DRAGONFLIES, FIREFLIES, WASPS, BEES, HORNETS AND OTHER FLYING INSECTS

FLYING INSECTS

Most flying insects move their wings in long, sweeping strokes (140 to 165 degrees) at roughly 200 beats a second. Bees, wasps and hornets (Order Hymenoptera) have two sets of wings. Flies (Order Diptera) have only one set.

Carnivorous flying insects employ several hunting strategies, including: 1) “hawking,” hunting while in flight using their speed and maneuverability to chase down prey; 2) “sallying,” in which the hunter waits patiently on a perch and then darts out suddenly to grab prey; 3) “gleaning,” hoovering or flying around a spot and picking prey off the ground or vegetation.

With wings beating at 150 times per second in a U-shaped beat, a common blowfly can hoover in the air and fly with exceptional dexterity. It can go from straight-line flight and turn 90 degrees in under 50 milliseconds — a maneuver that would rip apart even the most advanced fighter planes. Ron Fearing, a professor of electrical engineering at Berkeley, who has studied the flight of the insect told National Geographic, “The flying wing is driven by 20 muscles, some of which only fires every forth wing beat, and all you can do is wonder, what on earth just happened there. Some things are just too mysterious and complicated to be able to replicate.”

Fearing has created robot about the size of an insect that is flies like a fly, Modeled after a blowfly, it is powered by tiny electric actuators along its sides. The wings beat up to 275 times per second, even faster than real blowflies. To make such a fly he used micromachines and a rapid prototyping system that allowed him to design the minuscule parts on a commuter, automatically cut and cure them over night and assemble them by hand under a microscope. The fly wing were made of two-micron polyester sheets reinforced with carbon fiber. The robot flies well enough. Fearing is currently attempting to get it to hoover, bank and dive.

Websites and Resources on Insects: Insect.org insects.org ; Insect Images.org insectimages.org ; BBC Insects bbc.co.uk/nature/life/Insect ; Insect and Arachnid entomology.umn.edu/cues/4015/morpology ; Wikipedia article Wikipedia ; Virtual Insect home.comcast.net ; National Geographic on Bugs National Geographic ; Smithsonian bug info si.edu/Encyclopedia_SI/nmnh/buginfo ; Entomology for Beginners bijlmakers.com/entomology/begin ; BugGuide bugguide.net ;

Websites and Resources on Animals: ARKive arkive.org Animal Info animalinfo.org ; Animal Picture Archives (do a Search for the Animal Species You Want) animalpicturesarchive ; BBC Animals Finder bbc.co.uk/nature/animals ; Animal Diversity Web animaldiversity.ummz.umich.edu ; International Field Guides media.library.uiuc.edu ; animals.com animals.com/tags/animals-z ; Encyclopedia of Life eol.org ; World Wildlife Fund (WWF) worldwildlife.org ; National Geographic National Geographic ; Animal Planet animal.discovery.com ; Wikipedia article on Animals Wikipedia ; Animals.com animals.com ; Endangered Animals iucnredlist.org ; Endangered Species Resource List ucblibraries.colorado.edu ; Biodiversity Heritage Library biodiversitylibrary.org

Houseflies and Hooverflies

The housefly is regarded by some as the most aerodynamically sophisticated creature on the planet: superior to any bird. It can make six turns a second, fly straight up and down and backwards, land on a ceiling and a do a somersault in mid air — and do all this with a brain that is smaller than sesame seed.

Houseflies evolved millions of years ago and were among the first animals to take to the air. They only have a dozen or so muscles used for maneuvering. Their acrobatic skill is attributed to a wide range of senors, including its compound eyes which are excellent at detecting motions and sensitive hairs and antennae that can sense even slight wind motions and directions. Roughly two thirds of a housefly’s nervous system is devoted to processing sensory and visual information. It can digest huge amounts of data and make a decision based on it in milliseconds.

Many scientists claim that hoverflies are the best fliers. They can hover in the air, dart of to one place and direction and fly right back to the original spot. Studies with some flies show that they can execute sophisticated areal moves with equilibrium organs in their backs that serve as gyroscopes.

Maggots as a Cure

Doctors are increasingly taking a serious look at maggots (flesh-eating fly larvae) as a treatment for severely wound and ulcerated legs because the treatment has proven to be effective, easy and cheap. Maggots are very good at cleaning festering, gangrenous wounds. They are used on diabetics and other people who have a hard time getting wounds to heal by pressing them into dying flesh with wire-mesh bandages. Greenfly larvae are given patients who are assured that the maggots will not burrow into their skin. Maggots are especially effective fighting the super bug antibiotic-resistant staphylococcus aureus.

Maggots eat dead tissues and killing bacteria that could block the healing process. The use of maggots was common in the 19th century and early 20th century but fell out of favor after antibiotic were invented. The practice was revived out of concerns of patient using too many antibiotics.

Among the cultures that have that have used maggots have been Aboriginals in Australia, hill tribes in Burma and the ancient Mayans. Napoleon’s doctor commented on their effects. In World War I doctors discovered that soldiers that had been left untreated had healthy, pink flesh under their maggot-infested wounds. Their efforts to promotes maggots as a form of treatment was dismissed after antibiotics became widely embraced.

Dr. Thomas Stuttaford wrote in the Times of London, “The value of maggots in removing irretrievably wound-damaged tissue came into its own in World War I...In trench warfare, wounded soldiers often had to lie in no man’s land for hours, sometimes a day or two, until they could be brought back by patrols after dark...My father , who was a doctor for three years in the trenches, said he always reassured the casualties whose wounds were playing host to maggots that, disgusting as they looked, they would hasten the healing of the their wounds....Claims that maggots may have antiseptic action that destroys bacteria are quite possibly true but more important is that they remove the decaying flesh that makes a wonderful culture on which bacteria flourish.”

Researchers have found that maggot treatment for a severe, festering wounds can reduce the duration time of the treatment from weeks to days and cut the cost from $4,400 to $600. A study by maggot-supplier Zoobiotoc published in the Journal of Wound Care found that an ulcerated leg could be treated effectively with12 boxes of maggots, each containing 300 maggots. To treat the same wound with hydrogel, the common treatment for leg ulcers, cost $4,400.

Dragonflies

Dragonflies are the first known flying creatures to appear on earth. They emerged about 320 million years ago. Most were around the size of modern dragonflies but with an absence of predators some with a wingspan of 70 centimeters evolved. They were largest insects that ever existed. Except for their size modern dragonflies have changed little since then.

Dragonflies have two sets of wings and simple joints between them. They can only move their wings up and down and can not fold them back. Even so they are excellent fliers, maneuvering all over the place and reaching speed of 30kph. They get around during the day using mosaic eyes and sensory hairs in the front of their body. Their inability to see at night keeps them grounded after the sun goes down.

Dragonflies and damselflies belong to the Odonata order of insects which embraces more than 6,000 species. Damselflies are generally smaller than dragonflies. Their wings fold back over their backs when they are at rest while dragonflies keep their wings extended outward. All Dragonflies and damselflies are predators who rely on their excellent sense of sight provided by their large compound eyes when seeking out prey. Dragonflies on the hunt use their front legs like tiny baskets to collect prey, mostly smaller insects. Large dragonflies will feed on smaller dragonflies.

Dragonflies are totally carnivorous. They don’t munch on plants nor sip nectar. Their entire diet consists of live prey they catch themselves. Many species hunt while in flight using their speed and maneuverability to chase down prey. This hunting method is known to scientists as “hawking.” Another common technique, known as “sallying,” is for the dragonflies to wait patiently on a perch and then dart out suddenly to grab prey. A third technique, “gleaning,” involves hoovering or flying around a spot and picking prey off the ground or vegetation.

Dragonfly Development

Dragonflies begin as eggs deposited in water. They live in the water as predatory larvae called naiads after Greek water spirits. They have extendable jaws that snap shut with lightning speed to snare prey which then have their juices sucked out of them by the naiad’s sharp-tipped strawlike mouthpiece. The first stage larvae are so small they can feed only on water fleas but as they get bigger they can prey on small fish, tadpoles and even frogs.

Dragonflies often emerge from their larval skin at night. Their wings harden usually by morning but usually don’t fly until later because their bodies take several days to fully harden and develop their characteristic bright colors. After they emerge from the larval stage they often live for only a couple of months. While they are molting the are vulnerable to attacks from birds.

Dragonfly Sex

Dragonflies have an unusual way of reproducing. Males produce sperm in one organ and then transfer it another organ that is called a penis but is not really one. In mid air the male clasps the female who curves her body until it reaches the penis. The mating take about an hour. During the first 20 minutes the penis locks itself inside the female with barbs and hooks and squeezes out the sperm of previous males. Only after this is done is the sperm released. [Source: Jennifer Ackerman, National Geographic, April 2006]

Sex is often rough and occasionally fatal. Males have claspers at the end of their abdomens that they use to clasp a special plate on the female’s thorax behind her head. Males often clasp and have sex with the females during mid flight. Some species engages in heavy thrusting. The vise-like claspers of some species pierce the female’s heads.

Most females have sex with more than one partner. After sex the males of some species drag the female around to prevent her from being inseminated by other males. In other species, males kidnap and rape the females they find basking in the sun. Among other species, males attack copulating couples, bite them both and steal away the female. Others attack the female while she is laying eggs, drowning here in the process.

Fireflies

Fireflies, or lightning bugs, are not flies. They are a kind of beetle that belong to their own family: Lampyridae (“shining ones”). There are about 2,000 different species, with about 200 in the United States alone. Different species flash in different ways. The flashmaking organ at the end of their abdomen is called a lantern. The flashing signals originate in the brain.

Fireflies emit light a an efficiency rate of 41 percent, compared to 30 percent for the LED (light-emitting diodes) — the most efficient man-made lights. Fireflies generate about 1/40th of a candle of light. They generally flash when they want sex. Like other bioluminescent creatures they combine oxygen, luciferin, and adenosine triphosphate (ATP) to produce light. ATP is a compound all plants and animals use for energy. Most food eaten by humans is converted to ATP.

The signal to flash travels from the brain to the lantern using nerve cells that never touch the lantern and molecules of nitric oxide that travels through cell membranes to the lantern. Nitric oxide is found in human brain but is different from nitrous oxide ("laughing gas").

In the United States there are concerns that firefly populations have been hurt by lawn pesticides, concrete sprawl and the capture of the insects for their chemicals which are used in scientific research.

Humans who catch fireflies and put tem in a jar are advised to make sure there are air holes and a damp piece of paper in the jar. They should be set free the following morning. Some people have had success using a penlight to attract females. One man who has had success doing this told the Washington Post, “You can convince the firefly that there’s female there so he’ll get close, and he’ll do it again.”

Firefly Flashing

It mostly males that do the flashing. They fly around the air, occasionally flashing, trying to attract the attention of females who are usually sitting stationary on the ground or on a bush. If a female responds with a blink or two she is telling the male she is interested enough to let him come and check her out.

Sometimes males have difficulty locating the females. Sometimes the females don’t flash back. Research indicates that females of some species prefer males that can flash longer and faster. Sometimes the response light is a ruse from a deadly larger species trying to attract a meal. When the male flies down to investigate he is devoured by the imposters who sometimes need the chemicals to ward off things that might eat it.

Fireflies spend years underground as larvae. There emerge for only a week or two. Their only mission is reproduce before they die. More than half of the males fail to mate. In temperate climates a wet spring often foretells a summer with lots of lightning bugs. Wet soil is thought to be good for both the fireflies and the things they eat.

Each species has distinctive flashing and flying patterns. The Big Dipper firefly, one of the most common in the Washington D.C. area, give a long flash while flying in a “J” pattern. “Photinus macdermotto” flies straight and slow, flashing twice every six seconds. Some flash are like Morse-code dot-and-dash messages.

Wasps

Some species of wasps have extremely weird and cruel parasitic life cycles. A number lay their eggs in the eggs or larvae of other insect species and the larvae that hatch feed in various ways on the eggs and larvae of their hosts.

The “Copidosama floridanum”, native throughout the United States and studied by Mike Strand of the University of Georgia, arguably has the weirdest life cycle of all, beginning 1) when an adult female wasp lays one or two eggs inside a cabbage looper moth egg. 2) As the moth egg develops into five-to seven-centimeter-long caterpillar, the grape-like wasp eggs release about 3,000 genetically-identical maggot-like wasp larvae, most of which drink the caterpillar’s blood. 3) Up to a quarter of the larvae take on snakelike “soldier” forms that attack wasp larvae and eggs which have the same mother they do. 4) The bloodsucking larvae that are not killed by soldiers devour their hosts and pupae. 5) The wasps that develop from the surviving larvae and eggs eventually fly away, leaving the soldier larvae trapped inside the mummified caterpillar. [Source: Carl Zimmer, New York Times, August 14, 2007]

See Tarantulas

Hornets

Hornets are omnivorous insects. They feed on nectar but also hunt grasshoppers, crickets and other insects. Typically they sting their prey cut them apart with their powerful jaws, and the carry the cut up pieces back to their nest and feed them to growing larvae. The nests of temperate hornet species, which can reach the size of a beach ball, are constructed from spring through autumn and abandoned in the winter and a new nest is built. At that time of the year males emerge and fly off to different places and wait there for female queens to show up. After the queens come out they mate with males and then look for a nice warm, dry spot to spend the winter. In the spring new queens begin building a new nest from scratch.

Hornets have a smooth stinger that slides in and out of their targets. They uses it for hunting and are able to use it repeatedly. In contrast bees have a barbed stinger that pulls off when inserted and yanked. They sting only in defense and use their stinger only once.

Temperate hornets are often aggressive in late autumn when the new queens develop, workers become more protective, food become scarcer and large species of hornets attack the nests of smaller species. If attacked by a hornet get as far away as possible from the nest as soon a possible, the initial attackers placed a pheromone onto the skin of its target — whether it be a person or animal — that identifies it as an enemy and the target for other hornet attacks.

Hornet Life Cycle

Kevin Short wrote in the Daily Yomiuri: Hornets “construct large nests. A single queen starts the nest in early spring, and her offspring, the workers, continue to expand it well into autumn. By this time of year, the nests are reaching maximum size, and in some species may house several thousand workers. Workers, although all females, do not mate or lay eggs. Their job description includes building the nest, hunting for food for the larvae and defending the colony against intruders. Come winter all of them will die off. Genetically programmed to be totally unselfish, if threatened they will defend the nest with reckless abandon. [Source: Kevin Short, Daily Yomiuri, October 18, 2012]

As autumn wanes, a change comes over the nest. Until now all the larvae were destined to metamorphose into additional workers. Now, however, two special types of larvae are being raised. One type will metamorphose into males, and the other into a cadre of new queens. After metamorphosing, the males will leave their natal nest. They will fly around looking for another nest of the same species, then just sort of hang out idly on the outskirts. When the new queens emerge, the males will be waiting there to mate with them. Their one and only function in life is mating, and they die soon afterward. [Ibid]

After mating, the new queens will preserve the males' sperm in special pockets, then search for a warm cozy place to spend the winter. When they reawaken next spring, each queen will start building a nest of her own from scratch. All hornet nests, including some that are as big as a beach ball, have been constructed over the course of a single season. The founder queen and all the workers will die with the coming cold, and the old nest will be abandoned. [Ibid]

An autumn nest is the product of six months of hard work, the sole purpose of which is to raise a set of males and new queens to foster the next generation. As might be expected, the workers become especially sensitive and aggressive while the new queens and males are growing inside. Their attack threshold in mid to late autumn is thus considerably lower than in the warmer months. [Ibid]

Hornets and Bees

Kevin Short wrote in the Daily Yomiuri: Hornets are close relatives of bees, but are fundamentally different in terms of feeding ecology. Bees raise their larvae on nectar and pollen collected from flowers. Hornets, in contrast, do sip pollen and nectar for short-term energy boosts, but feed their larvae a steady meat diet. They hunt and kill caterpillars, grasshoppers and other insects, then use their powerful jaws to cut out bite-size pieces to carry back to the nest. [Source: Kevin Short, Daily Yomiuri, October 18, 2012]

Bees sting only to protect their nests. In many species, the poison stinger is tipped with a barb that catches in the flesh of the enemy. When the bee pulls away, her abdomen rips apart, leaving the barbed stinger inside the victim. These bees can sting only once. Hornets, however, use their stingers not only in defense of the nest, but in their daily hunting chores as well. Their stingers are thus not barbed, and can be used over and over again. [Ibid]

Local farmers are a bit ambivalent about the local hornets. On the one hand, they recognize that these predatory insects eliminate large number of caterpillars and other crop pests. On the other hand, farmers who keep honey bees to pollinate their strawberries and other fruits and vegetables fear the hornets. The larger species often attack honey bee hives to get at the larvae inside. A squadron of a few dozen hornets can wipe out an entire hive in no time. [Ibid]

Imported European honey bees have no defenses against a hornet raid. The workers rush out bravely, but are quickly cut to pieces by the hornets' powerful jaws. The ground around a raided hive will be littered with decapitated bees. Native Japanese honey bees, however, have evolved alongside the hornets, and have developed a technique for protecting themselves. Rather than trying to sting the intruders, they simply blanket them in huge numbers. This raises the hornets' body temperature and kills them.

Bees

Bees have barbed stingers that pull out when inserted in a target and yanked out. They sting only in defense and use their stingers only one. In contrast hornets have a smooth stinger that slides in and out. They use it for hunting as well as defense and are able to use it repeatedly.

A French mathematician concluded in 1934 that it defied science that bumble bees were able to fly. Bumble bees and other beers do have small wing to body sizes but are able to compensate for this by working harder than other insects and flapping their wings in unusual ways. Their unorthodox flapping methods lets them hoover, evade predators and get lift even when loaded up with nectar.

Most flying insects move their wings in long, sweeping strokes (140 to 165 degrees) at roughly 200 beats a second. But honeybees flap in short arcs (about 90 degrees) so they have to compensate with more speed (up to 240 times a second). To beat gravity bees beat their wings plus flip them. When they fly bees: 1) first flap forward creating a vortex above the bee and generating lift. 2) The wings then rotate and slow down in preparation for the backward stroke. 3) In the next step the wings finish rotating and start sweeping backwards, utilizing the previous stroke’s wake. And 4) Finally, the wings fling backwards, creating a new vortex in the process. The cycle then repeats.

Bees are widely used to pollinate agricultural plants. Beekeeping is encouraged in many places as a way for poor farmers to make supplementary income.

Bees and Honey

Bees gather nectar — the thin, sweet, watery, liquid found in flowers — and deposit it in the honey combs of their hives, where it goes through chemical reactions to become honey. A gallon of honey weighs 12 pounds. One pound of contains the nectar from two million flowers gathered on trips between the hive and flowers by bees.

Honey is composed mostly of sugars: levulose (40.5 percent), dextrose (34 percent), and sucrose (1.9 percent). It also contains minerals such as iron, copper, sodium, calcium and potassium. The taste of the honey is often determined by which flowers are fed on by the bees. In the United States most commercial honeybees gather nectar from five plants: clover, buckwheat, alfalfa, orange trees and cotton.

Honey was really the only source of sweetening before sugar became widely cultivated in the 16th century. Athletes in the ancient Olympics ate honey for energy. Bees were first domesticated around A.D. 500.

Bee Group Behavior

Even though groups of honeybees often differ in where to establish a new nest, the group usually chooses the best site. Bees reach a decision by gathering information, conducting independent evaluations and holding a kind of vote. Traders of some commodities such as soy bean futures use similar strategies. [Source: National Geographic, July 2007]

Thomas Seely, a biologist at Cornell University, has studied how bees make decisions about nesting sites by applying tags and dots to several thousand bees and watching how they act when they search for a site to make a new hive with the only possibilities being boxes of different sizes. In his experiments bee scouts check out the boxes and return to the nest and give information about the boxes and their location to other bees through an elaborate dance. As soon as the number of visible scouts outside the entrance of a box reaches 15, the tipping point, news begins to be relayed about the box with the 15 scouts and the swarm begins taking steps to move there.

Seely told National Geographic, “It’s a race. Which site was going to build up 15 bees first.” He said the has applied the rules he learned about bee decision-making — seeking a diversity of opinions, encouraging free competition among participants, and forming an effective means to narrow choices — at faculty meetings and the methods have produced good results.

Bee Colony Collapse Disorder

In the mid 2000s, beekeepers in the United States began experiencing huge loses due to a phenomena called Colony Collapse Disorder is which bees suddenly abandon their hives perhaps because of some mysterious disease. In many cases the hives are empty except for a queen and handful of bees and honey and pollen.

During the spring of 2007 a quarter of the 2.4 million honeybee bee colonies in the United States were lost. Similar reports have come from Brazil, Spain, Germany, Japan and Taiwan. Bees observed in hives that were in process of collapse had a number of diseases. The matter is being treated quite seriously. A third of the food supply is dependent on animal pollinators, with honeybees being one of the main players.

There are lots of theories as to what was happening — everything from a reaction to pesticides to the effects of cell phones — but no one has yet come up with a good explanation. Officials at the U.S. Department of Agriculture think it might be related to the stress bees used as commercial pollinators experiences as they are loaded on 18-wheel trucks and moved across the country to pollinate everything from almonds to watermelons.

Image Sources:

Text Sources: Mostly National Geographic articles. Also “Life on Earth” by David Attenborough (Princeton University Press), New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated January 2013


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