Fall webworms in a Tennessee forest. Photo credit: UF IFAS Extension
Have you ever noticed the big knots of webbing in some trees this time of year? They’re usually sort of a brown-pink hue, much too big for a spider but not really tightly wound enough to be a nest or cocoon.
A close-up of the fall webworm tent reveals dozens of tiny caterpillars and skeletonized leaves. Photo credit: Carrie Stevenson, UF IFAS Extension
What you’re seeing actually is a cocoon of sorts—a big shared one created by hundreds of larval fall webworms (Hyphantria cunea). This common name is a bit of a misnomer. The webbing—often referred to as a tent—is built in late summer, not fall, and these are caterpillars, not worms. But I suppose it gets the idea across!
On a recent hike, I saw webbing up close, so I was able to really investigate the caterpillars inside. They are quite small, and will undergo up to five molting stages, or instars, before adulthood. Upon transformation, they will become white or speckled moths. Fall webworms are native to the entirety of the United States—in the northern end of their range the moths will be solid white, whereas further south they will have darker spots on their wings. Due to accidental introduction, fall webworms are invasive throughout Europe and portions of Asia.
Adult fall webworm, with spots on white, which is typical for members of this species from the southern part of its range. Photo credit: Lyle Buss, UF
Host plants include a wide range of more than 80 deciduous hardwood species, allowing a broader spectrum of places for the caterpillars to undergo their various larval phases. During their months in the “tent”, the larvae feed on and skeletonize the leaves encapsulated within their webbing. This causes damage to the leaves, but results in no permanent issues to the trees—being late summer and fall during their tenure, the trees eventually lose their leaves anyway.
While the tents are a bit unsightly, controlling the caterpillars or removing the webs is unnecessary. Once they’ve reached their final caterpillar stage, they’ll hide out in tree bark and leaf litter on the ground until metamorphosizing into moths the following spring. Adult moths mate and lay eggs in the late spring and summer, starting the cycle all over again.
A cicada killer burrow at the Escambia County Extension Office. Photo credit: Carrie Stevenson, UF IFAS Extension
The other day, our Horticulture agent, Beth Bolles, called me over to point out something of interest. Along the sidewalk between our buildings was a sandy burrow that looked like a cross between a fire ant mound and a crawfish burrow. “People ask me about these all the time—you may want to write about them,” she said. Sure enough, just a couple days later I was tagged in a Facebook photo asking if I knew what this weird sandy mound was.
An up-close photo of a cicada killer brought into our office for identification. Photo credit: Beth Bolles, UF IFAS Extension
What Beth pointed out was the burrow of a cicada killer (Sphecius speciosus) wasp, also called the great ground hornet. Cicada killers are large (among the largest in the country, at 1.5-2” long) ground-dwelling wasps that use cicadas for an important part of their life cycle. They can fly, but I have observed them crawling through low weeds and grass. They have black bodies and wings with brilliant yellow stripes on their abdomens, and adults feed on flower nectar.
These wasps’ reproductive cycle is rather fascinating. After males and females emerge from the soil in the summer, they mate while in flight. Females then dig the burrows, using their front legs to scrape soil out of the ground and kick it out with their hind legs. Burrows may be up to 4 feet deep, with branches and larger cells.
A female cicada killer with her cicada prey. Photo credit: North Carolina State University Extension
Future moms then seek out cicadas, which they sting and paralyze on the leg. The wasps drag cicadas on their backs and into their underground burrows. They place 1-4 cicadas in each cell, depending on insect size. Once this task is completed, the females lay eggs—one into each cicada body. The sex of their offspring can be determined by placement, with the more substantial cicadas implanted with future females, who will need the extra energy. Female cicada killers have been observed to share their burrows with as many as 3 other wasps.
While female wasps stay busy with reproduction and burrowing, the males primarily serve roles of protection and competition for mates. Male cicada killers are known to “invade personal space” of humans by hovering at eye level, and can seem aggressive. However, they are harmless—only the females have stingers!
Green anole on a fence post. Photo credit: Dr. Steve A. Johnson, UF
There’s plenty of animals you might call “cute”, but lizards usually aren’t among them. However, I’d take exception to that premise when discussing the green anole (Anolis carolinensis). With big blue eyes, brilliant green skin, and flirty males doing push-ups and flexing their dewlaps (the pink throat fan) at you, these little reptiles are more endearing than most.
A green anole–with a slightly forked tail–poses on a deck chair. Photo credit: Carrie Stevenson, UF IFAS Extension
Native to Florida and the deep South, they are competent crawlers, prowlers, and predators. I see them frequently on my office building’s outer stucco walls, running along fences, or skittering up trees. They feed on beetles, termites, ants, worms, spiders, and more. Called the “American chameleon” by some, they possess excellent camouflage, changing their skin rapidly from green to dull brown depending on their backgrounds.
Over the last few years, I—and many biologists—have been concerned about the health of their population. As the invasive Cuban brown anole successfully gained a foothold in north Florida, I saw fewer green anoles and many more of the browns. It has seemed that the greens were losing ground. The invasive species can outcompete the native by eating the green anoles’ young and eggs.
Male brown anole on a tree. Photo credit: Dr. Steve A. Johnson, UF
A recent study by a UF PhD candidate found another explanation for why Floridians have seen more brown anoles than green. His study found that the two species have found a way to coexist—the green anoles are moving further up the canopy (an average of 17x higher!), while browns are staying closer to ground level. The green anoles thrive in more natural areas, whereas the brown anoles do well in lower level urban surroundings.
Interestingly, this summer I’ve noticed a resurgence in green anoles and have rarely seen brown ones. I am wondering if our snow days knocked the tropical brown anole populations back, enabling the more temperate greens to recover. Time will tell if the greens have regained their advantage or if it’s only temporary.
A tiny juvenile praying mantis stalks prey on a gloriosa lily. Photo credit: Carrie Stevenson, UF IFAS Extension
The gloriosa lilies have been in full glory, so to speak, in our garden at the Extension office the last few weeks. While photographing them, I noticed a tiny visitor hidden in plain sight among the flower’s frilly petals and stamen. A bright green juvenile praying mantis, no more than an inch long and the same shade of green as the plant, stood still directly in front of me.
A Larger Florida Mantis perches on blazing star flowers in Sarasota. Photo credit: chaseyb via iNaturalist
Praying mantids are often recognizable and well-known due to their interesting body shape and posture. They have other wild features, too, like gigantic folding “raptorial” (grasping/predatory) front legs and the ability to swivel their big-eyed, alien heads 180°. The large European mantid’s Latin name, Mantis religiosa, comes from the insect’s posture when hunting. It sits or stands with its forelegs folded up as if in prayer, before deploying them rapidly for a meal. All mantid species are ambush predators, capturing prey by sitting in wait, camouflaged in color and shape. They’ve even been observed swaying gently to appear like leaves in the breeze. But when they spring to attack, they are deadly accurate.
The charismatic praying mantis, in stealth attack position. Photo credit: University of Wisconsin Extension
The insects are known for their infamous (but rare in the wild) post-mating male beheading. Mantids are not alone in that cannibalistic behavior—many insects and spiders exhibit this conduct to boost the energy of females as they produce the next generation. Most mantid species are tropical, but of the 2400 known worldwide, only about 20 live in the United States (11 in Florida).
Mantids are considered natural pest control in a garden, although they are generalists and will prey on both beneficial and pest insects. With those spiky front legs raised in the air, they drop down and grasp prey ranging in size from aphids to—rarely—hummingbirds. Their effective predatory behavior doesn’t make them immune from becoming prey themselves, however. Mantids are a food source for many species, including bats, birds, spiders, and fish.
A male bluebird perches on his nest box at the Extension office. Photo credit: Carrie Stevenson, UF IFAS Extension
“Don’t fly, Mister bluebird, I’m just walkin’ down the road. Early morning sunshine, tell me all I need to know.” These lyrics from the Allman Brothers’ song, “Blue Sky” always come to mind when I step outside our office building in the springtime. We have several bluebird houses installed on the Extension grounds, and birds have been busily building nests the last several weeks. Despite my attempts to admire from a safe distance, I inevitably disturb them and they fly off.
The Eastern Bluebird (Siala sialis) is a native species of cavity nesting bird, which covers territory from central Canada all the way south to Texas and coastal Florida. The United States is home to two other native bluebirds, the Mountain bluebird (S. currucoides), residing in high plains from Alaska to the mountain southwest, and Western bluebird (S. mexicana), which lives in drier evergreen forests on the west coast, from southern Canada to Baja Mexico. In comparison photos, the bluebird species have redder bellies on the east coast and are progressively bluer as you move west.
American bluebird species comparison. Courtesy Cornell Lab of Ornithology
A pair of bluebirds perched atop our office building. A grayer-feathered (likely female) bird can be seen on the left, near the deeper blue male on the right. Photo credit: Carrie Stevenson, UF IFAS Extension
Bluebirds’ striking color patterns make them a favorite of amateur birdwatchers and one of the easiest birds to identify in the field. Their brilliant blue is a trick of the eye, though—in reality, birds are unable to produce blue feathers. Flamingos and roseate spoonbills produce genuine pink feathers using pigments from their food (like shrimp), but bluebirds are actually gray. As described by Smithsonian wildlife biologist Scott Sillett, the blue is a “structural color” formed by the angles of sunlight and refraction from keratin, creating the illusion of a brilliant blue. I’ve always thought bluebirds seemed brighter blue on sunny, blue-sky days—turns out they probably are!
Like bluebirds, numerous native bird species are cavity-nesters. Photo credit: Carrie Stevenson, UF IFAS Extension
Bluebirds have overcome numerous threats to their populations over the last few hundred years in the United States. From habitat loss, fire ants (which attack nestlings), pesticides, and competition from introduced house sparrows and European starlings, bluebirds struggled for quite some time. Thankfully, their populations are now actually increasing and they are a “species of least concern.”
I noted about a year ago that someone in my neighborhood installed half a dozen bluebird boxes in our neighborhood park, and I’m betting that trend is multiplied exponentially around the country. Eastern bluebirds are a species of thrush, and are just one of many species that might utilize a nest box. In the wild, they are secondary cavity nesters. This means they wait for a primary cavity nester, like a woodpecker, to create a hole, then move in after it’s been abandoned. So, they are quite content to move into a prefabricated home built by humans.
A bluebird forages for insects on the ground. Photo credit: Carrie Stevenson, UF IFAS Extension
From ancient Chinese, Russian, and Native American mythology to folklore and music of the deep South, bluebirds hold a special place in the human imagination. The song and phrase “bluebird of happiness” reflects their cheery appearance and simple joy. In a quick online search of bluebird references in popular culture, I found more than 25 in the last 100 years. Something about the impossibility of a brilliant blue little bird on a spring day just feels uplifting and joyful. Even in the wistful song from the Wizard of Oz, Dorothy sings, “Somewhere over the rainbow, bluebirds fly.”
