During the summer months, we can’t seem to get away from insects. Whether it’s a fly circling your food, those pesky aphids in your garden, or a mosquito out for blood, they make their presence known. But when winter rolls around and temperatures drop, they seem to disappear. But where do they go?
Unlike humans, insects are exothermic or cold blooded. They cannot regulate their own body temperature and must rely on the heat of the environment. Each insect species has its own developmental threshold, a temperature below which no development takes place. For many insects, that threshold is about 50 degrees Fahrenheit. This means that when temperatures drop below 50 degrees Fahrenheit, consecutively, the insect is not active, and no development is occurring. Typically, the warmer the temperature is (as long as it is above the development threshold), the more insect activity we see.
Insects may also enter a state called diapause, which is similar to hibernation. During diapause, an insect’s metabolism slows dramatically, and the insect stops feeding, growing, or reproducing. This allows the insect to survive through cold winter conditions, conserving energy until temperatures warm up again.
Another insect survival technique during the winter is migration. Many species of insects migrate to warmer climates to escape the cold. A well-known example of this is with the infamous Monarch butterfly migration. Monarchs migrate south to Mexico to overwinter and survive the cold weather. Some other insects migrate in smaller, less noticeable ways such as moving to different micro-climates. For example, beetle grubs may move down deep within the leaf litter to stay warm. Insects like lady beetles may congregate in large numbers inside homes, barns, or buildings during the winter.
Some insect species can produce glycerol, a type of anti-freeze, that prevents their body from freezing even when temperatures drop below freezing.
While many insects seem to disappear during the winter, they’re actually using their time wisely and although, cooler temperatures may slow down their activity, they won’t necessarily change insect populations drastically. Insects are well adapted for survival, and they are here to stay. They’re just enjoying a break until the warmth of spring brings them back!
Doodlebugs create pitfall traps in dry, sandy areas to lure unsuspecting ants. Their “doodles” in the sand are visible as well. Photo credit: Carrie Stevenson, UF IFAS Extension
It’s been years since I ran across doodlebugs. But when I saw a stretch of their pitfall traps at a campsite near Coldwater Creek in MIlton, I knew it was time to write about them. Lore says their silly name came from Southern kids like me, who watched the larvae drag their bodies around in the sand, leaving patterns (or doodles) etched behind them. These insects have long fascinated children and creative writers, with some of my favorite authors–Twain, Steinbeck, Thoreau–referencing doodlebugs in their books.
Doodlebug larvae are pretty terrifying, with those giant killer mandibles. Photo credit: UF IFAS
Doodlebugs, aka ant lions (Myrmeleon immaculatus—although we have 22 species in Florida!), are fascinating little insects that prey upon ants by creating slippery funnels in the sand. They wait underground below the funnel opening as unsuspecting ants march along the surface and slide down in the ensuing “mini avalanche.” If an ant or other prey item manages to get away, the ant lion can sling sand at it to try and knock it back down into the pit. Doodlebug larvae are the stuff of cartoon nightmares. They possess a pair of giant clawed mandibles, capable of grabbing and injecting prey with a toxin. The poison paralyzes the victim and contains digestive fluids which liquify its insides. At this point, the ant lion goes in for the kill by sucking out the prey’s juices through its deadly mandibles.
An adult doodlebug/ant lion bears no resemblance to its larval stage! Photo credit: Campbell Vaughn, UGA
Ant lions may stay in this frightening larval stage for up to 3 years. After this they undergo metamorphosis, spending 3 weeks in a cocoon. As adults, their transformation is dramatic; they are closely related to lacewings and dobsonflies, with long, thin bodies and large translucent wings.
A doodlebug captures its prey. Photo credit: UF IFAS
As kids, we always found doodlebugs under my best friend’s treehouse. In Milton, they were in a sandy area beneath a cabin roof overhang. These dry, protected sand areas are their preferred habitat and the best place to find them. We used to stick pine needles down into the openings, and watch as a flutter of insect mouthparts tried to grab it from us. Because of their fascinating life cycle and dramatic hunting technique, doodlebugs can be a captivating addition to a science classroom. In fact, there’s a reference to doodlebugs on the NASA website, due to an Apollo 16 astronaut’s mention of them. When landing on the moon, the craters reminded Charlie Duke of doodlebug pits, prompting him to recite an old children’s rhyme, “Doodlebug, doodlebug, are you at home?”
The Great Southeast Pollinator Census began in Georgia in 2019 with the goals of increased pollinator habitat, teaching the public the importance of insects, and providing useful data to researchers. 2024 is the first year for Florida to be included and we want to support this project with strong participation. View the webinar from the Northwest District Horticulture Team that teaches how to identify pollinators as well as how to collect and submit data for the 2024 Great Southeast Pollinator Census.
You may recognize the arrival of summer because of the intense buzzing sound coming from the trees. It can last all day long, with changes in the pitch and pattern of the screaming.
Dusk-calling cicada, Tibicen auletes (Germar). Total length (head to tips of forewings) is 64 mm (about 2 1/2 inches). Photograph by Lyle J. Buss, University of Florida.
Cicadas are large (3/4” – 2 ½”) winged insects with stocky bodies and bulging eyes. They spend the vast majority of their lives underground, emerging in massive numbers for just a few weeks to mate and lay eggs. This behavior often earns them the name “locusts,” which entomologically they are not.
In much of the eastern United States, periodical cicada (Magicicada spp.) broods rise up out of the ground every 13 or 17 years. In the summer of 2024, two different broods (one group of 13-year cicadas and one group of 17-year cicadas) will arrive at the same time across 16 states. The closest to us will be mid-lower Alabama. Approximately one trillion insects are anticipated. This only happens once every 221 years.
By emerging in large numbers, the cicadas are able to reduce the potential of being eaten by predators. Though many will be lost to birds and killer wasps, enough will survive to be able to reproduce.
Unlike the broods of periodical cicadas, populations of Florida’s 19 cicada species produce adults every year. However, the nymphs still spend several years developing underground. The nymphs use their piercing-sucking mouthparts to feed on the xylem sap in the roots of trees. The feeding can weaken already stressed trees. Most trees tolerate the damage quite well. After gaining enough nutrients, the nymphs wait for the soil to warm enough (approximately 64° F. at six inches deep) before crawling out of the ground, climbing up the tree trunk, and molting into adults with wings. You can often find the empty shed exoskeleton still hanging on the tree trunk.
The adult male spends all day being as loud as possible in order to attract the girls. Each species has its own song. Large numbers of insects create more noise. Male cicadas have a pair of tymbals located on the sides of their abdomen. Tymbals are corrugated regions of the cicada’s exoskeleton that can be vibrated so rapidly that the clicking sound becomes a high-pitched buzz. Cicadas with the best abs get the girls and reminds all the humans that summer is here.
Cicada (Tibicen sp.) escaping its nymphal skeleton. The cast skeleton will remain attached to the tree. Once free, the adult will expand its wings, darken, and fly away. Photograph by Lyle J. Buss, University of Florida.
They’ve mostly all moved away for now, but every winter and early spring the office gets questions about tiny beetles in homes. These beetles are small with spotty color patterns. The answer is carpet beetles. Carpet may be in their name, but it may not be their favorite spot. Carpet beetles feed on a lot of the same things as clothes moths such as wool, felt, and fur because these materials contain keratin. And their feeding damage is often mistaken for that of clothes moths.
Varied carpet beetle adult. Photo Credit: Lyle J. Buss, University of Florida/IFAS
Adult carpet beetles are between 1/16 to 1/8-inch in length. They are oval-shaped and range in color from black to various patterns of white, brown, yellow, and orange. The majority of samples we see are black and white mottled. The adults are often found on windowsills and window stools in the springtime. The larvae conduct all the damage to fabrics and other materials, while the adults stick to feeding on flower pollen. The evidence of feeding can be seen by threadbare spots and irregular holes. Blankets and clothes in storage and carpeted areas under furniture are preferred because they are undisturbed.
As with most insect pests, prevention is the best control for carpet beetles. In addition to feeding on fabrics and material, larvae feed on dust, lint, and animal hair. Frequent cleaning of floors and vacuuming of rugs and carpets eliminates most of the food supply. Stored blankets, clothes, and rugs should be periodically cleaned, brushed, and or sunned. Moth balls can be used at labeled rates but should not be the sole means of control.
A typical crane fly on the outside of a building. Photo credit: Carrie Stevenson, UF IFAS Extension
All my life, I’ve known them as mosquito hawks. Built like extra-large, spindly-legged versions of mosquitoes, they look a bit intimidating. However, growing up we were told they were harmless and actually fed solely on mosquitoes. In the days before Google, I just accepted it as fact and was glad to see them around.
In early March, there was a bit of an invasion of these insects. I started seeing them everywhere outdoors and inside my office building. They are slow movers, bouncing in the air more than flying. After several days of seeing them everywhere, though, they pretty much disappeared.
Several crane flies appear to have met their demise inside my office building. Photo credit: Carrie Stevenson, UF IFAS Extension
Like much folk wisdom accrued through my life, the story of the mosquito hawk is not totally true. They are harmless, that much is correct. While many people do know them as mosquito hawks, the accepted common name is the crane fly. Crane flies come in a wide variety of sizes and colors, ranging as some of the smallest and largest species in the fly Order, Diptera. Their diversity is rather mind-blowing, with the Family Tipulidae including about 15,000 species of crane flies worldwide.
Crane fly larvae live in aquatic environments and feed on decaying plant material. Photo credit: North Carolina State University
As for being voracious predators of mosquitoes, we have no such luck. Crane flies barely eat at all, because their adult life span is as short as those two weeks I recently noticed them around. They spend most of their lives as aquatic larvae, living in streams, pond edges, and rotting vegetation. Adults do not have the right mouth anatomy to eat other insect prey, instead drinking only by sponging up water in dew form or taking nectar from plants. Their primary purpose in adulthood is to complete the mating process. Females lay eggs near water, hence the location as larvae. After this hedonistic spring break experience of adult life, they die.
Crane flies, in both larval and adult forms, are popular snacks for other wildlife. The adults are easy targets for birds and bats. The larvae, which in some species are as large as a pinky finger, are tasty morsels for fish and amphibians. During their larval existence, crane flies ingest debris, helping with the decomposition process and filtering the water bodies they live in. Despite their short life span, crane flies make an outsized contribution to the food web.
