Washington State University Extension

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written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published- AUGUST 15, 2014


There has been much attention given to the devastating losses of honeybees in our country due to pesticide poisoning, mites, and more. Did you know that these valuable pollinators are not native to North America? The Western honeybee (Apis mellifera) was imported by European settlers who came to this country to farm in the 1600s. It was just one of the domesticated animals they brought along with them.

Honeybees create new colonies, increasing their numbers, with swarming behavior. Wild honeybees move out as a swarm from one colony to start a new colony. This swarming behavior was responsible for the honeybee migrating northward and westward from Virginia where they are first believed to have become established. By 1843 they had reached Kansas, then moved further westward when Mormons took them to Utah in 1848. Transporting hives by sea, a botanist introduced Western honeybees to California in 1853.

We have come to rely on the industrious honeybee for pollination of many of our commercial crops and are very concerned about the decline of both wild and domesticated Western honeybee populations. However we should not forget native pollinators, such as the over a dozen species of bumblebees in the Pacific Northwest. These large furry bees are also hard workers, helping to pollinate many of our fruit and vegetable crops.

Bumblebees nest primarily in underground cavities, such as abandoned mouse burrows. New nests are started by overwintering queens. Each queen starts a new colony by laying no more than six eggs in her new nest. These eggs hatch into sterile female workers who care for the queen, the additional brood she begets, and the nest.

Unlike much larger honeybee colonies, a bumblebee colony will have a maximum of a few hundred workers. At the end of the season the queen will lay both female and male eggs. These will hatch, emerge from the nest, and mate. The mated females become next year’s queens and find a protected place to spend the winter. All the other bumblebees in the colony, including the old queen, will die.

You must be familiar with the loud buzzing of bumblebees in the garden. You may think that this sound comes from the movement of their wings, but it is actually the rapid vibration of their flight muscles. They use these same vibrations to warm up their bodies to fly in cool weather, allowing them to fly earlier in the season and at lower temperatures than many other insects, including honeybees, can fly.

Like honeybees, bumblebees help with pollination by moving pollen from flower to flower as they work to collect nectar and pollen for feeding their colonies. However, they are also ‘buzz’ pollinators. The vibration of their flight muscles also vibrates the flower they are visiting. Some flowers are ‘self-pollinating’ and do not need a transfer of pollen from another flower. However, movement from wind or ‘buzz’ pollination is needed to shake the pollen off the anthers within the flower. Crops helped by buzz pollination include blueberries, cranberries, kiwi, eggplant, peppers, and tomatoes.

Bumblebees, honeybees, and many other native pollinators are at risk. As gardeners, there are some very simple things we can do to help, like planting a pollinator garden that includes native flowering plants. Avoid using insecticides in the garden. Learn more about our native pollinators so you can protect their habitat and make sure these extremely valuable natural resources are not lost.

Published: 8/15/2014 11:36 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
Published 2/22/2013

Honeybees in this country are disappearing at a frightening rate due to a problem labeled ‘colony collapse disorder’ or CCD. One-third of honeybees are lost every year in Washington and around the country.

If you’re a gardener and even if you’re not, this should scare you, especially if you like to eat. The USDA Agricultural Research Service estimates that bee pollination is responsible, directly or indirectly, for one out of very three mouthfuls of food in our diet. Many of the commercial tree fruit, berry, nut and vegetable crops grown in this country are dependent on honeybee pollination.

When CCD was first noted, beekeepers initially blamed pesticide use. Many of our commercial and garden pesticides are highly toxic to bees. Farmers and gardeners have been cautioned about using pesticides when bees could be present and urged to use chemicals only when necessary. However, the problem has turned out to be more complex and research is being conducted across the country to determine the possible causes of the CCD.

Early research associated CCD with the presence of Varroa mites, virus transmitting parasites, often found in hives decimated by the collapse disorder. Further research indicated that multiple factors may be at fault, including a pathogenic gut fungi called Nosema, and other unknown pathogens; Varroa mites; and stress. While you might think that honeybees are pretty ‘chill’ buzzing from flower to flower, some management practices and environmental conditions do impact bee and colony health.

Domesticated honeybees kept in manmade hives can be stressed by overcrowding and from being moved from location to location for pollination of commercial crops. Environmental stresses can include the limited availability of clean water, a scarcity and lack of diversity of pollen and nectar, and low nutrition pollen and nectar.

Exposure to pesticides, at both lethal and sub-lethal levels, is also a factor. This includes the pesticides beekeepers use to treat hives for control of Varroa mites. Insecticides, miticides, fungicides, and herbicides that bees are exposed to while out foraging build up in the wax of the comb over time. Because of this, experts now recommend that beekeepers change the combs more frequently.

Washington State University takes the problem of CCD very seriously. After all, honeybees are essential to most of the fruit and vegetable crops grown in the state. WSU’s Honey Bee Colony Health Diagnostic Laboratory is researching Nosema, the interaction between parasites and pathogens, and the effects of sub-lethal pesticide residues being found in hive combs.

What can gardeners do while researchers try to find the solution to the CCD problem? The Home Garden Seed Association recommends:

1. Planting flowers in clustered clumps at least four feet in diameter. They’re more attractive to honeybees and other pollinators.

2. Plant a variety of flowers that bloom at different times, so you’ll have flowers that provide nectar and pollen for the bees from spring to fall.

3. Avoid the use of pesticides, even those that aren’t highly toxic to bees. Try to manage pest problems without chemicals.

SIDEBAR REMINDER: Have spring fever? Want to learn about growing vegetables, square-foot gardening, raising geraniums, starting a backyard pond, growing blueberries, local xeric and alpine plants, and how take great garden pics? Attend the day long Spring Garden Day on March 9th sponsored by WSU Extension Master Gardeners. The keynote address ‘Grow Cook Eat’ by author Willi Galloway will be followed by a variety of exciting classes. The cost of the program is $20 per person. Call 735-3551 for information on registering.

Published: 2/22/2013 10:43 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I was over the moon with delight the other evening when a pair of gold finches visited the birdbath on my patio. I was sitting just four feet away and was amazed by this feathered duo alighting for a little drink from the birdbath I had refreshed just minutes before. I had hoped that this water feature in my garden would be more than just a decoration!

If you’re trying to encourage bird and insect wildlife in your garden, providing water in our hot dry climate is a definite advantage. While some species of birds get their water from the fruit and other plants they feed on, many species of birds need water for both drinking and taking a bath… thus the name “birdbath.”

I like the decorative aspect of a birdbath with the reflective surface of the water providing a note of tranquility to my patio and garden. However, large flat pot saucers or even an upturned garbage can lid can be used as alternatives to more expensive metal, stone, and pottery birdbaths, according to Margaret Brittingham, Associate Professor of Wildlife at Penn State University.

Whether manufactured or makeshift, Brittingham indicates that a birdbath should be no deeper than three inches in the center with the sides sloping downwards to the deepest point. She also notes that birds need an edge around the rim of the bath to serve as a perch. Smooth glass or plastic surfaces can be slippery, making it hard for birds to hold on. The edge should be rough or you can provide footing by placing flat stones near the edge of bath container.

Brittingham also notes that birds are attracted to dripping water, making birdbaths already plumbed and wired as a fountain ideal. Handy gardeners with a drip system can probably devise a little drip emitter for the bird bath.

The presence or absence of cats in your yard is an important factor when considering where to locate a birdbath. A birdbath can be placed on the ground, if cats aren’t around. If you have cats on the prowl, a bath should be elevated on a pedestal or stand of some sort. It’s good to locate a birdbath near a tree or shrub where branches provide the birds with a place to stop and preen before flying off. However, if cats are present, don’t place a birdbath next to shrubs where the cats could lay in wait.

It’s recommended that you keep your birdbath free of algae and prevent it from becoming a breeding zone for mosquitoes. In hot weather replace the water daily. To prevent the buildup of algae, scrub and rinse the bath basin at least once a week. Don’t use chemicals to control the algae. They can be harmful to the birds.

Birds aren’t the only backyard visitors that can benefit from providing a refreshing water source. Honeybees need water too! Experts recommend a large container as a “beebath” since bees find the water by noting the increased humidity above the area. Smaller containers don’t raise the humidity enough to get the attention of the bees.

Deep container like birdbaths can lead to bees drowning. You can prevent this by placing pebbles or small stones in a container and then adding water. The pebbles act as bee perches so the water shouldn’t cover the pebbles. An alternative to pebbles is providing floating surfaces, such as twigs or pieces of wood, in the water for the bees to land on. It’s also important to keep any “beebath” clean with fresh water and scrubbing.

If you don’t have a birdbath or a beebath in your garden, think about adding one. The visits of birds and honey bees are true delights!

Published: 6/27/2009 9:41 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

It was serendipity a week ago when I was at a WSU training conference and found myself in a class about bees… I had meant to go into a class on weeds. The topic of this seminar wasn’t honey bees or my favorite, the bumble bee. It focused on some of the other bees that can act as pollinators.

The class instructor started by pointing out that there are two main types of bees, social or more correctly “eusocial” bees and solitary bees. Eusocial bees form colonies with many workers that forage for food and rear the young. Honey bees and bumble bees are the best examples of the eusocial type. A good example of a solitary bee is the leaf cutter bee where the adult female bee builds her nest and provides for her own offspring.

In a way, leaf cutter bees are familiar to many home gardeners. The female of this little bee uses her scissor-like jaws to cut out pieces of leaf tissue for her nest. She is able to cut an almost perfect circular hole one-quarter to one-half inch in diameter from the edge of a leaf. She uses each circular piece of leaf to line her nest and create a cell where she will lay an egg. She fills the cell with collected pollen and nectar to nourish the “baby bee” or larva as it grows. Depending on the size of location she has selected for her nest, she will cut out more circles to create additional cells. The leaf cutter bee spends the winter as a pupa, then spins a cocoon, and emerges as an adult bee the next spring.

Leaf cutter bees seek out small holes or cavities in which to situate their nests. In the garden they like to nest in the hollow centers of rose canes created by borers or in the hollow stems of other plants. Rose leaves seem to be one of their favored garden plants for cutting out leaf circles for their nests.

There are a number of native leaf cutter bees, but the alfalfa leaf cutter bee, Megachile rotundata, is not native. It originates in Eurasia and has been used in the western U. S. for pollinating alfalfa grown for seed production. The leaf cutter bees are much more effective in pollinating alfalfa than honeybees or other types of bees. Perhaps its because they don’t mind the top lid of the alfalfa flower banging them on the head when they go in and out of the flower.

There are even bee “brokers” who raise leaf cutter bees for use in alfalfa seed production. These brokers create nesting boxes by filling a box frame with plastic drinking straws or by drilling lots of holes in styrofoam trays. The bees find these nesting boxes handy and will use them for laying their eggs instead of looking for plants. The bee brokers store these nests over the winter in a warehouse where they can control the climate. In the spring, they take them out in the field when alfalfa is in flower.

Leaf cutter bees are hard workers, even harder workers than honeybees. It only takes 150 leafcutter bees to do the work of 3000 honeybees! The adult bees are usually smaller than a honeybee and gray in color. They’re most active when the temperature is above 70 degrees Fahrenheit, working from early spring to late summer. While they will pollinate different flowering plants, they have a preference for the flowers of legumes.

A cousin of the leafcutter bee, is the blue orchard mason bee, Osmia lignaria. Much like leafcutter bees, the female mason bee finds holes already present in wood and uses them for her nest. The holes must be about one-quarter to three-eighths inch in diameter, just a little larger than the mason bee, which is a little smaller than a honey bee.

They get their name because they’re a shiny dark blue and from the way the female builds her nest, using mud to plaster the bottom of the hole. She then collects food, pollen and nectar and provisions the cell for the egg she than lays there. Next, she seals the cell with more mud and creates another cell, repeating the process until the hole is almost filled with cells. She finishes off the nest by sealing it with a mud plug.

Unlike the leaf cutter bee, the blue orchard mason bee lives a fairly short time, only about a month. During that time a female can produce about two eggs a day. The eggs hatch into larvae and are nourished by the food left in the provisioned cells. Each larva spins a cocoon and pupates in the cell, changing into an adult before winter. However, the adult stays in the cocoon and waits until spring to emerge when the weather is warm enough. The adult bee then chews its way out of the cell, mates, and the process starts all over again.

Mason bees have become a popular pollinator in home orchards. Gardeners construct mason bee “houses” to encourage their nesting. Many of these bee houses are constructed out of pine or fir cut lengthwise. Holes are drilled three to six inches deep in the wood to create nesting places for the mason bees. Some gardeners also use nests made of boxes filled with drinking straws, just like for the leaf cutter bees. The houses or nesting boxes are attached firmly to a structure in a location where the bees have been observed and hopefully they move in. This docile little blue bee is really quite amazing. It’s such a good pollinator, that it only takes about 250 mason bees to do the work of 60,000 honeybees. It gives new meaning to “busy as a bee”!

The alkali bee, Nomia melanderi, is a native solitary bee that’s been used to pollinate alfalfa and some other agricultural crops in our region. It gets its name because it nests in alkaline soil, preferring bare soil areas that stay moist, but not wet, most of the time. The females create cells in the soil about four to eight inches below the surface. While they are solitary bees, they tend to nest together in an area. Some alfalfa producers feel the alkali bees are the best alfalfa pollinators and have encouraged alkali bee populations by creating artificial nesting sites, but these are much more difficult to create than the nesting boxes or bee houses used for leaf cutter and mason bees.

Thankfully, one solitary bee that can’t be found in this region is the carpenter bee. These big bees “drill” their own holes or tunnels in wood for their nests. Their tunnels can be several feet deep. They prefer soft woods that have been painted or that are still covered with bark. While they do pollinate some crops in the areas they reside, they aren’t highly prized pollinators.

I’m glad that I accidentally attended this class. It gave me the chance to learn more about some little bees that I didn’t know much about before. Now you know about them too.

Published: 9/24/2005 11:39 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Well, the weather is cooling off a bit and there’s a definite chill in the air. I even had to put on a jacket the other night. The days are obviously getting shorter. These climatic cues tell us that fall… and then winter must be on the way. It’s these same cues that tell insects that they need to be thinking about how to survive the forthcoming cold weather . To be more accurate, they don’t really think about it, it’s part of their instinct to seek out protected places in which to overwinter.

Yellowjackets are one insect that can be troublesome and aggressive as fall and winter approach. The most common yellowjacket in our area is the western yellowjacket, Vespula pensylvanica. It’s a ground-nesting wasp that becomes more defensive of its colony as the nest increases in size over the summer. In the fall, these same yellowjackets become particularly aggressive as they scavenge for food. They’re a nuisance anyplace where there’s protein or sweet, sugary foods available, such as at picnics or around ripe or fermenting fruit on trees and vines.

Because yellowjacket nests are annual, the entire colony (except for the queens) will die out in the late fall with the onset of frost and cold temperatures. The queens spend the winter in a protected place, such under the siding on your house, beneath leaf piles, in compost piles, and within wood piles. In the spring, each surviving queen leaves her overwintering site and finds a new location for a nest and starts a new colony.

Sometimes those overwintering queens get lost and show up inside your house in the fall or on a sunny winter day. Make no mistake, while they may be sluggish and not very aggressive, they can still sting. Keep in mind that yellowjackets can sting you more than once. The best control when you see one in the house in the fall or winter is to carefully squash or vacuum them up.

Outdoors in the fall, the aggressive workers are quite beneficial in the garden. They eat countless caterpillars and other insect pests. However, they can be a hazard when you’re trying to have a picnic or even just sitting outdoors drinking a pop. It’s usually difficult to locate and safely treat yellowjacket nests. Your best bet to reduce the hazard they pose is to place yellowjacket traps at the perimeter of your property. Traps contain chemical attractants that lure the yellowjackets to them. The very best time to put out these lure traps is in late winter or early spring to get overwintering queens before they start new colonies. Used in the fall they can reduce the number of aggressive workers, but they don’t work well in controlling large populations.

Seed bugs are much more benign fall pests than the belligerent yellowjackets. That’s because they don’t sting. During the summer and fall, different types of seed bugs feed on the seeds of specific plants. The prolific boxelder bug feeds on the seeds of boxelder trees and other types of maples. There is a little gray brown bug that feeds on sage brush and there’s even a smaller tan bug in the area that feeds on the tiny seeds of birch trees.

Seed bugs are not generally considered plant pests since they don’t hurt the plants on which they feed, but they can become a nuisance when they’re present in the yard in large numbers or when they migrate indoors in the fall looking for a place to overwinter. Indoors they don’t attack food or furnishings, but their presence is objectionable to many folks, especially since some bugs give off an unpleasant odor.

Seed bugs find their way indoors through small openings in vent screens, gaps between window and door frames, holes for plumbing and cables, and under siding. It’s always a good idea to seal up your home as tightly as possible to keep out unwanted guests, such as seed bugs and spiders, and to conserve energy. If you have tried to tighten up your house, but you still have an influx of bugs, your best bet is to vacuum them up and then dispose of them in a garbage bag.

If you’re overwhelmed by seed bugs outdoors, insecticidal soap does a terrific job of killing bugs. The only problem with the soaps is that they have no residual activity and need to be reapplied when new bugs come into the area. Insecticidal soaps are considered much kinder to the environment and safer to use than older chemical pesticides.

Spiders are other creatures that find their way into homes in the fall. The majority of spiders are not poisonous and should not cause undue concern. Outdoors, spiders should be considered beneficial, as they eat other insects. Indoors, most of us don’t want to tolerate their presence so the vacuum or a good smack with a newspaper is an effective method of control.

However, there is one spider that can be worrisome. It’s the hobo spider, Tegenaria agrestis, (formerly known as the aggressive house spider). Fall is mating time for the hobo spider and the male hobos go in search of female hobos. In their mating quest, the male hobos sometimes enter homes, usually at the ground level or below. Hobo spiders prefer the outdoors, usually building their webs in moist, cool spots, such as in grassy areas and woodpiles.

The hobo spider has a venomous bite that is often mistaken for the bite of a brown recluse. The severity of a bite varies, depending on the person and depending on the amount of venom injected by the spider. Spider experts believe that at least half of the home bites are “dry,” meaning no venom is injected. A “bad” hobo bite results in blistering at the bite site, followed by ulceration, and then skin necrosis. A bad bite can take from a month up to two years to heal.

Of particular concern in the fall are those sex-driven hobo males, who tend to have a more toxic bite than the females they seek. Again, it’s important to tighten up your house to prevent the entry of spiders and unwanted insect guests in the fall. Wear long sleeves and gloves when moving wood, lumber or other debris in the garden where the hobo spiders might be lodging. Also, observe particular caution when vacuuming or squishing these spiders.

Want to learn how to identify a hobo spider ? Go to:

Published: 9/17/2005 11:39 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

My youngest son graduated from high school last week so things were pretty busy around our house, but I took time one evening to quietly sit outside and watch the birds and the bees. The quail were chattering and the magpies were squawking away. Sitting next to a big planting of sage in bloom, I was in the perfect spot to observe the insects buzzing about the flowers.

Most obvious were the black and yellow bumble bees noisily collecting nectar and pollen. What amazing creatures! I can remember a long time ago in elementary school when one of these huge hairy bees found its way into the classroom on a sultry day when the windows were wide open. They created quite a stir, seeming to dive bomb us panicking students who didn’t want to get stung. We didn’t know that while female bumble bees are capable of stinging, they’re not very aggressive and generally won’t bother you unless you venture near their nest.

Bumble bees seldom sting while foraging for pollen in the flower garden. If you do instigate an attack by threatening their nest, the female bumble bee can sting repeatedly. Since they’re docile when visiting the garden for pollen, it’s not too hard to get a close-up look at them. If you dare to take a peek, you might be able to see a pollen basket stuffed with pollen on each of the bee’s hind legs.

Like honey bees, bumble bees are a highly social insects. They live in colonies made up of a queen, female workers, and males. Unlike honeybees, their nests are annual, lasting for only one summer. Fertilized queens are the only members of the colony to survive the winter after hibernating in the soil. A new nest is started in the spring by an individual queen. She normally looks for an unoccupied rodent burrow or bird’s nest in the ground, but may sometimes find a suitable site in a wall void, wood pile, tree cavity, or in pile of brush, rubbish, or yard waste.

This queen will line the space for the nest with grass or moss and go about collecting pollen and nectar to feed her first brood. This first brood is comprised of all female workers who take over the duties of collecting food, caring for the developing bee larvae, and managing the nest. The queen is then able to focus on laying eggs throughout the summer. In late summer, reproductive males are produced and these mate with the queens to produce the fertile female queens that will survive the winter by hibernating in the soil or a protected spot. The males and female workers die with the cold weather.

With only annual nests, bumble bee colonies don’t grow to the large numbers of honey bee colonies. By the end of the season there will most likely only be a couple hundred bees in the nest. They also differ from honeybees in that they don’t store a surplus of honey, but they do collect nectar and pollen and store it in cells made from wax and pollen.

Bumble bees are definitely our garden friends. They’re excellent pollinators of flowers, fruit, and vegetable crops. With the decline of wild honeybee populations, they should definitely be protected from harm as much as possible.

As I sat and watched the bumble bees enjoy the nectar of the sage flowers, I noticed some smaller creatures resembling honey bees visiting the flowers too. I recognized these bee-impersonators as syrphid flies, also known as hover flies or flower flies. At first look they simply look like honeybees with their black and yellow banded abdomens, but a closer look will reveal that they’re imposters. They only have two wings, where bees have four. Their antennae are stubby little things, where bees’ antennae are long. Flies have those notorious compound eyes and bee eyes are simple.

The epithet of ‘hover fly’ refers to their ability to hover in one place and then move quickly sideways, backwards, or forward and then stop and hover again. They’re also known as ‘flower flies’ because they feed on the pollen and nectar of flowers. Even if they aren’t a bee, these flies are important pollinators.

Syrphid fly adults are our friends because of their pollinating activities, but they also do double duty for us in the garden. Their larvae (maggots actually) feed on aphids and other soft-bodied insects. The adult flies lay their eggs individually on aphid infested plant leaves. These eggs hatch into maggots. The maggots are green to brown with whitish markings and a pear-shaped tapered body.

The sluggish maggots are blind so they must wiggle around on the leaf, tapping their head until they find a juicy aphid. They then latch on to the aphid with their mouth hooks (at the narrow end of their body) and suck out its body juices. They feed for a week or so, dining on as many as 400 aphids, and then drop to the ground and pupate in the soil. They later emerge as adult flies and begin laying eggs again. Each female can lay several hundred eggs during the summer. Depending on the type of syrphid fly, the location, and the weather there can be three to seven generations per year.

To see what some of the most common northwest syrphid fly adults look like, go to these two sites on the web:

What a pleasure it was to slow down a bit and sit out in the garden. Take the opportunity sometime soon to sit out in your garden or visit the Master Gardener Demonstration Garden next to the Mid-Columbia Library at 1620 S. Union in Kennewick. If you look closely, you’ll probably see bumble bees, syrphid flies and a variety of other insects and wildlife… and you’ll definitely see lots of pretty flowers.

Published: 6/11/2005 1:40 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Trying to have a relaxing picnic in your backyard, a campground, or a park at this time of year can be downright dangerous because of the large yellow jacket populations foraging for food. I was at a backyard picnic last week where yellow jackets destroyed any thought of having a relaxing lunch outdoors. Everyone was worried about getting stung by these aggressive creatures. They particularly seemed to like the fried chicken. (I can’t blame them, it was good chicken.)

Many of the folks at the picnic were calling these obnoxious creatures “bees.” They weren’t bees. Honey bees are hairy little yellow-gold to yellow-brown creatures that subsist exclusively on flower nectar and pollen. They’re not considered an aggressive insect, but they will defend themselves or their colony if threatened. Most bee stings occur accidentally, such as when you put your hand or bare foot on top of one. This fight to defend themselves is a “fight to the death” because honeybee stingers are barbed. When they sting, their stinger is left behind in your skin and the bee dies.

Yellow jackets are a type of wasp and quite different from bees other than they can both sting humans. The most common yellow jacket in our area is the western yellow jacket. It’s part of a ground-nesting family of yellow jackets. The western yellow jacket is hairless and colored black with bright yellow band markings. The western yellow jacket is sometimes called the “meat bee” (It’s not a bee!) because it feeds on meat. As a rule, wasps feed primarily on other insects or other animal protein food sources with some exceptions. Yellow-jacket stingers are not barbed, enabling them to sting repeatedly without harm to themselves.

Western yellow jackets are a problem almost every year during the late summer and early fall. There’s several reasons for this. First, their population has been increasing in numbers since one overwintering queen founded the nest by laying eggs early in the spring. One nest started by one queen may have as many as 5,000 workers by the end of summer. These workers are the ones foraging for food.

If their large numbers weren’t enough to make them a nuisance, their increasing aggressiveness makes them obnoxious and potentially dangerous. They become so aggressive because they’re hungry. As their nest was growing, the job of the workers was to forage for protein and feed it to the larvae. In return the larvae secreted a sugary material that the workers ate. In late summer the production of new larvae ceases and this multitude of workers crave their “sugar fix” but aren’t able to get it because of the dwindling number of larvae. As a result, they become quite bold and belligerent in finding alternate sugary foods… and picnics are a surefire banquet for them, especially ripe fruit, soft drinks, and other sweet stuff.

Fall is here and multitudes of yellow jackets are here too. How can we control them now? Quite simply we can’t. There are some actions that we can take to protect ourselves from them, but control is pretty much out of the question at this time of year unless you can locate their nests. My first word of advice is don’t swat at them… like everyone at the picnic I attended was doing. This can incite them to protect themselves by stinging you. You do best to stay calm and unmoving, and then after a bit move slowly away. (I realize that this is almost impossible advice to follow!)

To minimize the attraction of yellow jackets to your picnic, leave food, especially fruit and sugary drinks, covered until the group is ready to eat. Throw leftover picnic fare into well sealed trash cans. In park or fair situations, dumpsters should be cleaned daily at this time of year to reduce the food they provide for foraging yellow jackets. Be aware that after you’re done eating and all the food is stored away, the yellow jackets will stay in the area and continue to look for those tasty goodies that attracted them to the area.

If you grow fruit in your garden, remove and dispose of fruit when it ripens… if you don’t plan on eating it. Yellow jackets seem to especially like ripe grapes in both home and commercial vineyards in the fall.

There are also special lure traps available for yellow jackets. They are most effective when used in the spring when the overwintering queens first emerge and before they start building nests. The more traps set up to catch those queens, the greater chance of reducing worker populations at the end of summer. The lure traps are not very effective in reducing large worker populations at this time of year, so be sure to start early in the spring. Follow label directions regarding how to use them effectively and how often you need to renew the chemical attractant.

When not attacking us at picnics or in our gardens, yellow jackets are considered beneficial insect predators eating a variety of caterpillars, flies, and grubs.

Published: 9/8/2007 2:36 PM



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