nyssa sylvatica) are actually excellent landscape trees that can thrive in home landscapes. Like their swamp cousins, the trees perform well in slightly acidic and moist soil, although they can thrive even in the disturbed, clay-based soils found in many residential developments. Blackgums can grow in full sun or shade, are highly drought tolerant, and can even handle some salt exposure. Their showy fall color is a nice addition to many landscapes, and the fruit are an excellent source of nutrition for native wildlife.