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Who's Who in Your Garden: Wool Carder Bees

by Daniel Rivera MG Class of 2020

The hirsute- foliage in author's yard.
Gardening is undoubtedly one of my life’s most enjoyable activities. Being occupied and entertained with nature’s flora and fauna, the soil, and the natural environment can be so fascinating and rewarding. So, it was no wonder I observed and pondered about this creature flying in my garden.  It was in the heat of the day, but this creature caught my attention quickly. It was fast and furious and definitely interactive and obviously communicating with the others. Was it on a mission and for what purpose? Well after a little observation I had more questions and with a little research, I found some answers.  (I have included links so you can get plenty of comprehensive information).

Was it a friend or foe in my garden? I also needed to know if it was part of the local ecological landscape or a newcomer? A bee or a bee-mimic? Bees love to visit flowers, but not everything visiting flowers or buzzing around the garden is a bee. I knew that many beneficial insects imitate bees to avoid unwanted attention from predators such as birds. 

As you already guessed a cursory glance is not enough; we need to do some observing and some investigation.  Observation can be passive; just like spotting what is around you during your daily garden journeys or observing insect flight behaviors. But active observation may require the acquisition of information and it requires patience, attention to detail, and maybe lots of work. After a bit of preliminary study, I found his creature to be a Wool-Carder bee – sometimes it is referred to as “bossy” or “bully bee”. 

The Wool Carder Bee belongs to the family Megachilidae, which includes Leaf-cutter, Wool Carder, and Mason bees. Megachilidae is a family of mostly solitary bees whose pollen-carrying structure - called a scopa- is on the bottom rear of the abdomen. Whereas other bee families mostly carry pollen exclusively on the hind legs; like non-native-European honey bees or our native-humble bumble bees. 

This interesting bee gets part of its name "carder" from its behavior of scraping off hair from fuzzy leaves and stems of hirsute plants such as lamb's ears ornamental or the common Mullein weed. Both of these are non-native plants. The female Wool-Carder uses her mandibles to scrape and collect the soft downy hairs off hirsute-plants to use in building her nest for her young. She then transports her carded harvest of soft plant fibers to her nest site and uses them to line her brood cells.

Anthidium manicatum - L. Barbs on abdomen, M. posterior middle, R. mating view
Obviously, there is a problem with using common names when communicating the identification of flora and fauna. In every country, people have common names of the flora and fauna species that they encounter; and there are just too many hundreds of thousands of species to have common names. Common names get used differently in various countries and may get applied to different species causing confusion.

Ah…but back to my encounter; because then I wondered which Wool-Carder bee is it? Is it a native? There are so many bee species and I really needed to narrow it down. Because the Carder-bees are fast and furious, I needed to adopt the pace of nature. So out came the camera and daily trips to the front yard at various times.

After a bit of photographic luck and research: I narrowed it down to two possible pollinators. Anthidium maculosum and Anthidium manicatum and are both wool-carder bees.  But one is a native and the other is a non-native bee in our region.  So, who’s-who in your garden can be very important for a variety of reasons.  Think: Help desk, UC extension office or perhaps try a dichotomous book key; computer pictorial image keys, and Apps.

  • “The “European wool-carder bee, Anthidium manicatum arrived in North America near Ithaca, NY in 1963. But now, it can be seen across the country. This Wool-carder bee is a highly successful invader, with invasive populations making it to South America, Asia, and New Zealand”. Anthidium manicatum are black and covered with yellow-grey hairs. Their faces and abdomen are covered in yellow spots”. Anthidium manicatum - Wikipedia
  • “The native species in the United States is Anthidium maculosum. It occurs in the western U.S withinin Texas, Arizona, Utah, Colorado, and California to western Oregon. They are present in hot deserts; the Great Basin and Colorado Plateau; Mediterranean California grassland, chaparral, and woodlands; pine-oak forests.”  Anthidium maculosum - Wikipedia

Anthidium manicatum male pictured left side below: Left -By Bruce Marlin -– Wikipedia Right: Shaun Michael and John Ascher at BugGuide.net
I deduced that it was the European-Wool-Carder bee. (Anthidium manicatum); based on my photos, bee behaviors, and, web searches. But view my included photos and let me know what you think ? … that’s how we learn.

So why is this bee so fast and furious in its behavior and flight patterns?  The male wool-carder bees have an aggressive approach to defending its territory and that is to fly directly at the competitor and knock them off their flower.  That is followed by a high-speed chase if the trespasser does not get the communication. The males don't have a stinger, but they do have barbs on the tip of the bottom rear of their abdomen and this supports their combat method. From this behavior, they get the nickname of Bossy bee or Bully bee. Their antics have definitely brought them some bad press of killing honey bees which I did not witness.  But by defending its floral resources and knowing that the female of the species will be looking for the same resources for nest building; the male is successful in mating.  

Host-associations 

The U.S. native Wool-Carder - Anthidium maculosum - is a generalist that has been observed visiting a variety of species within Agavaceae, Asteraceae, Boraginaceae, Convolvulaceae, Ericaceae, Fabaceae, Iridaceae, Lamiaceae, Malvaceae, Orobanchaceae, Plantaginaceae, Polemoniaceae, Rosaceae, and Verbenaceae (Gonzalez and Griswold 2013).

The non-native Wool-Carder - European Anthidium manicatum - is also a generalist that has been observed visiting a variety of species within Acanthaceae, Amaranthaceae, Asteraceae, Boraginaceae, Crassulaceae, Fabaceae, Lamiaceae, Lythraceae, Malvaceae, Plantaginaceae, and Verbenaceae (Gonzalez and Griswold 2013).

Note: Boraginaceae family — occurs on both of The Plant List

  • This is where you will find: the genus Echium is which is in the family Boraginaceae 
  • Also note Asteraceae, Lamiaceae, Malvaceae and Verbenaceae are also common to both (host-associations lists) of both species of wool-carder-bees.

I high-lighted the family Boraginaceae because this is where I encountered the Wool-carder-Bees on the Echium wildpretii  - the Tower of Jewels which belongs to that Family.

Note: Collectively the insect’s behaviors, flight patterns, and plant host associations and my photos, and computer picture searches; helped me narrow down the possibilities and I still cannot be sure that I am correct. Why?  Because insect or plant ID can require dissection - looking at body parts under a hand lens or microscope; looking at wings- numbers and venation, legs, eyes, body and mouthpart types and segments. Mostly learning a new vocabulary of descriptive terms in order to use an ID key and time spent in a lab with any ID classes taken is a must when getting down to species.  

Final tidbits   - From investigation springs food for thought

The wool carder bees are beneficial pollinators and as solitary bees, they nest in existing cavities. In gardens, these sites may include cracks in walls or building foundations or old left-over exit borer holes in wood pallets, crates, and knotholes or drill holes in wood projects as well as in openings in twigs and branches. Her brood cells are lined with the hair she harvested from hirsute plants. Think of the amazing challenges facing single mom bees trying to feed and protect their progeny in a world of habitat fragmentation and degradation. Even though in this case the Wool-cutter species in question happened to be a non-native bee, it still makes you think. 

We know that native bees have an affinity to native flowers and they depend on them for their conservation and success.  Their success will also depend on their capacity to cope with a changing environment and with other associated competitive organisms.

We know non-native bees often prefer non-native flowers and when these are pollinated, there may be an increased risk of the non-native plants spreading into and disrupting ecosystems. 

Both European wool-carder bee and European Honey Bees are non-native generalist-feeders taking nectar and pollen from a variety of different plants. “The introduction and spread of non-native species aggravate the loss in native species and threatens biodiversity (Gibbs and Sheffield 2009). Currently; Anthidium manicatum seems to be most populous in urban environments which tend to offer more non-native introduced plants than do natural areas (Gibbs and Sheffield 2009)”.

Honey bees are not native to the New World and North America has about 4,000 native species of bees. Honey bees were brought to America via assisted migration in the 17th century by the early European settlers. 

Will Putting Honey Bees on Public Lands Threaten our Native Bee populations?" As suitable sites become scarce, commercial beekeepers are increasingly moving their hives out of state into U.S. public lands. Now scientists warn that the millions of introduced honey bees pose a risk to native species by out-competing them for pollen and nectar and altering fragile plant communities.” It is also clear to see how easy it is to transport pathogens or mites along with the honey bees back and forth across state lines repeatedly. But we also know the Honey bees are very important to many commercial crops, but what might be some solutions?  Local hives staying local? 

Somewhere in my research, honey bees were compared to the Borg in Star-Trek as organisms linked in a hive-mind called the Collective. My observations this year in the garden were that hummingbirds and hordes of honey bees known for their floral consistency were first to arrive and quickly dominate the floral spikes of Echium wildpretii the Tower of Jewels. Then followed a bit later by Bubble bees-honey bees- hummers together then as the flower profusion diminished the wool-Carder bees and other bees became at least more perceptible to me.     

Lots to ponder!!

Want to learn more about bees?

Getting to Know our Native Bees - a blog from the UC Master Gardeners of San Bernardino County.

Twelve Native Bees your Might See at Lake Merritt

Choose the right plants for your garden's bees.

Best practices for protecting bees from pesticides - use UC Integrated Pest Management expertise - http://ipm.ucanr.edu/mitigation/protect_bees.html

Learn to be a steward for honeybees and study to become a California Master Beekeeper