10 Fascinating Facts About Aphids

10 Fascinating Facts About Aphids

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  • B.A., Political Science, Rutgers University

As the joke goes, aphids suck. And while this is both literally and figuratively true, in some respects, any entomologist will tell you that aphids are interesting and sophisticated insects.

Aphids Poop Sugar

Aphids feed by piercing the phloem tissue of the host plant and sucking up the sap. Unfortunately, sap is mostly sugar, so an aphid must consume a lot of sap to meet its nutritional requirement for protein. Much of what the aphid consumes goes to waste. The excess sugar is eliminated in the form of a sugary droplet called honeydew. An aphid-infested plant quickly becomes coated in the sticky excretions.

Sugar-Loving Ants Tend to Some Aphids

Anyone who has battled sugar ants in their kitchen can tell you that ants have a sweet tooth. Ants are therefore very fond of bugs that can poop large quantities of sugar. Aphid-herding ants will care for their adopted aphids, carrying them from plant to plant and «milking» them for honeydew. In exchange for the sweet treats they get from the aphids in their care, they provide the aphids with protection from predators and parasites. Some ants even take the aphids home to their nest during the winter months, keeping them safe until spring.

Aphids Have a Lot of Enemies

I’m not just talking about gardeners, either. Aphids are slow, they’re plump, and they’re sweet to eat (presumably). A single plant can host hundreds or even thousands of aphids, offering predators a real smorgasbord of snacks. Aphid eaters include lady beetles, lacewings, minute pirate bugs, hoverfly larvae, big-eyed bugs, damsel bugs, and certain stinging wasps, among others. Entomologists even have a term for the many insects that feed on aphids – aphidophagous.

Aphids Have Tailpipes

Most aphids have a pair of tubular structures on their hind ends, which entomologists describe as looking like tiny tailpipes. These structures, called cornicles or sometimes siphunculi, seem to serve a defensive purpose. When threatened, an aphid releases a waxy fluid from the cornicles. The sticky substance gums up the mouth of the predator in pursuit and is thought to trap parasitoids before they can infect the aphid.

Aphids Sound an Alarm When They’re in Trouble

Like many insects, some aphids use alarm pheromones to broadcast a threat to other aphids in the area. The aphid under attack releases these chemical signals from its cornicles, sending nearby aphids running for cover. Unfortunately for the aphids, some lady beetles have learned the aphid language, too. The lady beetles follow the alarm pheromones to locate an easy meal.

Aphids Fight Back

Aphids may look defenseless, but they don’t go down without a fight. Aphids are expert kickboxers and will pummel their pursuers with their hind feet. Some aphids bear spines that make them challenging to chew on, and others are merely thick-skinned. Aphids are also known to go on the offensive, stabbing the eggs of predatory insects to kill their enemies in vitro. If all else fails, aphids stop, drop, and roll off their host plant to escape predation.

Some Aphids Employ Soldiers for Protection

Although not common, certain gall-making aphids produce special soldier nymphs to protect the group. These female guards never molt into adulthood, and their sole purpose is to protect and serve. Aphid soldiers are fiercely committed to their job and will sacrifice themselves if needed. Soldier aphids often have burly legs with which they can detain or squeeze intruders.

Aphids Lack Wings (Until They Need Them)

Aphids are generally apterous (wingless), and unable to fly. As you might imagine, this can put them at a considerable disadvantage if environmental conditions deteriorate, since they aren’t very mobile. When the host plant becomes a little too crowded with hungry aphids, or if it’s sucked dry and there’s a lack of sap, the aphids may need to disperse and find new host plants. That’s when wings come in handy. Aphids will periodically produce a generation of alates – winged adults capable of flight. Flying aphids don’t set any aviation records, but they can ride a wind gust with some skill to relocate.

Female Aphids Can Reproduce Without Mating

Because aphids have so many predators, their survival depends on their numbers. A quick and easy way to boost the population is to dispense with the nonsense of mating. Female aphids are parthenogenetic, or capable of virgin births, no males required. Like Russian nesting dolls, a female aphid may carry developing young, which are themselves already carrying developing young. This significantly shortens the development cycle and increases population numbers rapidly.

Aphids Give Birth to Live Young

You might expect a bug that seems so primitive to lay eggs like more other insects do, but aphids are pretty sophisticated when it comes to reproduction. There isn’t time to wait for eggs to develop and hatch. So aphids practice viviparity, giving birth to live young. The aphid’s eggs begin to develop as soon as ovulation occurs, without any fertilization.

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Aphids

Aphids are insects in the order Homoptera, also known as plant lice. Some 3, 800 aphid species have been identified worldwide with 1, 300 species found in North America, which includes some 80 species classified as pests of crops and ornamental plants. Aphids have a distinctive pear-shaped body, and most are soft and green in color. The wings are transparent and held in a tent-like position over the abdomen, which has a short tail, called a cauda. The legs are long and thin, as are the six-segmented antennae. Two tube-like structures, called cornicles, project from the fifth or sixth abdominal segment and excrete a defensive chemical when the aphid is threatened.

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Reproductive habits

Aphids have a complicated life cycle and reproduction habits that make them extremely adaptable to their host plants and environments. When aphid eggs

that have overwintered on their host plants hatch in the spring, they produce females without wings. These females are capable of reproducing asexually, a process called parthenogenesis. Several asexual generations may be produced during a growing season.

When it becomes necessary to move to another plant, winged females are produced. As winter approaches, both males and females are produced and their fertilized eggs again overwinter until the next spring. Sometimes winged females that produce asexually also migrate to new hosts. The lack of wings among generations of aphids that have no need to migrate is seen as an adaptive advantage, since it helps keep them from being blown away in windy weather.

Ants and aphids

Ants and aphids A symbiotic relationship exists between ants and aphids. They are often compared to cattle, with the ants acting as protectors and ranchers. Aphids secrete a sweet substance called honeydew, which contains surplus sugar from their diet. Ants protect aphid eggs during the winter, and carry newly hatched aphids to new host plants, where the aphids feed on the leaves and the ants get a supply of honeydew.

Because they reproduce rapidly and grow large colonies, an aphid infestation stunts growth, inhibits the crop production, and can even kill the host plant. Aphids can also carry other diseases, such as viruses, from one plant to another. Their saliva is also toxic to plant tissues. Among the biological controls of aphid infestations in agriculture and horticulture are lacewings, sometimes called “ aphid lions, ” lady beetles or ladybird beetles (ladybugs), and syrphid flies. Pesticides, including diazinon, disyston, malathion, nicotine sulfate, and others, are also used to control aphids. On a smaller scale, some gardeners control aphids by simply washing them off with a spray of soapy water.

KEY TERMS

Honeydew — A sweet substance excreted by aphids that ants utilize as food.

Parthenogenesis — Asexual reproduction without the fertilization of eggs.

Symbiosis — A biological relationship between two or more organisms that is mutually beneficial. The relationship is obligate, meaning that the partners cannot successfully live apart in nature.

Resources

BOOKS

Arnett, Ross H. American Insects. New York: CRC Publishing, 2000.

Hubbell, Sue. Broadsides from the Other Orders: A Book of Bugs. New York: Random House, 1993.

Imes, Rick. The Practical Entomologist. New York: Simon & Schuster, 1992.

McGavin, George C. Bugs of the World. London: Blandford Press, 1999.

Vita Richman
Neil Cumberlidge

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Aphids

Aphids

Aphids are insects in the order Homoptera, which are also known as plant lice. Some 3,800 species of aphids have been identified worldwide with 1,300 species occurring in North America , which includes some 80 species that are pests of crops and ornamental plants. Aphids have a distinctive pear-shaped body, and most are soft and green in color . The wings are transparent and are held in a tent-like position over the abdomen, which has a short tail, called a cauda. The legs are long and thin, and the antennae are thin and have six segments. Two tube-like structures, called cornicles, project from the fifth or sixth abdominal segments of aphids. The cornicles excrete a defensive chemical when the aphid is threatened.

Reproductive habits

Aphids have a complicated life cycle and reproduction habits that make them extremely adaptable to their host plants and environments. When aphid eggs that have overwintered on their host plants hatch in the spring, they produce females without wings. These females and are capable of reproducing asexually, a process called parthenogenesis . Several asexual generations of aphids may be produced during a growing season.

When it becomes necessary to move to another plant, females with wings are produced and move to another host plant. As winter approaches, both males and females are produced and their fertilized eggs again overwinter until the next spring. Sometimes winged females that produce asexually also migrate to new hosts. The lack of wings among generations of aphids that have no need to migrate is seen as an adaptive advantage, since it helps keep them from being blown away in windy weather .

Ants and aphids

An intimate, symbiotic relationship exists between ants and aphids. They are often compared to cattle, with the ants acting as protectors and ranchers. What aphids have that ants want is something called honeydew, a sweet substance that is excreted by aphids through their anus and contains surplus sugar from the aphid’s diet. Ants protect aphid eggs during the winter, and carry the newly hatched aphids to new host plants, where the aphids feed on the leaves and the ants get a supply of honeydew.

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Because of their ability to reproduce rapidly and grow large colonies, their feeding on plants causes yellowing, stunting, mottling, browning, and curling of leaves, as well as inhibiting the ability of the host plant to produce crops. Infestations by aphids can cause plants to die, and the insects can carry other diseases, such as plant viruses, from one plant to another. Their saliva is also toxic to plant tissues. Among the biological controls of aphid infestations in agriculture and horticulture are lacewings , sometimes called «aphid lions,» lady beetles or ladybird beetles (ladybugs), and syrphid flies . Pesticides , including diazinon, disyston, malathion, nicotine sulfate, and others, are also used to control aphids. On a smaller scale, some gardeners control aphids by simply washing them off with a spray of soapy water .

Resources

books

Arnett, Ross H. American Insects. New York: CRC Publishing, 2000.

Hubbell, Sue. Broadsides from the Other Orders: A Book ofBugs. New York: Random House, 1993.

Imes, Rick. The Practical Entomologist. New York: Simon & Schuster, 1992.

McGavin, George C. Bugs of the World. Blandford Press, 1999.

Vita Richman Neil Cumberlidge

KEY TERMS

—A hard, shell-like structure that serves both to protect the vital organs of animals without an internal skeleton and to support their muscle systems.

—A sweet substance excreted by aphids that ants need.

—Asexual reproduction without the fertilization of eggs.

—Openings that lead to a system of tubes that supply air to insects.

—A biological relationship between two or more organisms that is mutually beneficial. The relationship is obligate, meaning that the partners cannot successfully live apart in nature.

Cite this article
Pick a style below, and copy the text for your bibliography.

www.encyclopedia.com

6 surprising facts about ladybugs

People love ladybugs. And what’s not to love? They’re cute as a button with their teeny hard, red shells with black spots. It’s even considered good luck if one lands on your hand or you see one in your home. Plus, they’re completely harmless to humans. Farmers love ladybugs because they enjoy feasting on plant-eating insects like aphids, according to National Geographic.

But ladybugs are disappearing across the United States, and scientists don’t know why. One theory is that non-native species, such as the seven-spotted ladybug from Europe (Coccinella septempunctata) and the Asian ladybug (Harmonia axyridis), have proliferated so successfully here that native ladybugs have been pushed out of sight. Another theory says those non-native species are due for a decline themselves, so the disappearance may just be part of a natural cycle.

www.mnn.com

10 Fascinating Facts About Fireflies

Light is used to draw prey and sex partners and to warn off predators

tomosang / Getty Images

  • B.A., Political Science, Rutgers University

Fireflies, or lightning bugs, are from the family Coleoptera: Lampyridae and they might be our most beloved insect, inspiring poets and scientists alike. Fireflies are neither flies nor bugs; they are beetles, and there are 2,000 species on our planet.

Here are other interesting facts about fireflies:

Flight

Like all other beetles, lightning bugs have hardened forewings called elytra, which meet in a straight line down the back when at rest. In-flight, fireflies hold the elytra out for balance, relying on their membranous hindwings for movement. These traits place fireflies squarely in the order Coleoptera.

Efficient Light Producers

An incandescent light bulb gives off 90% of its energy as heat and only 10% as light, which you’d know if you’ve touched one that’s been on for a while. If fireflies produced that much heat when they lit up, they would incinerate themselves. Fireflies produce light through an efficient chemical reaction called chemiluminescence that allows them to glow without wasting heat energy. For fireflies, 100% of the energy goes into making light; accomplishing that flashing increases the firefly metabolic rates an astonishingly low 37% above resting values.

Fireflies are bioluminescent, meaning they are living creatures that produce light, a trait shared with a handful of other terrestrial insects, including click beetles and railroad worms. The light is used to attract prey and members of the opposite sex and to warn off predators. Lightning bugs taste bad to birds and other potential predators, so the warning signal is memorable for those that have sampled before.

‘Talk’ Using Light Signals

Fireflies don’t put on those spectacular summer displays just to entertain us. You’re eavesdropping on the firefly singles bar. Male fireflies cruising for mates flash a species-specific pattern to announce their availability to receptive females. An interested female will reply, helping the male locate her where she’s perched, often on low vegetation.

Bioluminescent for Life

We don’t often see fireflies before they reach adulthood, so you might not know that fireflies glow in all life stages. Bioluminescence begins with the egg and is present throughout the entire life cycle. All firefly eggs, larvae, and pupae known to science can produce light. Some firefly eggs emit a faint glow when disturbed.

The flashing part of fireflies is called a lantern, and the firefly controls the flashing with neural stimulation and nitric oxide. The males often synchronize their flashes with one another during courtship, a capacity called entraining (responding to an external rhythm) once thought only possible in humans but now recognized in several animals. Colors of firefly lights range widely among different species, from yellow-green to orange to turquoise to a bright poppy red.

Lives Spent Mostly as Larva

The firefly begins life as a bioluminescent, spherical egg. At the end of the summer, adult females lay about 100 eggs in soil or near the soil surface. The worm-like larva hatches out in three to four weeks and throughout the fall hunts prey using a hypodermic-like injection strategy similar to that of bees.

Larvae spend the winter below ground in several types of earthen chambers. Some species spend more than two winters before pupating in late spring, emerging as adults after 10 days to several weeks. Adult fireflies live only another two months, spending the summer mating and performing for us before laying eggs and dying.

Not All Adults Flash

Fireflies are known for their blinking light signals, but not all fireflies flash. Some adult fireflies, mostly those in western North America, don’t use light signals to communicate. Many people believe that fireflies don’t exist west of the Rockies since flashing populations are rarely seen there, but they do.

Larvae Feed on Snails

Firefly larvae are carnivorous predators, and their favorite food is escargot. Most firefly species inhabit moist, terrestrial environments, where they feed on snails or worms in the soil. A few Asian species use gills to breathe underwater, where they eat aquatic snails and other mollusks. Some species are arboreal, and their larvae hunt tree snails.

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Some Are Cannibals

What adult fireflies eat is largely unknown. Most don’t seem to feed at all, while others are believed to eat mites or pollen. We do know that Photuris fireflies eat other fireflies. Photuris females enjoy munching on males of other genera.

These Photuris femmes fatales use a trick called aggressive mimicry to find meals. When a male firefly of another genus flashes its light signal, the female Photuris firefly replies with the male’s flash pattern, suggesting she is a receptive mate of his species. She continues luring him in until he’s within her reach. Then her meal begins.

Adult female Photuris fireflies are also kleptoparasitic and can be seen feeding on silk-wrapped Photinus species fireflies (occasionally even one of their own kind) hanging in a spider’s web. Epic battles can occur between the spider and the firefly. Sometimes the firefly can hold off the spider long enough to consume the silk-wrapped prey, sometimes the spider cuts the web and her losses, and sometimes the spider catches the firefly and the prey and has them both wrapped in silk.

Enzyme Used in Medicine

Scientists have developed remarkable uses for firefly luciferase, the enzyme that produces bioluminescence in fireflies. It has been used as a marker to detect blood clots, to tag tuberculosis virus cells, and to monitor hydrogen peroxide levels in living organisms. Hydrogen peroxide is believed to play a role in the progression of some diseases, including cancer and diabetes. Scientists now can use a synthetic form of luciferase for most research, so the commercial harvest of fireflies has decreased.

Firefly populations are shrinking, and the search for luciferase is just one of the reasons. Development and climate change have reduced firefly habitats, and light pollution depresses the ability for fireflies to find mates and reproduce.

Flash Signals Synchronized

Imagine thousands of fireflies lighting up at the same time, over and over, from dusk to dark. Simultaneous bioluminescence, as it is called by scientists, occurs in just two places in the world: Southeast Asia and Great Smoky Mountains National Park. North America’s lone synchronous species, Photinus carolinus, puts on its light show annually in late spring.

The most spectacular show is said to be the mass synchronous display of several Pteroptyx species in Southeast Asia. Masses of males congregate in groups, called leks, and in unison emit rhythmic courtship flashes. One hot spot for ecotourism is the Selangor River in Malaysia. Lek courting happens occasionally in American fireflies, but not for long periods.

In the American Southeast, male members of the blue ghost firefly (Phausis reticulate) glow steadily as they fly slowly over the forest floor searching for females, from about 40 minutes after sunset until midnight. Both sexes emit a long-lasting, nearly continuous glow in the forested regions of Appalachia. Annual tours to see the blue ghosts can be taken at state forests in South and North Carolina between April and July.

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Aphids: Reproduction & Life Cycle

Bryan is a freelance writer who specializes in literature. He has worked as an English instructor, editor and writer for the past 10 years.

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Aphids at a Glance

If you have ever looked under the leaf of a flower or plant and found a cluster of tiny insects, you’ve most likely encountered aphids. Aphids are small sap-sucking bugs that feed on plants. They reproduce quickly, giving the scientific world plenty of opportunities to study them, and in turn providing us a lot of information on these creatures. Let’s investigate.

Reproduction

The sex life (or non-sex life) of the aphid is one of their most unusual features. Some aphids reproduce sexually, some reproduce asexually and some use both methods of reproduction depending on their environment. With asexual reproduction, females can either give birth to live clones or lay eggs, all without a male aphid.

For the aphids that do involve a male, it gets a little more complicated, but also more interesting. After laying eggs or creating clones, the new females are able to produce copies of themselves as well. When the weather heats up, some of the eggs hatch into males. When the males are sexually mature, they can mate with the female aphid, who then produces eggs that will survive over the winter and hatch into more aphids.

Life Cycle

Since some aphids use asexual reproduction and others use sexual, while still others use both, there are a few different paths their life cycle may take. The cycle is also affected by environmental factors. The average lifespan of an aphid is one month.

Holocyclic Life Cycle

In a holocyclic life cycle, the aphid starts as an egg that is usually planted before winter. From there it hatches into a fundatrix, which is a wingless female aphid. Next, the fundatrix will create daughter clones. These females will then go on to create both males and females. These males and females mate and create an egg that can survive the winter.

Anholocyclic

In an anholocyclic life cycle, female aphids simply create live birth clones of themselves without the help of males. So the life cycle usually looks like this: a female aphid which sometimes has wings and sometimes does not, creates a clone called an aptera. This aptera is unwinged and can survive the winter, then goes on to continue the cycle by creating more clones.

Host Changing

Some aphids change the host plant on which they make their home, causing their life cycle to differ slightly from others. They start out as eggs which hatch into fundatrices. These fundatrices create viviparous females, which means that they create the next generation inside their bodies, which are then born fully formed but smaller than the parent. This generation is where the magic happens. These females create the sexupara, which fly back to the original host and deposit both male and female aphids. These aphids mate to create the overwintering eggs, starting the entire cycle again.

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