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Beneficial Insect Spotlight: Paper Wasp

Right outside our back door, we have a small herb garden.  Last fall, we planted three parsley plants at the back of the herb garden.  This spring, they grew considerably at first and then immediately started flowering and haven’t stopped now for several weeks.   Because the herb garden is so close to our back patio door, we often stand at the door and watch a variety of insects that stop to enjoy the parsley flower nectar.   This plant really attracts an assortment of flies (houseflies, tachinid flies, hoverflies), wasps (paper wasps and thread-waists), and bees (honeybees, sweat bees, mason bees and solitary bees)!  Many of these insects prefer the shallow nectaries of flower umbrels as opposed to other species of flowers with deep nectaries which require elongated mouthparts.

umbrels of parsley flowers

My wife, who is understandably a little alarmed by the number of bees and wasps by our back door (she’s allergic to their stings), asked me why we want so many wasps in the garden.  She understands that parsley is the host plant for Eastern Black Swallowtail caterpillars and can appreciate the beauty that adult butterflies bring to the garden, but wasps are an entirely different story in her book.  I explained to her that wasps are beneficial insects to gardeners.  She then asked me, “In what way are they beneficial?”  To her, they seem like a pest to avoid and not one to invite so freely into the garden.

The fact of the matter is that wasps are beneficial insects in the garden for two main reasons.  The first is that they are pollinators.  I find wasps on a number of flowering plants in the garden, including squash, cucumber, zucchini and melons.  This family of plants, called cucurbits, have unisexual flowers, meaning that each flower either contains anthers or ovaries (i.e. is male or female), but not both.  They cannot self-pollinate.  Pollinators such as butterflies, bees and wasps are drawn to the flowers of these plants by color and are enticed to stay by the nectar that the flowers offer.   As they lap up the sweet goodness, the flower’s pollen sticks to the legs and bodies of the pollinator, which then flies to another flower and deposits some of this pollen there.  With regards to cucurbits, the male and female flowers need pollen from one another in order to produce fruit.  Pollinators are the key to making this happen as they move from male flower to female flower, depositing pollen.

Wasps are beneficial in another way.  They are parasitic.  They feed on a number of garden pests, including flies, beetle larvae and even caterpillars.  To me, this is where wasps fall into a sort of gray area when you are butterfly gardening.  Naturally, a butterfly gardener wants to raise butterfly larvae to adulthood, but other creatures in the garden see butterfly larvae as a good meal.  So, there’s a catch-22 here.  A butterfly gardener grows plants that attract beneficial insects, and some of those beneficial insects end up killing one another.  Wasps do their part, however, since out-of-control caterpillar populations can decimate plants and crops.  Still, I cringe at the thought of my little caterpillars preyed upon by wasps and even birds.  It is nature, however, and everything exists in balance, so I have to let the natural process play out.  All things considered, wasps are beneficial to my garden – I just wish they preyed exclusively on beetle larvae!

The Paper Wasp

If you’ve ever seen a wasp nest in the shape of an umbrella hanging from a thin thread under the eaves of a house, then you’ve seen how paper wasps live and how they got their name.  Paper wasps gather fibers from plants, chewing and mixing them with saliva to form a substance similar to paper, which is then formed into nests with many adjoining hexagonal cells.

Nests are started by a single queen in the spring, which can grow to hold up to two hundred cells.  The queen overwinters in brush or wood piles and emerges in the spring to expand her kingdom.  After picking a suitable spot for a nest, she works tirelessly, gathering and chewing plant fibers and forming the first several cells.   In these cells, the queen lays her eggs, which hatch into worker (non-queen females) and male larvae.  As the brood grows, the queen continues to do most of the egg-laying and studies show that her behavior actually suppresses the ovarian functions in subsequent female wasps so that she remains the dominant female.  Workers care for the queen’s larvae and continue to build the nest, while also visiting the field to harvest nectar, plant fibers and insects for larval food.

Adult wasps do not eat insects, they subsist entirely upon nectar.  Workers collect caterpillars and carry them back to their nests, first stinging them to paralyze them.  Then they stuff the paralyzed caterpillar into one of the prepared cells, and the queen deposits a single egg on the caterpillar’s body.  The egg hatches and a tiny wasp larva emerges and finds all the food it could possibly need until it pupates and emerges as an adult, winged wasp.

Males are needed only for fertilization of the queen.  The queen has a specialized organ called the spermatheca, which captures and holds the male wasp’s sperm for later fertilization of eggs.  Males typically live short lives.  Late in the season, they mate with female offspring of the queen, which then leave the colony to overwinter and emerge in spring to start their own colony.  All other members of the colony, including the original queen, perish during the winter.  The newly mated female holds the sperm in her spermatheca until the following spring when she begins laying eggs on harvested caterpillars!

As far as hierarchy in the colony goes, the founding queen is generally the dominant queen, and rules over her workers to ensure their cooperation and subservience.  The most aggressive females will take up the role of queen should the founding queen die, and on rare occasions, aggressive females can root out the founding queen in a process called usurpation.  The aggressive female then takes over as queen, while the founding queen takes on the role of worker.  Despite this aggressiveness, paper wasps are not aggressive except in defense of their nests.  As I tell my wife, they won’t even bother you should you sit right next to the parsley flowers to watch them.  They are more interested in feeding than they are in you!

The photos below are of a red paper wasp (Polistes carolina) on parsley flowers.  This wasp is common from as far west as the Texas panhandle to the east coast up through New York.  They are quite large at an inch in length.

(Click on any photo to view larger)


Beneficial Insect Files: Cicada Killer Wasp

During the hot summer months, usually towards the end of July and into the early part of August, we begin to see many large wasps in Central Texas. These wasps are pale yellow and black and resemble yellow jackets, only these are much bigger and scarier looking. In fact, they are the largest wasp species in Central Texas (growing over an inch long). Meet the Cicada Killer Wasp.

Unlike many of its cousins, the cicada killer is mostly non-aggressive and rarely stings.  Males may fly at you when you approach their burrows or nectar sources, but luckily, they are incapable of stinging.   Female cicada killers are reported to sting only if provoked, (i.e. handled or stepped on).  Instead of using their stingers to defend their nest and attack aggressors like most wasps, female cicada killers use their stingers only to do the function they are named for: killing cidadas.  Their sting, however, does not actually kill the cicada; it permanently paralyzes them (1).

Cicada killers go after those noisy, chattering (some call it singing, but I don’t!) adult cidadas that seem to swell in numbers towards the middle of the summer.  You can find their alien-looking shells (actually a molted exoskeleton) on the sides of trees in early to mid summer.   Once they molt, then they start making noise by vibrating their tymbal muscles, which produces loud clicks as two tymbal membranes pop in and pop out.  This sound, albeit a beautiful love song between courting cicadas, leads the cicada killer wasp right to them.  Once stung by the  cicada killer wasp, the cicada takes a permanent nap, while the female works on getting it back to its nest.

The cicada killer lives in burrows dug into soft dirt or sandy areas at ground level. In this burrow, a single wasp makes up to sixteen short tunnels or cells (2), just large enough to hold an adult cicada, all attached to the main passageway leading in and out of the burrow. The female wasp drags and carries her paralyzed victim any way she can all the way from the tops of the trees down to the ground and into the burrow. This is a strenuous activity as the adult cicada can be just as large as the wasp herself. Once in the burrow, the wasp tugs the cicada into one of the prepared cells, then deposits a single egg on to it. After this, the wasp seals the tunnel shut.

When the egg hatches and the wasp larvae emerges, it finds a quick and easy meal to hold it over until it is ready to emerge from the burrow as an adult. The lives of cicada killers are short as the adults do not overwinter. They live their life in a single season, capture cicadas and lay their young before expiring. The larvae emerge and overwinter in the prepared cicada tomb, feasting entirely on the cicada until they reach maturity and emerge the following spring.

Adult cicada killer wasps feed exclusively on flower nectar. As such, they are beneficial pollinators to a small degree, but are furthermore helpful in that they kill excessive cicada populations (3).

Did you know?

Cicada wasps are solitary, predatory wasps, though there may be several wasps living in close proximity to each other.

The female does all the work, from digging the burrow, to stinging and dragging the cicada back to the burrow, and from laying the eggs to sealing the cicada in. The sole purpose of the male is for mating.

Beneficial Insect Files: Lady Beetle

Beneficial Insect Spotlight: Lady Beetle

I have been seeing more lady beetles in the garden lately, both on the wildflower patch and on the sunflowers. Since I was able to snap a few good pictures, I thought that I should add the lady beetle to our Beneficial Insect Files. They are, after all, one of the most beneficial bugs for gardeners and the one we hear the most about. In fact, lady beetle harvesting has become a booming business in recent years, with hundreds of thousands of beetles being purchased and shipped throughout the U.S. every year for commercial and private growers.

Lady beetles are more commonly known as ladybugs in the United States and Ladybirds in other parts of the world. They are not true bugs, but beetles, so the most common names are actually misnomers (Beetles worldwide get offended at being called bugs, and it is quite obvious that lady beetles are not birds!). Other nicknames include: lady fly, ladyclock and lady cow.

Whatever they may be called popularly, they are formally known as coccinellids (pronounced cox-ih-NEL-ids), a member of the beetle family. Coccinellids are found natively on almost every continent and there are an estimated 5,000 species with nearly 500 individual species in North America alone.

Life Cycle

The life cycle of the lady beetle spans from three to six weeks dependent upon certain environmental factors such as humidity and temperature. With the arrival of spring, hibernating adult female beetles emerge and,after a good feast, begin laying up to three hundred light-yellow eggs on the underside of leaves in small clusters of up to fifty eggs. In under a week, small larvae emerge and they begin feeding their voracious appetite. Larvae can consume several hundred adult aphids during this stage, which generally lasts two to three weeks. All of this eating finally triggers a pupa stage that lasts a week to ten days, after which time the adult beetle emerges. Lady beetles emerge yellow to orange with no spots. It takes several hours for the spots to form and up to a few days for the outer wings (called elytra) to turn their familiar red color.

In some areas, there may be up to six generations per year(1).

Defenses

Lady beetles are equipped with several defense mechanisms, the first of which is their bright red coloration, a universal warning to predators. When threatened, lady beetles also secrete a foul-smelling and bad-tasting chemical, which is called “reflex bleeding”. If this fails to divert the predator, lady beetles can also play dead like an opossum! Finally, they do have mandibles. While there are reports of humans being bitten by a lady bug, there is no venom, poison or allergic saliva to cause any harm. It may pinch a little, but more harm is caused by the shock of being bitten by such a cute insect!

Lady Beetle Collection for Commercial Sale

The majority of lady beetles collected for sale are obtained in the California mountains where they naturally gather in the millions in colonies. While lady beetles are beneficial insects to have in the garden, certain studies have shown that non-native beetles that are introduced into the garden are far less effective than native species in controlling and eliminating pests. According to these studies, “shipped-in beetles” tend to fly away, have no appetite for food, or eat far fewer pests than native species also studied – depending upon what time of year they are collected. Those collected in winter or early spring for spring release, for example, were found to be far less likely to stay put in one area. If you are a gardener buying in lady beetles to control aphids in your garden, however, you want them to stay in your garden not fly away! As such, the conclusion of the study was that “It would be better to rely upon local beetles to distribute themselves and multiply in accordance with nature’s balance” (2).

Attracting Lady Beetles To Your Garden

Given that certain studies show the ineffectiveness of releasing non-native lady beetles into the garden for pest control, it makes sense to do what one can to attract native species instead.

Lady beetles must have a food source. Their favorite is aphids, but some species are also known to eat a variety of pests including hornworms, cabbage worms and scale insects. Lady beetles also eat pollen for protein and are drawn to certain types of plants. If you want to attract lady beetles, the most effective plants are those of the mustard family, as well as certain grains and legume, cilantro, clover, fennel, dill, coreopsis, cosmos, marigolds, dandelions and yarrow. Try planting a variety of these to bring these beneficial insects to your garden (3).

Fact: An adult lady beetle must consume around 300 aphids before it starts laying eggs. A lady beetle must eat from three to ten aphids for each egg it will lay. In its lifetime, a lady beetle will consume up to 5,000 aphids.

Myth: A common myth is that the number of spots on its back indicates its age

Playing dead ...

Beneficial Insect Files: European Honey Bee

Beneficial Insect Spotlight: European Honey Bee


The European Honey Bee, also called the Western Honey Bee, is a species of honey bee that originated in Asia and Europe and was subsequently introduced to the Americas by European colonists.  The Latin name, Apis mellifera, meaning “honey-bearing bee”, is actually a misnomer as honey bees do not bear honey, but pollen.  Collected pollen and nectar is used to make honey back at the nest.  Honey bees are highly adaptable to different climates and have benefited as a species from their domestication by man.*  Since its introduction to North America in the mid-1800’s, the European Honey Bee has become the most important pollinator of cultivated crops in the United States.  Additionally, the honey bee is now naturalized on six of the seven continents (excluding Antarctica).

The honey bee is one of the most studied insects on the planet and one of three insects to have its entire genome mapped (also fruit fly and mosquito).  They are a highly social insect, surviving not in isolation, but as a member of a structured and complex community or colony, which live together in a nest or domesticated hive.   Although there are several different types of honey bee, only the European species has been domesticated for use by man for agriculture in the United States.  The other species include: the dwarf honey bee, the Indian honey bee, the giant honey bee, the mountain giant honey bee and the African/European hybrid honey bee, more notoriously known as “the Killer bee”.   There are even different races of the European species, including Italian, Carniolan and Caucasian, all of which are used in modern beekeeping.

The honey bee colony is comprised of three very distinct classes of bees: the queen, the drones, and the workers.  Each has a specific function to the community, its own biological structure, and even specialized instincts.   The queen is the only female in the colony that is capable of sexual reproduction; therefore, she is the mother of the other two classes as well as to any future queens.   A queen bee is able to lay over 1,500 eggs per day, an amount equal to her own body weight.  She is structurally different than the other bees in that she possesses a larger abdomen, her mandibles have sharp teeth, and her stinger is curved and smooth, allowing her to use it multiple times for defense.  She lives one to three years before the need to replace her arises, while other bees in the community live as short as six weeks (highly-labored worker bees during warm months).

Drone bees are the males of the community.   They lack stingers and are completely defenseless.  They are also entirely unable to feed themselves without help from worker bees.  Anatomically, drones are different from worker bees in that they do not have pollen baskets or wax glands; therefore, they cannot collect pollen, nectar, or produce royal jelly.  Their sole function is to mate with new queens.  Once doing so, drones die immediately.  The release of sperm by the drones requires a final, lethal convulsion.  The new queen then stores the sperm in an organ known as the spermatheca, located in her abdomen.  Amazingly, the sperm is viable as long as the queen lives.  As if dying in the act of reproduction isn’t enough, all drones that have not fulfilled that purpose when fall arrives are exiled from the nest by workers and soon perish because they lack the ability to eat autonomously.

Workers make up the majority of the colony of bees, with large colonies comprised by as many as 80,000 of them at their peak.  These bees aren’t called workers for nothing.  They alone are responsible for building and maintaining the nest, caring for young, raising new queens, producing and storing honey, producing royal jelly (the exclusive food of queen larvae), as well as gathering nectar, water and pollen from the environment.  Wax glands secrete a waxy substance, which is then used to build hexagonal cells, arranged together in what is called a comb.  Mixing collected nectar with their own saliva, workers produce honey as food.  Royal jelly, a highly nutritious food source for larvae, is excreted from glands on the worker bees’ heads.  Each cell they build is used to store these foods or to act as incubators for developing bees.

Workers are also responsible for maintaining ventilation and temperature of the hive. They have the ability to rapidly vibrate their flight muscles, which generates body heat.  Using their wings, they are able to fan this warm air to incubate the colony in cold months, or they simply use their wings to cool the colony during the summer.  Workers use this same process to kill weak, old or dying queens.  Surrounding the queen, they generate enough body heat that the queen is eventually killed.

In addition to all of these tasks, workers also have the task of defending the colony.  Each is equipped with a barbed stinger, which is designed to remain intact in the victim after the sting is delivered.  As workers sting, their stinger is literally ripped out of their bodies and they soon perish from the wound.  Upon doing so, they release a pheromone which attracts other bees in the area and rallies them for attack.

Larvae emerge a couple of days after the queen lays eggs.  The workers keep the larvae in individual cells where they are fed royal jelly for at least the first couple of days before their diet is switched to nectar and honey.  When a new queen is desired, worker bees construct a different sort of cell and feed the developing larvae an exclusive diet of royal jelly, which contains a variety of proteins, amino acids and carbohydrates.  This substance initiates a biological change in the developing larvae, and the larvae begins to grow into a queen instead of a worker.   Although it’s busy work maintaining a queen, the workers are busy raising their own kind most of the time.  Developing larvae (and there are several hundred in a colony) need to be fed many times a day!

After larvae mature into adult worker bees, they are, at first, confined to work in the hive.  For the first few weeks, their time is spent building and cleaning cells, feeding drones, developing larvae and the queen, as well as maintaining the colony temperature.  After this period of time, they are allowed to venture out into the field to secure provisions and provide for the common defense.

The most important benefits of the presence of honey bees is that of pollination of cultivated crops as well as reproduction of many flowering plants.  Many varieties of cultivated plants rely almost exclusively on the work done by bees to produce the fruits and veggies we consume.  Without bees, many plants would be unable to reproduce.  Pollination is itself a byproduct of a bee’s nectar and pollen collecting, but it is, nevertheless, an important symbiotic relationship upon which a lot depends.

Bees also produce beeswax, which man has found many great uses for (Burt’s Bees comes to mind!).  They also produce honey, an internationally-prized sweetener that never spoils.  Vials discovered in tombs in Egypt this past century contained preserved honey that was still unspoiled (albeit crystallized).  Local honey is also gaining a reputation for helping reduce allergies to local flowers and vegetation.  By consuming honey, the body slowly familiarizes itself to the proteins found in pollen from a number of local sources and ceases producing the allergic, auto-immune response experienced by allergy sufferers.

The importance of honey bees has been gaining popular attention in the past several years, especially since the mysterious disappearances of huge populations of bees worldwide since 1972.  Colony Collapse Disorder (CCD) is a term coined in 2006 to describe this phenomena.  That year, some countries reported up to 50% disappearance of bee populations.  Some blame modern agriculture’s use of synthetic chemicals, while others speculate that genetically modified foods, climate change or even cell phone waves might be partly to blame.     Nevertheless, any threat to the worldwide population of honey bee is also a threat to us because we rely upon bees in the cultivation of  our crops.

* * * * * * * * * * * * * * * * * * * * * *

Facts:

Did you know that almond pollination in California each year marks the largest use of pollinating bees anywhere in the world?  One-third of the total number of domesticated pollinating bees in the U.S. is put to work for this event!

Did you know that one-third of all cultivated crops in the United States rely upon the work of pollinators like honey bees?

** This entry is one of many highlighting the importance of beneficial insects in our environment.  Please see the B.I.F. page.

Beneficial Insect Files: Checkered White Butterfly

Beneficial Insect Spotlight:  Checkered White butterfly

The Checkered White butterfly is also known by its Latin name, Pontia protodice, and is quite abundant across the United States.  It is often confused with its close relative, the Western White (1) butterfly, which is found west of the Rockies (2).  Checkered Whites are often found in dry, open fields, along roads, on farmland, and even in residential areas where they seem less affected by city sprawl than other species.

The Checkered Whites love all members of the mustard family (including peppergrass and watercress), and choose these as their host plants, in addition to broccoli, collard and cabbage.  Adult butterflies lay their eggs one at a time on the leaves of these plants, where the growing caterpillars live out their lives, happily munching away on the buds, flowers and leaves.  The eggs are barrel-shaped and are yellow when laid, but then turn orange (3).  Caterpillars are soft green to gray-green in coloration with faint yellow stripes.  They can be found on their host plants and are more commonly known as cabbageworms.   As such, they are sometimes considered to be a minor pest on cultivated crops such as broccoli.   Adult butterflies like to sample a wide range of nectars, but seem to prefer Purple Coneflower (Echinacea) and purpletop Verbena.

You can identify Checkered Whites by their distinct markings.  They are often almost completely white butterflies.  Males are less colorful with fewer patterns, but have at least two black spots on their forewings.  Females display the more identifiable checkered pattern in black, gray and white on the edges of their forewings.  Identification is a little more difficult west of the Rockies where Checkered Whites can be found along with the Western Whites.   Experts say that Western Whites have a slightly darker checkered pattern than their cousin, but the easiest way to tell them apart is by comparing males of the two species.  The row of dark spots on the male Western White is darker than the spots of the male Checkered White, and the hind wing is devoid of coloration or pattern.  Checkered Whites can produce three generations between March and November in cooler climates and four to five generations in warmer climates like ours.

The Checkered White butterfly is a beneficial insect because it is a widespread pollinator and an important food source for many vertebrates.  When you consider that one-third of the world’s cultivated crops depend upon the work of pollinators like butterfly and bees, and that many species of butterfly and bees have been harmed by destruction of habitats and city sprawl, it becomes clear how important this species is!  In addition, butterflies are beneficial to humans for their aesthetic qualities.  Many species are brightly colored and so capture the attention and marvel of many people.  Just watching the whimsical flight of butterflies is enough to lift the spirits!  The Checkered White, for example, has a fast and erratic flight pattern and likes to stay near the ground and in the open (4).

We had a visit from a female Checkered White butterfly this afternoon.  She checked out several flowers, including the whirling butterfly Guaras, purple moss Verbena and what seemed to be her favorite, the Copper Canyon Daisies.   Meanwhile, the large Black Swallowtail caterpillar has left the parsley, I assume to find a nice place to make its chrysalis before emerging as a butterfly in a couple of weeks.  The little guy, however, is still munching away on the parsley!