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 Matt Lollar | Apr 23, 2020
I was recently sent some pictures of some unusual growths on pecan tree leaves. At first glance, the growths reminded me of the galls caused by small wasps that lay their eggs on oak leaves. However, after a little searching it became apparent this wasn’t the case. These galls were caused by the feeding of an aphid-like insect known as phylloxera.
Leaf galls caused by pecan phylloxera. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
The feeding from the phylloxera causes the young leaf tissue to become distorted and form a gall that encloses this female insect called a “stem mother”. These insects are rarely seen, but the hatch from over-wintering eggs in March/April just after budbreak. Once hatched, these “stem mothers” crawl to the new leaves and begin feeding. Once the gall forms, they start to lay eggs inside the gall. The eggs hatch inside the gall and the young phylloxera begin to feed inside the gall and the gall enlarges. The matured insects break out of the gall in May and some will crawl to new spots on the leaves to feed and produce more galls.
Pecan stem damage from phylloxera. Photo Credit: University of Georgia
There are two common species of phylloxera that infect the leaves. The Pecan Leaf Phylloxera seems to prefer young trees and the Southern Pecan Leaf Phylloxera prefers older trees. The damage from each of these insects is nearly indistinguishable. Damage from these insects is usually not severe and merely an aesthetic issue.
Once the damage is discovered on a tree, it is too late to control the current year’s infestation. There are currently no effective methods for control of phylloxera in home gardens. Soil drench applications witha product containing imidacloprid have been limited in their effectiveness.
by Ray Bodrey | Apr 8, 2020
Spring has arrived and so have the insects. Caterpillars are crawling around and one possesses a unique appetite.
Neodiprion spp. is the most common defoliating insect group affecting pine trees. In all, there are 35 species that are native to the U.S. and Canada. The redheaded pine sawfly, Neodiprion lecontei, is the primary species found in the Florida Panhandle.
Adult sawflies can be as large as 1/3 of an inch in length. The female can be two-thirds larger than the male and are mostly black with a reddish-brown head, with occasional white coloration on the sides of the abdomen.
Mature larvae of the redheaded pine sawfly. Credit: Patty Dunlap, Gulf County Master Gardener.
The ovipositor, the tube-like organ used for laying eggs, is saw-like, hence the common name. During the fall, females make slits in pine needles and deposit individual eggs, up to 120 eggs at a time. The eggs are shiny, translucent and white-hued. Mature larvae (caterpillars), as seen in the accompanying photo, are yellow-green, emerge in the spring and feast on pine needles. After weeks of feeding on needles, the mature larvae drop to the ground. The cocoon, a reddish-brown, thin walled cylinder, is spun in the upper layer of the soil horizon or in the leaf litter; this is called the pupae stage. The pupae overwinter, and adults emerge from the cocoon in the spring of the following year.
Mature larvae are attracted to young, open growing pine stands. Pine is the preferred host, but cedar and fir, where native, are secondary food sources. Neodiprion lecontei is an important defoliator of commercially grown pine, as the preferred feeding conditions for sawfly larvae are enhanced in monocultures of shortleaf, loblolly, and slash pine, all of which are commonly cultivated in the southern United States. Defoliation can kill or slow the growth of pine trees as well as predispose trees to other insects or disease.
Are there control methods? Yes, biological control is a major factor, as natural enemies are numerous. Disease, viruses and predators help regulate population control. For small scale control, physically removing eggs or larvae is key. Again, most infestations occur on younger tree plantings, so they’ll be in reach. Be sure to scout young pines for signs of infestation. Horticultural soaps and oils are effective chemical controls, if needed.
For more information, contact your local county extension office.
Supporting information for this article can be found in the UF/IFAS Extension EDIS publication, “Redheaded Pine Sawfly Neodiprion lecontei” by Sara DeBerry: https://edis.ifas.ufl.edu/pdffiles/IN/IN88200.pdf
UF/IFAS Extension is an Equal Opportunity Institution.
by Sheila Dunning | Mar 20, 2020
Until recently, rainfall has been plentiful. That’s great for the water table and preparing plants to wake up for spring. But, insects are also stirring. Bugs are affected by rain in many ways. When water is plentiful, they can grow faster, reproduce sooner and travel farther. Combine that with the fact that the insects’ homes are being flooded out and their normal food sources are displaced; and where do you think they are headed? Yes, into your house. Four bugs you can anticipate seeing after rain events include cockroaches, sowbugs, ants and centipedes.
American Cockroach
Photo by: J.L. Castner
UF/IFAS
Roaches tend to live in places that flood easily, especially this time of year. To survive the cold nights, cockroaches need to find a warm place to rest. Typically those places would be drains, pipes, sewers, along foundations and in crawl spaces. But, when it rains, these locations are often flooded, forcing cockroaches to scurry for their lives to avoid drowning. A crack in weather stripping or window caulking makes a quick hideaway. Once inside, they may decide to stay. Frequent rainy days create the lingering humidity that makes all kinds of places more livable for roaches.
Sowbugs and his cousin, the pillbug, are very small, pill-shaped pests with multiple legs and a series of shell-like plates. Often referred to as roly-polys, these creatures are actually a form of land
Sowbug
Photo by: J.L. Castner UF/IFAS
crustacean related to lobsters, crabs, and crayfish. The sowbug’s breathing tubes require moisture to function properly, so they must stay near water. Typically this fact restricts the sowbug to living in moist soil or sand. Ending up inside a building is normally a terminal condition for them. However, due to the moisture left in the air after a rain event, sowbugs that seek refuge inside are able to survive for longer periods of time. Given the opportunity, sowbugs will reproduce indoors. If they have decaying organic material to feed on, they may stick around even longer; having time to create a multi-generational infestation.
Carpenter Ant
Photo by: J.L.Castner
UF/IFAS
Ants are never too far away. They usually build their colonies in the soil near convenient sources of food and shelter. Being in the ground puts ant colonies at great risk for flooding out, even with short periods of rainfall. When this happens, ants are forces to find higher, drier ground quickly or risk being washed away. What better place than a house? Once inside, the ants get back to work looking for food and building the colony. Expect to see ants around kitchen sinks, on window sills and working their way into cupboards and pantry areas during and after a heavy rain. Unfortunately, if they find all the elements needed to make their home, the ants will be very reluctant to go back outside.
Centipede Photo by: J.L. Castner UF/IFAS
Like the other pests mentioned, centipedes are attracted to humid environments. But, centipedes are active hunting carnivores. They like to feed on roaches, sowbugs and ants. So, they follow them into the house, a well-stocked hunting ground. Centipedes typically only hunt late at night, but in dark areas they can hunt day and night. Finding centipedes if most likely an indication of another pest infestation.
These rain-displaced pests may need some help from a pest control product and/or operator to be discouraged from staying inside. We need the rain. But, keep a close watch for the unwanted visitors.
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 Molly Jameson | Feb 27, 2020
Larva of the granulate cutworm (Feltia subterranea). Photo by John L. Capinera, Entomology and Nematology Department, University of Florida.
One of the biggest predicaments growing vegetables in my backyard garden is dealing with cutworms. Cutworms are a type of nocturnal moth larvae that feed by wrapping themselves around seedling stems at the soil surface. They then cut the stem of the seedling in two – as if Edward Scissorhands dropped by for a visit – killing the plant. There are multiple species, but one of the most common in Florida is the granulate cutworm (Feltia subterranea). They are distributed most frequently in the tropics but can occur as far north as Southern Canada and regularly occur in the Southeastern United States.
My plan was to install cutworm collars the next morning. But that night, cutworms chewed through the stem of this tomato seedling in two locations. Photo by Molly Jameson.
Since cutworms feed at nighttime it is particularly frustrating, as you will find plants which appeared fine in the evening destroyed by morning. What’s even more frustrating is they feed in multiple seasons on a very wide range of crops, including tomatoes, beans, corn, eggplant, lettuce, peppers, watermelon, celery, broccoli, cabbage, and kale, to name a few. This fall and winter, I even found they had attacked my carrots and onions, which I thought would be more resistant.
One approach a backyard gardener can take in combatting cutworms is to use physical barriers. Netting or row cover can help prevent mature moths from ovipositing their eggs. But if you already have larvae invading, this technique will be ineffective.
For plants with stems less than pencil-width thick, make cutworm collars to help protect young seedlings from attack. Photo by Molly Jameson.
Plants with stems that are less than pencil-width thick are most susceptible to cutworm damage. A useful tactic is to make what are called “cutworm collars.” Surround individual seedlings with toilet paper rolls, taking care not to break fragile stems as you position the rolls over the plants. Materials such as soda cans or cereal boxes can be cut into strips to encircle seedlings if toilet paper rolls are too small to safely fit over the plant. Try to extend the cardboard two inches below and two inches above the soil surface. In this way, the cardboard acts as a barrier, and can help keep cutworms from accessing the stems.
Unfortunately, if cutworms are already hiding in soil close to the plants, the collars might not be effective. Another technique to try, especially if cutworms are already present, is the toothpick method. Place two toothpicks vertically in the soil on each side of the stem. They should be right up against the stem. In this manner, the toothpicks should prevent the cutworm from wrapping around the stem to chew through.
This onion start was given a moonlit haircut by feasting cutworms. If you are lucky, you may be able to find the culprit by digging around the soil adjacent to the afflicted plant. Photo by Molly Jameson.
It can also be helpful to scout your garden for cutworms. Carefully dig one to two inches into the soil near afflicted seedlings. The caterpillars are small, growing from a few millimeters up to less than two inches in length, but tend to stay curled up near the soil surface within about a foot radius of their vegetative victims. Crush any cutworms you find, or for the squeamish, simply drop the cutworms into soapy water.
Applying the bacterial insecticide Bacillus thuringiensis var. kurstaki (Bt for short) may help control cutworms but be sure to apply in the evenings and not before a rainfall or irrigation event, as sunlight and water render Bt useless. And keep in mind, cutworms must digest Bt to be effective, so you may need to apply multiple applications. As with any insecticide, always remember to follow the directions on the label. Once seedling stems grow larger than pencil-width, they should be safe from cutworm mayhem. That is… until the next garden vandal comes along!
To learn more, visit the University of Florida Entomology and Nematology Department’s Featured Creatures page about the granulate cutworm (http://entnemdept.ufl.edu/creatures/veg/granulate_cutworm.htm). You can also search for cutworms on the UF/IFAS EDIS website to learn about additional cutworm species found in our area (http://edis.ifas.ufl.edu/).
