Friday, June 25, 2021

A Wasp-Benefit Analysis – Part II: Social Wasps

By Lisa Mason, Arapahoe County Extension 

In case you missed it, click here to read Part 1. We covered the purpose of wasps in the ecosystem and answered questions on the Asian giant hornet that made headlines in 2020. Part II will cover social wasps, their role in the ecosystem, and possible control methods if they become a nuisance.

Wasps sometimes get a bad reputation because they can sting and are sometimes a nuisance. We have one species of wasp that can be particularly aggressive: the western yellowjacket. Don’t let one or two species of nuisance wasps ruin your opinion of all wasps. Wasps are a diverse group of insects that provide important ecosystem services such as pest control.

Social Wasps

Social wasps are probably the most familiar wasps to people because they are easily seen in the yard and landscape. Social wasps live in a colony together. They have a similar lifecycle to a bumble bee (Bombus spp.).  A new colony is started each year by a fertilized queen that survived the winter. She will lay several generations of female workers throughout the season. Towards the mid-to-end of the summer, she will lay eggs that are male wasps and potential queens. The males and potential queens will leave the colony to find a mate. Once cold temperatures arrive, the current colony will die except for the newly mated queens.

The cycle will repeat and the following spring, when the new queens begin a new colony. Social wasps always build a new colony each year. They never reuse old nests, which is important to note if you’re looking to control nuisance wasps. Social wasps make their nests out of chewed up wood, creating a paper nest. Social wasps also feed on insects like caterpillars, providing important pest control in our backyards. The western yellowjacket is a scavenger feeding on carrion and human sources of food such as trash.

Let’s discuss five species of social wasps that are found in Colorado. Understanding the life history of social wasps can help you control them if they become a nuisance in your landscape, and build appreciation for their complex social biology, along with the pest control services they provide.

A western yellowjacket. Photo: Lisa Mason

Western Yellowjackets

Western yellowjackets (Vespula pensylvanica) are a native, social wasp that you will find at your family BBQ, picnics, trash cans, etc. They are very common in urban landscapes and can become a nuisance. Like social wasps, they create a new colony each year. The paper comb nest is usually underground or in a cavity that is well-protected. While yellowjackets are commonly seen, their nesting site can be difficult to find.

Yellowjackets can be aggressive, especially when defending their nest and are responsible for 90% of the insect stings in Colorado. They are scavenging insects feeding on carrion, dead earthworms, garbage, human foods including meats, and sweet, sugary foods. They also will feed on honeydew, a sweet substance excreted by aphids and soft scale insects.  Scavengers are the clean-up crew for ecosystems and play an important role in the food web. Yellowjackets tend to get more aggressive in the fall as food can be harder to find.

If yellowjackets tend to be a nuisance in your landscape, you can purchase a yellowjacket trap available at hardware and garden stores. The traps contain heptyl butyrate which yellowjackets are attracted to. Traps will be most effective if they are placed outdoors in the early spring to capture the overwintering queens before they start their new colonies. Nest removal can be a dangerous task and difficult because their nests are so well-protected. Insecticide treatments often aren’t effective because it is difficult to get the insecticides inside the colony. Hiring a professional is often necessary. Remember, the colony will only last for one season. 

An underground entrance to a western yellowjacket nest. Photo: Nancy Bonita

European Paper Wasps

European paper wasps (Polistes dominula) are much less aggressive, but they often build their nests close to human activity. They are a non-native insect that has become well-established in Colorado. They first appeared in Colorado in the late 1990s/early 2000s. They prey on caterpillars and other insects and feed their young live insects. Common prey includes hornworms and cabbageworms. They also will feed on honeydew secreted from aphids. The papery comb nests are often found under house eaves, overhangs, sheds, pipes, and other hollow spaces in human infrastructure. 

If the paper wasp nest is located in an area that won’t be disturbed by people, the nest can be left alone, and the wasps likely won’t be a nuisance. The current colony won’t survive when temperatures cool in the fall. If the nest is close to human activity, there are insecticide treatments to destroy the nest. Following instructions on the insecticide label is critical. Insecticides should be applied at night when most wasps are present at the nest. The nest should be destroyed afterwards to also kill the capped larvae in the nest. The location of the nest site should be thoroughly washed to prevent any remaining wasps from building a new nest.

Traps that attract yellowjackets will not attract paper wasps. There are no effective trap methods for paper wasps.

A European paper wasp. Photo: Lisa Mason

Baldfaced Hornets and Aerial Yellowjackets

Baldfaced hornets (Dolichovespula maculata) and aerial yellowjackets (Dolichovespula arenaria) are common in Colorado but are less likely to be a nuisance around human activity. They are only aggressive when their nest is threatened. They develop a large papery comb nest usually high in large trees and shrubs. They feed on caterpillars, other insects, and honey dew. If you find a nest in your tree or shrub, it may look intimidating, but the nest can likely be left alone if the nest can be left undisturbed. These two wasps can be common visitors in our landscapes but often go unnoticed by people.

A baldfaced hornet nest. Photo: Joe Boggs, Ohio State University Extension

A baldfaced hornet. Photo: Joe Boggs, Ohio State University Extension

Western Paper Wasp

The western paper wasp (Mischocyttarus flavitarsis) is a native paper wasp in Colorado and the western US. They have a similar biology to the European paper wasp. They are capable of building paper nests close to human infrastructure and activity, but they are not nearly as common as the non-native European paper wasp. They can sting if their nest is threatened, they often prefer to “ram” into the person or animal that is threatening the nest (Snelling, 1953). Like other paper wasps, they prey on caterpillars, flies, and other pests, bring the prey back to the nest to feed the young wasps the live insects. Adult wasps may also forage for nectar on flowers.

A Note About Insect Stings

Western yellowjackets are responsible for 90%+ of all stings in Colorado. When someone says, “I was stung by a bee,” they were likely stung a yellow jacket.

Both bees and wasps can sting. A stinger is a modified ovipositor (the egg-laying mechanism in insects), so only females have the ability to sting. The purpose of a stinger is defense, and in some species, predation. Generally, insects will only sting if they are provoked or their colony is disturbed.  Both social and solitary wasps and bees can have the ability to sting, but social insects are more likely to sting because they need to protect their colony.


Honey bees prefer to forage on flowers and go about their business in their hive, but they can sting if they need to protect their hive. Honey bees can sting only once. They have a barb at the end at the end of their stinger that stays in your skin. The barb is attached to the internal guts of the bee, so when the bee tries to fly away, the guts are ripped out of the bee’s body, which kills the bee.

Bumble bees have the ability to sting but will only sting if their colony is disturbed. They can also sting more than once unlike honey bees. Bumble bees are not aggressive and prefer to forage on flowers and go about their business. Many native bees are not able to sting or will only sting if handled.


Wasps can sting more than once. Solitary wasps will only sting if they are pressed up against your skin, or you try hard to provoke them. They prefer to fly away and stay away from human activity. Social wasps can be very defensive if their nest is disturbed. They also can sting if they are away from their nest and provoked. The western yellowjacket is much more likely to sting because they are scavengers and attracted to human foods and garbage. They tend to get more aggressive in the fall when temperatures cool down and food is harder to find. Other social wasps including the European paper wasp are generally not aggressive unless their nest is disturbed. The European paper wasp tends to build nests close to human activity on buildings, sheds, and other structures, which can increase the chance of nest disturbance.

Learn More

Western yellowjackets and European paper wasps can be a nuisance to people and often attract attention, but these wasps and other social wasps represent a small part of wasp diversity. Look for a future post about solitary hunting wasps. These wasps often go unnoticed in the landscape, but provide valuable pest control services! 

Friday, June 11, 2021


By Yvette Henson, San Miguel Basin, CSU Extension

Colorado has a semi-arid to arid climate with recurring periods of drought.  Yet, plants in the landscape provide many benefits like cooling the air temperature around and inside our homes.  There are also physical and mental health benefits from growing gardens.  Growing at least some of our own food contributes greatly to food security.  So, how do we use water responsibly to grow a garden, without waste?  

This blog posts gives some tips to conserve water in the vegetable garden: 

·         Grow only what you need.

·         Group plants with similar water needs.

·         Plant in blocks, not rows, to shade the soil.

·         Incorporate organic matter into soil before planting to hold water.

·         Apply mulch, after planting, to reduce evaporation.

·         Cover plantings with row cover fabric to reduce evapotranspiration.

A freshly watered vegetable garden. This garden will benefit from an application of mulch to the fall peas to reduce evapotranspiration.

Some other water conservation ideas to investigate are Hugelkultur, planting in natural depressions and paths of runoff (“rain gardens”).  Or you can create your own depressions, swales, and underground trenches to direct water.  Check water law before creating ponds or other larger water holding/directing structures.

“waffle gardens,” depressions in the ground hold water for crops, and were used by first nations peoples in the southwest. (Photo credit: Jodi Torpey)

When watering your garden:

·         Water only when needed, rather than on a schedule.

·         Use a trowel or shovel to check soil moisture, rather than guessing.

·         Water more deeply, to depth of the root zone, less frequently.

·         Water slow-draining soils, like clay, in several short intervals to reduce runoff. 

·         Water during the coolest times of day or when your garden is shaded.

·         Don’t water when it is extremely windy.

·         Don’t water automatically when you’ve received adequate rainfall (> ½”)

·         Use soaker hoses or drip irrigation.

·         Use harvested rainwater (see this Fact Sheet )

In general, water is most critical during the first few weeks of development, immediately after transplanting, and during flowering and fruit production.  Young plants need less but more frequent watering.  Older plants use more water but need it less frequently.  They have deeper roots and larger canopy. 

You can target the timing and amount of water to add during the most critical periods of each specific crop.   

Root crops need water most when roots are sizing up.  Water stress can cause bolting and/or strong flavor.  Fruit- and seed-bearing crops need extra water when fruit is setting and filling.  Too little water can reduce yield significantly but can also make fruit more flavorful.  Too much water before fruit set can delay it. Bulb crops, like onions and garlic, need more water when young and less water when maturing and none when curing (in ground).

Certain plants require more water than others.  Are they worth it?   For example, beans and strawberries (especially when establishing) need 0.25 to over 0.50 inches of water per day when blooming and setting fruit. Of course, this is variety dependent. Certain beans, like terpary beans, do not require much water.


Follow your local water restrictions, garden responsibly and reap the benefits!

Friday, May 28, 2021

Composting Considerations

By Denyse Schrenker, Eagle County Extension

I have a confession: I used to put grass clippings, leaves and yard waste in the garbage. Why did I waste all those great sources of organic matter? Why?!? Because it was easy and that’s what we did growing up! While I have not convinced my parents to start a compost pile, I have at least convinced them to leave their grass clippings on the lawn - a step in the right direction. What’s with their aversion to composting? Although composting is a fantastic way to convert our yard waste and some kitchen scraps into a great soil amendment and keep organic material out of our landfills, it can seem like a daunting and complicated procedure that requires a degree in organic chemistry to get right.

Home composting can be a simple and easy process, and I promise no knowledge of organic chemistry is required. A quick internet search of home or backyard composting (don’t forget the :edu!) will give you a plethora of great resources on how to compost at home. Composting in Colorado is the same as anywhere else but there are a few considerations we need to give more attention.

Office compost pile

Dry air & low rainfall

The organisms that are decomposing the compost materials need water to live. When parts of your compost pile dry out those microorganisms die and decomposition slows or stops in those parts until water has been added and they have had time to rebuild their populations. Water your dry brown (carbon) layers when you add them to your pile and water the pile regularly.

Your compost pile should be damp but not soggy. If you have a compost bin that is made of wire, you may notice that you have a hard time keeping the exterior of the pile from drying out. You can line the bin with plastic, or cover the pile with plastic, a tarp, or cardboard to keep the pile from drying out. Bins made of wood, plastic, metal or brick/concrete blocks will keep the pile more evenly moist and not dry out as fast.

Even with bins made from these materials you may still want to cover the pile. If you cover the pile with a tarp or plastic, try to place the bin where it will be partly shaded during summer or uncover the pile on hot days. Temperatures exceeding 160℉ will cause the decomposing organisms to die. I highly recommend buying a compost thermometer so you can monitor the temperature of the pile. They are around $20 and widely available online or in hardware and garden supply stores.  

Cold winters

Our cold winters make it hard to keep backyard compost piles active during winter which extends the time it takes to reach a finished product. Do not turn your pile after November in the mountains, to retain heat and keep the process going as long as possible. In the spring turn the pile and mix in fresh materials to reactivate the process.

I also suggest removing your finished compost at the end of the summer/beginning of fall so you have an empty or nearly empty bin. You can add the finished compost to your garden in the fall or wait and add it in the spring. I like to add the finished compost in the fall but wait to incorporate it until the spring, that way it acts like a mulch covering any bare soil over winter. Add your fall yard waste to the empty bin and continue to add your food waste to that bin over winter. In the spring add a brown layer (carbon source) and mix the pile. Bins made out of a more insulating material such as wood will also help prevent heat loss and keep the pile active longer into winter. Larger piles will retain heat better and stay active longer as well.


We live in close contact with our wildlife neighbors, especially in the mountains. Animal pests create another composting challenge. Animal products such as meat, dairy, bones, egg yolks and fats can attract unwanted critters so do not add those materials to your compost. You might want to avoid adding peanut butter as it attracts animals as well. If you are having a hard time keeping rodents out of your wood compost bin you can line it with hardware cloth. Cover fresh kitchen scraps with a carbon layer or bury them in the pile. Covering the pile with plastic, a tarp, or cardboard will help keep animals out as well - be sure to secure the cover. You might even want to make a lid you can secure over your compost bin to keep larger animals out.    

Basic Compost Troubleshooting




Compost stinks like rotten eggs

Lack of air - either too wet or too compact

Turn the pile or fluff it well and make sure it is not soggy wet.

Compost stinks like ammonia

Too much nitrogen

Add carbon source; dried leaves/plant material, chipped woody material, sawdust, wood chips, hay/straw.

Materials will not decompose

Pile is too dry, too small, or particle size too large

Check if the pile is dry - water regularly and cover if outer inches of pile consistently dry. Add more material and mix in with old material. Shred/chip large materials. 

Pile is damp and smells sweet but will not heat up

Not enough nitrogen

Add nitrogen source & mix well: grass clippings, fresh plant material, coffee grounds/veggie kitchen scraps, bloodmeal, fertilizer, manure from herbivore. 

Pile is only damp and warm in the middle

Pile is too small

Add more material and mix in with the old material

***If you add manure as a nitrogen source it should be from plant eating animals and you need to let the compost cure for 6 months to reduce pathogens if you want to use it in a food garden. Pathogens may still be present even after the curing process so wash all fruits and vegetables thoroughly and follow safe food handling practices. 

Do not add:

Meat, dairy, bones, oils, fats, human or pet feces, plants treated with weed killers, diseased plants, weeds that have gone to seed, wood or charcoal ash, highly resinous wood & leaves (junipers, pine, spruce, arborvitae), large amounts of leaves high in tannins (oak, cottonwood)

For more information check out: 

Fact Sheet 7.212: Composting Yard Waste

PlantTalk Colorado 1613: Composting

Friday, May 21, 2021

Another of My Favorite Native Flower Tufted Evening Primrose (Oenothera caespitosa)

 By Ed Powers, Jefferson County Master Gardener

The Tufted Evening Primrose caught my attention when I moved into my Evergreen home.  My south-facing hillsides have a number of these plants. We tried to repot them and read that Evening Primrose is available as potted plants or seeds from many sources. 

They require moderate watering to keep it blooming all summer. Soil should not be heavy and must have good drainage.  However our potted plants did not survive.  So I decided the best way is to take care of them on the hillsides.  Which we do.  

I did some research on them and this some of the information I found.  I used background information from Garden Notes of Colorado State University.

Tufted evening primrose or Oenothera caespitosa, is known commonly as tufted evening primrose, desert evening primrose, rock-rose evening primrose, or fragrant evening primrose. It is a perennial plant of the genus Oenothera, native to much of western and central North America which includes Colorado.  

It is a low-growing stemless perennial with gray-green fuzzy leaves and wonderful 3-4 inch fragrant white flowers that open in the evening and close in the mid-day heat. It grows in sunny, dry, infertile, rocky, well-drained soils.  This plant is showy, and requires little water, which makes it a perfect candidate for western xeriscape gardens.

As the name implies, this family has many species that bloom in the evening, the flowers stay open all night, and then wilt the next day. The flowers are usually white or bright yellow and attract large night-flying insects like hawk moths (family Sphingidae). 

In the evening-primrose family, the flowers often have a long floral tube that holds the petals well above the base of the flower. Nectar collects in the base of the tube so only long-tongued visitors can get a nectar reward. Again, hawk moths with their long coiled tongues are perfectly adapted to reach the nectar in evening-primrose flowers.

Friday, April 30, 2021


By Cherie Luke

Rheum rhabarbarum, commonly know as rhubarb, originated in China and the Himalayas. It is a true harbinger of spring! Botanically it is a vegetable because we eat its stems and not its fruit, but it is used like a fruit in pies, tarts, crisps, and even in wine making. 

Rhubarb crowns are best planted in early spring or late fall in well drained soil with plenty of organic matter. In a sunny location in your yard, dig a hole so the crown buds are 2-3 inches below the soil surface. Rhubarb plants need plenty of space to grow, so plant them 4-6 feet apart. 

Rhubarb emerging in spring

Mulch plants with compost to provide nutrients and to retain moisture during the summer. Keep your rhubarb patch free of weeds so it will not likely be disturbed by diseases or insects. The first year you should let the rhubarb grow without harvesting any of the stalks so your plants can become established. The second year, if the plants show vigorous growth, you can harvest a light crop. By the third year you can harvest most of the stalks. 

The leaves of rhubarb contain the toxin oxalic acid and should be kept out of reach of children and grazing animals. The leaves can be composted without any danger. Rhubarb can live for 15 years or more with little attention but will benefit from a top dressing of compost or rotted manure in fall, and also by occasionally dividing the roots. If seeds stalks appear they should be removed so the plants can focus their energy elsewhere. 

Rhubarb requires two months of freezing temperatures to break their rest period. Rhubarb like a long cool spring, which makes it an ideal plant for mountain gardens. It is hardy in zones 3-8. 

CSU has a short video on how to harvest your rhubarb. #rhubarb

Friday, April 16, 2021

Watch Your Woody Plants for Damage Caused by Environmental Stress

By Kristina Hughes, Clear Creek County Master Gardener

In spring of 2020 I noticed my hawthorn, lilacs and roses were struggling. They leafed out much later than usual and were growing very slowly. My neighbors were having the similar issues with their woody plants. There was much more winter dieback than usual, even on native plants.


I consulted the Plant Diagnostic Clinic and learned that the damage was a result of the sudden, extreme freeze that had occurred in April 2020, a few months prior. There had been a warm spell and the plants had started to leaf out, then the temperature plunged more than 40F. The first round of growth and buds had frozen. The plants then tried to push out leaves again later in the spring, but by then it was very dry. Plants need water to fill out their expanding leaves and there wasn’t enough water in the soil at that time for the plants to fully expand the second set of leaves. I realized that if the plants were stuck with stunted leaves for an entire growing season they would only generate a fraction of the energy that they would normally make in a season. The entire plant would be weakened the next year.


So I followed the advice of the Plant Diagnostic Clinic and watered my woody plants very well. It took a concerted effort to water by hand until the entire root zone down 12”-18” was moist. But I did it quickly and I watched my plants expand their leaves to full size. I knew they would have a fighting chance of recovering from the freeze damage. 


Late frost damage. Photo by Dana Ellison.

I bring this up now because stress to woody plants can take a long time to show up. The damage done during the extreme freeze of Easter 2020 can continue to appear during this growing season. This year we’ve had a dry and warm winter which has added more stress to the plants, so I’m going to continue to watch my woody plants closely this year and make sure they have enough water if they look like they’re struggling.


For more information on freeze damage:


Jeffco Clinic’s Top 10 Plant Problems of 2020


Environmental Disorders of Woody Plants (sections on drought and freeze damage)


Jefferson County Plant Diagnostic Clinic diagnoses samples for a small fee

Friday, April 2, 2021

High Altitude Natives

By Sandy Hollinsworth, Gilpin County Master Gardener

Increasingly, mountain gardeners and homeowners living above 8,000 feet are interested in landscaping with native plants to increase success and promote sustainable, natural habitats. Native plants are inviting to pollinators, birds, and mammals by providing food, shelter, and nesting material. There are many benefits to using Colorado native plants including biodiversity, beauty, adaptability, plus many are fire-wise plants. They are naturally adapted to Colorado’s climates, soils, and environmental conditions. By choosing native plants, gardeners can work with nature, rather than trying to grow plants that are not suited to our local high-altitude conditions. Native plants are also more resistant to pests and disease when grown in areas where they are found in nature.

The mountain region is characterized by short growing seasons, cool nights, strong sunlight, and high winds. The soils tend to be decomposed granite, low in organic matter, and are usually very well-drained. Many native plants prefer particular soil textures, whether sand or clay or loamy soils. Almost all high mountain natives do not last as long in enriched garden soils; they grow faster and may look fabulous for a few years then die sooner. Because native plants are adapted to native soils they will thrive without fertilizer or soil amendments. A small amount of compost may help work the rocky soil, but gardeners will benefit by using compost sparingly. Species like columbines and Jacobs ladder that grow in moist forests, may benefit from more compost but otherwise, plant natives without fertilizer and other amendments.

Another consideration is microclimates, sections that are hotter and drier, or cooler and wetter than the rest of the property. Every garden and property have microclimates, depending on shade, sun, slope, water, and wind protection. Grouping plants with similar sun, water, soil and protection requirements will add to success and help with supplemental watering as needed. Colorado mountain natives generally require less water unless they naturally grow in riparian areas like Bluebells, Parry’s Primrose, Scouring-rush Horsetail or Blue-Eyed Grass.

Maintenance in your garden may be easier with natives. It is recommended not to rake away all dead leaves and twigs as it helps protect the soil and offers protection to overwintering pollinators. In fall it is best not to cut back plants but instead to leave seed-heads and dead stalks for food, perches and winter homes for native bees, beneficial insects, and wintering songbirds. Wait to cut back dead plant stalks in early spring at the first sign of green-up.

Mulch is critical for starting native plants from seed, and it can be a huge help in establishing nursery-grown plants too. Gravel mulch is best for retaining soil moisture without causing crown or root rot. Next best is locally-sourced shredded bark mulch although it can blow away.

Non-native plants that are adapted to Colorado’s climate, including CSU Plant Select species, may be more readily available. In years with less than normal rainfall and snow these non-native plants may need supplemental water, again pointing out the adaptive advantage of native species. Gardening with native plants also prevents the introduction and spread of noxious weeds. Many noxious weeds were intentionally introduced as garden plants and can crowd out or change the garden’s native characteristics.

In Gilpin County, the following list of native plants are found at 8,500 – 9,500’ on nature hikes and in established natural habitats. Most are available at local native oriented nurseries or through CSU Extension native plant sales. Inquire about sun and water recommendations to make sure to plant the right plant in the right place. Seedlings will take a few years to fully establish. Some reseed freely while others stay put and grow to their mature spread and height over time. Wind, furry critters, birds, and domestic animals may help spread seeds.

Pussytoes Antennaria spp

Kinnikinnick Arctostaphylos uva-ursi

Sulfur Buckwheat Eriogonum umbellatum

Common Yarrow Achillea millefolium (lantana)

Nodding Onion Allium cernuum

Pearly Everlasting  Anaphalis margaritacea

Fringed Sage   Artemisia frigida

Fringed Sage Artemisia frigida

Rocky Mountain Columbine Aquilegia caerulea

Blue Grama grass Bouteloua gracilis

Harebell Campanula rotundifolia

Indian Paintbrush Castilleja spp.

Rocky Mountain Bee Plant Cleome (Peritoma) serrulata

Showy Fleabane Erigeron speciosus

Wallflower  Erysimum capitatum

Blanketflower  Gaillardia aristata

Richardson’s Geranium Geranium richardsonii

Sticky Geranium Geranium viscosissimum

Prairie Smoke Geum triflorum

Sneezeweed Helenium  Hymonoxys hoopesii

Showy Goldeneye Heliomeris (Viguera)

Scarlet Gilia Ipomopsis aggregata

Rocky Mountain Iris Iris missouriensis

Blue Flax Linum lewisii

Silvery Lupine Lupinus argenteus

Bee Balm/Horsemint  Monarda fistulosa

Showy Locoweed Oxytropis lambertii

Rocky Mountain Penstemon Penstemon strictus

Blue Mist Penstemon Penstemon virens

Silky Phacelia  Phacelia sericea

Jacob’s Ladder Polemonium viscosissimum

Pasque Flower Pulsatilla (Anemone)

Black-eyed Susan Rudbeckia hirta

Golden Banner   Thermopsis divaricarpa

Current berries

Wax Currant  Ribes cereum                    

Woods’ Rose  Rosa woodsii

Serviceberry  Amelanchier alnifolia

Chokecherry Prunus virginiana

For more information about native shrubs

Almost this same list, plant photos, and some garden design ideas are in this CSU Extension booklet:

Friday, March 19, 2021

Just a Few of My Favorite Useful Plants

By Yvette Henson, San Miguel Basin, CSU Extension

My definition for herbs is ‘useful’ plants.  The Merriam Webster definition of an herb is “any plant with leaves, seeds, or flowers used for flavoring, food, medicine or perfume.” The past two gardening seasons, I have returned to herb gardening like I did when I was first learning to garden, and I have been using my herbs in many ways!  I would like to share with you my favorite herbs and how I use them. Since I garden at 8,400 feet, all these herbs should grow well for anyone who gardens at a high elevation site, with cooler temperatures.

Calendula flowers and seeds

I will start with Calendula officinalis. Most people call it by its Genus name, Calendula, but another common name is pot marigold, alluding the fact that it is edible.  It can be used fresh in a salad or cooked with spinach or added to soup.  It can also be dried and ground and used to color rice, etc. 

Calendula is useful in salves and lotions and is scientifically proven to be good for skin. The variety that is reported to contain high amounts of the compounds that are good for the skin, is ‘Resina’ but any Calendula variety will work. I use the salve for any skin irritation—it is my favorite salve because it is so soothing.  I also made a diaper cream for my granddaughter that works well.  Many recipes can be found on the internet.

You can find Calendula in shades of yellow, orange and peach, the most common being orange.  It is a cool-season annual that grows in average soil.  If happy, it will bloom continuously until a killing frost, and will reseed itself.  The seeds can be collected and re-planted. If stored properly (consistently cool, dry, and dark) the seeds remain viable for about nine years.

German Chamomile, Matricaria chamomilla

For the past two years, I have grown German Chamomile, Matricaria chamomilla, from seed.  When danger of frost is past, I transplant the young, hardened-off seedlings into pots or raised beds in my garden.  I love it for its abundant bloom and delicious-smelling flowers.  It is the yellow disk flowers that contain the fragrance and oils.

Use in tea and infuse in oil for salves. Besides making a calming tea for us to drink, a strong, cooled chamomile tea can be applied to seedling trays at the first sign of damping-off disease, and it really works!  My daughter has eczema.  She uses the salve I made her when she starts getting an outbreak and it clears it up!  It is also a calming salve for babies.

Grow chamomile in well-drained, lean soil. Plant hardened-off seedlings into the garden after chance of frost. Continuously remove blooms as they open to promote continuous bloom.  I dry the cut blooms in paper bags or spread out on newspapers in a dark area. 

Dandelion blooms--Taraxacum officinalis

We built our house on ‘virgin’ land in a Ponderosa/Pinon/Juniper forest. I was so dismayed when the dandelions started coming up— I did not want anything non-native growing without my permission.  Apparently, we brought them here, because they were not there before. Although I tried to remove them, each year they multiplied in number, until I finally gave up. 

Now, I pick the young greens in early spring and sauté them in oil with a dash of lemon at the end.  What a yummy, although bitter, green for an early spring ‘tonic’!  I also make salve by infusing the dried blooms in oil.  I like the dandelion salve for lip balm and to massage sore, dry feet and ankles.  My daughters agree that it is helpful—we do not know if it is the massage or the dandelion oil or both, but it eases the pain. 

I am not recommending that you plant them on purpose—I am sure you can find some dandelions, somewhere, preferably in a place where no weed killer was applied.  Last year, my favorite spring mornings were spent in the sun, watching the bumblebees collect pollen from the dandelion flowers while I picked a bag full of blossoms.  So, why not make a few dandelion chains and blow some seeds into the wind--“If you can’t beat ‘em join ‘em!” -- I think I may make dandelion jelly this spring.  

Friday, March 5, 2021

What is the purpose of wasps?

 By Lisa Mason, Arapahoe County Extension

What is the purpose of wasps?

I am asked this question quite often. Why do we have wasps? What is their purpose? Do we need them?

We have a couple of wasp species that can be a nuisance to people. They tend to give wasps a bad reputation. In reality, wasps are a fascinating, diverse group of insects that play a critical role in our ecosystem!

A beneficial sand wasp (Bembix sp.) hunts caterpillars and flies. They can often be seen visiting flowers for nectar in the summer. Photo: Lisa Mason 

Here are some important facts to know:

    • Two species of wasps Colorado are considered a nuisance: The Western yellow jacket (Vespula pensylvanica) and the European paper wasps (Polistes dominula).
    • Besides those two species, wasps are a very diverse group of insects with thousands and thousands of species documented worldwide. How diverse? Current science says that beetles (Coleoptera) are the largest group of organisms on the planet representing about a quarter of all described species. However, some research suggests that parasitoid wasps are actually the largest group of organisms but we haven’t been able to document all the species. Here is a fun NPR article on subject.
    • Many wasps can’t actually sting including parasitoid wasps and other solitary wasps.
    • Most wasp species are solitary insects. Only wasps in the Vespidae family are social and live in colonies. Often, the social wasps are brightly colored to warn predators that they are dangerous. They will defend their nest and sting if needed.
    • Many other insects mimic the bright colors of social wasps to protect them from predators. This phenomenon is known as Batesian mimicry. Common mimics include flies in the Syrphidae family, also known as flower flies or hover flies. You can observe these harmless insects in flowers in the summer time.
    • Wasps provide valuable ecosystems services to humans because they provide pest control in your landscape. Some wasps are predators and others are parasitoids, meaning the wasps will lay eggs in another host insect and consume the host. Our world would be full of pest insects without wasps!
    • You can thank paper wasps for our current paper production industry! In the 1700’s, paper was made from cotton and linen until there was a shortage of those materials. A French naturalist named Antoine Ferchault de Réaumer had observed how paper wasps use wood fibers to make their paper nests, and thought people could do the same thing to create paper. Paper products today are still made out of cellulose fibers from wood (Paulson and Eaton, 2018).
    European paper wasp (Polistes dominula). Photo: Lisa Mason

    A syrphid fly (Spilomia sp.) that mimics stinging wasps but can't sting. Photo: Lisa Mason 

    What about the “murder hornets”?

    The Asian giant hornet (Vespa mandarinia), the world’s largest hornet, has received a lot of press recently because a small number of individuals were found in Washington state. While the insect may look intimidating, much of the news media is sensationalized.

    I encourage you to read a media interview with Dr. Cranshaw, CSU entomologist. He talks about how calling them “murder hornets” is unnecessary. Many wasps are predators and hunt other insects. The Asian giant hornet is no different. 

    Much of the media has focused on how Asian giant hornets preys on honey bees. While they can prey on honey bees if near a hive, Asian giant hornets are generalist predators. They will feed on a variety of insects and will be opportunistic in hunting. They will not specifically target honey bees unless there is a hive nearby. Beekeepers around the country have more important challenges concerning honey bees including the varroa mite.

    Will the Asian Giant Hornet come to Colorado?

    Short answer: No. We don’t have to worry about the Asian Giant Hornet coming to Colorado for the following reasons:

    ·       Asian giant hornets thrive in different climate than Colorado. They need low-elevation areas and higher moisture levels.

    ·       There are many geographic barriers preventing the Asian giant hornet from spreading including the Rocky Mountains.

    ·       They are unlikely to hitchhike like some other invasive species. 

    ·       Efforts to eradicate the hornet is Washington are occurring now.

    What if I find an Asian Giant Hornet in my backyard?

    Colorado has some wasp species that large and may appear to look similar to the Asian giant hornet. These wasps are harmless and common in Colorado landscapes. The two wasps that may look like the hornet include cicada killers and horntails. Both of these wasps cannot sting you. 

    Cicada killers target cicadas when hunting and provide the prey to their young.

    Horntails appear to have a large “stinger.” This “stinger” can’t sting you at all! It is called an ovipositor, which is adapted to drill into the bark of trees. Female horntails lay their eggs underneath the bark of trees. They don’t harm trees and tend to lay eggs in trees that are already stressed out.

    Solitary wasps such as these found in your landscape are not aggressive and should be left alone. 

    If you are looking for the identification of a wasp found in your landscape, contact your local Extension office for assistance.

    Here is a visual of the Asian giant hornet compared to common, harmless wasps including cicada killers and pigeon tremex horntails. Photo: Texas A&M Extension

Stay tuned for more info on wasps!

Look for future blog posts about wasps! I will discuss the differences between social and solitary wasps, and well as some common and beneficial wasps you might see in your backyard.

Wasps can be scary to people for a variety of reasons, but I hope to article can help instill some appreciation for what all wasps contribute to our ecosystems.