Yellow Star Thistle Produces Green Honey


Yellow star thistle (Centaurea solstitialis) was extremely prolific in some areas of California this year.  Many commercial beekeepers commented on it.  One said that he hadn’t seen this much star thistle in over 20 years.  Personally, I saw huge fields of it all over the Sacramento Valley, from Redding down to Davis. Further south, I didn’t see nearly as much as it is considered a noxious weed and invasive species, and the eradication programs may be working well in the southern regions.

Yellow star thistle nectar
Yellow star thistle nectar closeup

Yellow star thistle originates from the Mediterranean. The similar climate of the Central Valley makes it ideal for it to grow.  According to the USDA, yellow star thistle has spread to 15 million acres in the western states.  Yellow star thistle is bad news for grazing animals because it out competes native plants and can also be a physical barrier.  Walking through a patch of star thistle will result in its skinny sharp thorns piercing right through a person’s pants. It is unfortunate that yellow star thistle has some undesirable qualities.  For their part, beekeepers love it because it produces a uniquely colored honey with a complex flavor profile and can sell for a premium.  It can retail for up to $12 in half pint jars.  Wholesale buckets have sold for $3 a pound and barrels for $2.85 a pound.

Star Thistle Nectar

Pure yellow star thistle honey is actually green.  I have never seen it pure enough to be outright green, but I have seen it as a light amber honey with a definite greenish hue to it.  I have seen pure yellow star thistle nectar in the comb and it looks dark green.  That was likely due to the bees back filling the brood nest with it. The comb was dark, which made the nectar appear dark green.  When I poked at it with my hive tool to taste it, it appeared much lighter but still very green.


Dried up yellow star thistle
Dried up yellow star thistle (Warning: do not attempt to walk through this stuff)



Empty Calories

Foragers gathering fresh sawdust. Photo: Mike Connor

Somewhere early on in a “Beekeeping 101” class you’ll learn that honey bees forage for 4 things: nectar, pollen, propolis, and water. The nectar and pollen become honey and bee bread to provide sustenance. Propolis is used as a structural component and also contributes to colony health through immunological activity. Previous blog posts about propolis here and here provide more information. Water is necessary for a variety of purposes including preparation of brood food and evaporative cooling. So in addition to water, bees need 3 substances produced by plants. But do they collect anything else? Of course they do. If you’ve ever seen open syrup feeding, it’s apparent that the bees will forego the flower visitation part of foraging when a sweet liquid is provided. Bees will also readily gather pollen substitute when bulk fed in powder form. While these nectar and pollen surrogates may not be as attractive or nutritious as the genuine articles they are intended to replicate, they can be important in getting colonies through lean times.

Flowers and their surrogates are what the bees should be getting into, but what are they actually getting into? Some beekeepers have a perception that if bees gather it they must need it, but in my time working in and around bees I’ve seen them get into a lot of different things that probably aren’t great for them. One summer we noticed a propolis traps in a yard were yielding a dark brown, almost black propolis with sharp plastic smell instead of the typical red/orange sweet smelling propolis for the area. When we  sat waiting for the construction worker with the Stop/Go sign to allow us through the roadworks where a new topcoat of asphalt was being applied, we noticed bees collecting road tar to use as propolis. This paper detected petroleum derived molecules that matched the chemistry of local asphalt in propolis from urban colonies, confirming that bees will gather sticky stuff other than plant resins. I’ve also seen bees appearing to collect silicon-based caulking product. I’ve often described the physical role of propolis in the colony as bee-glue or caulking, so seeing one bee resort to gathering our version shouldn’t come as a shock if actual resins aren’t available. Bees gather “real” propolis from a variety of botanical sources depending on geography and climate. Some of the most common propolis sources in temperate climates are members of the genus Populus which includes poplars, aspens, and cottonwoods. For more about the role of propolis in the colony and an overview of botanical sources around the world, check out this article.

It’s not just propolis collection where bees make mistakes, sometimes they get it wrong when seeking pollen too. While building woodware in the shop, I’ve seen bees take a lot of interest in the sawdust from both treated and untreated lumber. I’ve never actually seen a forager pack it onto her corbicula, but beekeepers report bees gathering a variety of powdery materials when pollen is scarce. An early study on pollen foraging noted this tendency,  “During periods of pollen scarcity bees are reported to seek substitutes, such as bran, sawdust, and coal dust, which are of no known value for brood rearing.

Just about any sweet liquid is going to get the attention of honey bees, and I’ve seen them investigate many kinds of sodas and juices. This tendency may be a little unnerving to picnickers, but it isn’t really a problem unless there is a more permanent stationary source of sugary liquid that the bees find. One such case happened when some urban bees in NYC found a bit of runoff syrup from a maraschino cherry factory which was only the beginning of the story.


2019 California Spring Update

Many California beekeepers reported that the start of this year was the worst in 20+ years. Several factors contributed to this year’s issues, starting with the numerous fires last year causing nearly 3 months of smoke in the area.

A beekeepers yard in September showing smoke from fires in Northern California 2018.
Petal Fall in 2019 in almonds after heavy rain.

Once the days got longer, queens started laying but the temperatures dropped again and egg laying stopped once more resulting in smaller colonies after almonds. In fact, most colonies were 2-3 weeks or even a month behind, which delayed the start of queen production. Many producers had to source bulk bees from beekeepers further south to begin starters, builders and nucs.

Italian Queen selected for hygienic testing.
Carniolan Queen selected for hygienic testing in 2019.

Once queen producers started generating nucs, the weather conditions were still challenging enough that the windows of opportunities for queens to mate were narrow at best. However, many queen producers found the first round of catching queens resulted in better than expected mating percentages, allowing them to somewhat catch up on orders and start replacing their own queens. Around this time beekeepers were treating with terramycin to combat European foulbrood (EFB). Some beekeepers believe as I do, that fungicides play a roll in colonies being more susceptible to brood diseases especially EFB. I do think that some of the EFB outbreaks we see are due to the way commercial beekeepers and queen producers manipulate colonies to shake bulk bees.

Early EFB symptoms, orange arrows indicate larvae I would select for testing, red arrows indicate old larvae I would not test


If you are seeing this or lots of Deformed Wing Virus (DWV) it will be really hard to nurse colonies back to health. This is what happens if you neglect to treat or manipulate colonies to impact mite levels. Red arrows point to varroa mite in or on open brood.

Currently queen producers are re-queening and treating their colonies before shipping off to summer honey and pollination locations. The late spring has provided more rain than the past 8 years and many beekeepers say that rain in May increases the star thistle crop. We are hopeful this year will be a great star thistle honey crop, helping to restore lost colonies and recover some of the income lost due to the late start on queen production.


PollenCheck✓; Citizen scientists meet a new mobile application

We know that pollen is a key resource for honey bees, a resource they must be able to find in sufficient quantity and quality in their local forage. Yet, we know little about the quality of forage available to honey bees throughout the U.S. The Bee Informed Partnership (BIP) is working to fill this knowledge gap.

The Bee Informed Partnership’s (BIP) central mission is to help beekeepers reduce colony losses by identifying best management practices. BIP does this through surveys and by sponsoring a number of programs to inform beekeepers across the country. In fact, the 12th annual colony loss survey and management practice survey is now open; be sure to participate!

BIP sponsors other programs as well, such as Hive-scale monitoring, Sentinel Apiaries,  and the Tech Transfer Teams. The hive scale monitoring program enables beekeepers and beekeeping clubs to gather and use data from their own hives to follow nectar flows, honey production, swarm alerts, theft alerts and other valuable data from their own colony and others around the nation. Sentinel Apiaries combines the use and benefit of the hive scales with monthly monitoring of real-time disease assessments of Varroa and Nosema loads, and act as early warning systems to alert beekeepers of upticks in disease as well as changes in hive weight. And of course, last but not least, BIP collects copious amounts of data from commercial beekeepers serviced by our expert Technical Transfer Teams throughout the US. Most of the data collected is specific to pest and disease loads with the occasional pesticide and pollen analysis. Up to now, it has been difficult, not to mention costly, to collect reliable, nationwide data on pollen quantity and diversity.

Figure 1. Sub-sample of a spring, summer and fall collection. Can you guess which one is which?


BIP is excited to announce the launch of PollenCheck✓!

PollenCheck✓ was designed to facilitate the collection of vast amounts of pollen data and encourage individual “citizen scientists” to participate in a larger scale nutritional survey program.  An easy way to achieve this participation is to use a mobile application running on smartphones. The app provides guidance as users follow the proposed protocol for gathering nutritional data from their own apiaries. In addition, the app facilitates the entry, collection and aggregation of geocoded nutritional data into a centralized cloud-based database.


Figure 2. The PollenCheck app for iPhone (An Android version is also available)

The application prompts the user to enter colony health measurements, such as queen status, colony size, amount of uncapped brood and mite count for example. The specific pollen information required includes, total volume collected and number of colors in a 100 pellet sub-sample as well as the number of pellets of each color.

Collecting pollen is highly rewarding and a valuable learning experience. The benefits of collecting pollen information far outweigh the time-consuming effort. Collecting and processing pollen will tell you much about your bees’ health, give you a pulse of their surrounding environment, provide an historical and geographical context and help you make predictions on colony productivity. After all, ‘You are what you eat’. Do you know what your bees bring back to the nest to feed the up-coming workforce?

BIP will launch the PollenCheck✓ program this coming season as a stand-alone project or as an additional option to the Sentinel Apiary program. All you need to participate in PollenCheck✓ are 2 colonies in the same location, 2 front porch pollen traps (available from Brushy Mountain with our discount code), a PollenCheck✓ pollen processing kit available from BIP at the low cost of $25 and a smartphone (iPhone or Android device) to download the PollenCheck✓ mobile application available in the app store. To learn more about the PollenCheck✓ program and view the tutorial videos on pollen collection and processing, please visit:  If you would like to join this year, or have questions, please contact us at:



Northern California Summer Update 2017

In northern California, after a wet winter and spring it has been a really dry and hot summer. In the spring I saw a lot more chalkbrood than normal, something that was noted nationwide by our other teams. Below are a few images of some of the worst cases photographed. It has been the hottest summer in the 6 years I have lived in northern California, with many weeks above 100F. I was able to document how dry it has been this summer as I traveled around and sampled honey bee colonies for BIP.

Other than the heat, beekeepers in northern California have been dealing with bears, varroa mites, feeding and supplying water to apiaries. Most beekeepers here have treated for varroa mites or are just finishing. Mite levels have not been really high here this summer but I am sure as fall approaches, there will be colonies with higher mite loads. Some beekeepers are experimenting with Oxalic acid and glycerin on shop towels with hopes to have a soft treatment to use. I have taken a picture below of what one of these towels looks like after several days inside of a colony. This colony propolized more than removed the towel. A lot of colonies remove this towel in small pieces that they chew and tear off from the main towel. This contact with the towel with oxalic acid is supposed to suppress the mites for several days. We will need more sampling to see if these towels are working; however I have heard that the towels are not to be relied on with a high infestation and other treatment options should be considered.

Pollen sources have been drying up here so beekeepers are starting to feed artificial pollen. This assists in keeping colony populations elevated and helps colonies deal with the excess oak dew that is coming in and prevents them from plugging out (becoming honey bound). There are a few plants still lingering around, a cool one I like is pictured below called Croton setigerus or commonly named ‘Turkey mullein’ or ‘Dove weed.’ There are a few more plants blooming now but forage is limited. It will be nice to transition into cooler days as the daylight decreases. I look forward to seeing colonies come back from out of state over the next few months to see how they are doing. In the next few months beekeepers will see if their management strategy throughout the year has been successful at keeping mite and virus levels down before we move into the critical fall period.


Lucky-hit Nectar in Creeping Charlie

Creeping charlie has taken over this backyard

In the twin cities, spring brings complaints- about creeping charlie taking over lawns, strangling garden plants, and being generally relentless. But is the creeping charlie flower a good source of food for bees? In researching creeping charlie, we uncovered a fascinating story about this invasive plant’s strategy to draw insect pollinators. Creeping charlie draws a lot of insect visitors, including bees. Sweat bees, bumble bees, and honey bees are among its most popular insect visitors. Creeping charlie flowers have an interesting strategy for rewarding pollinators. This strategy is called “lucky hit.” They produce nectar with an average volume of 0.3 mL per flower, but the amount of nectar varies greatly, with a range of 0.06-2.4 mL of nectar available per flower. Out of 805 flowers, Southwick found that 8% (64/805 flowers) had a large volume of nectar, and the rest of the flowers provided almost none. The availability of nectar also varies throughout the day. As the morning fades into afternoon, “lucky hits” become less frequent, as creeping charlie flowers do not replenish their nectar throughout the day. Most flowers produce their nectar at night or in the early morning, so it is believed that all the “lucky hits” available in the afternoon are ones that were missed by bees and other nectar collectors earlier in the day. This raised an interesting question- is it energetically efficient for a bee to visit creeping charlie? Southwick found that foraging on creeping charlie likely does provide a net gain of energy. Each lucky hit provides enough calories for 5.9 minutes of foraging, and with the density of flowers produced by creeping charlie plants, bees can probably visit enough flowers per minute to make an energetic profit. The plants are able to produce less nectar over time (even though they sometimes they produce a lot), and so conserve energy. As long as they produce ‘lucky hits’ enough to be an energetically profitable food source, bees will continue to visit. Additionally, the lucky hit strategy may increase pollination success for the flower. Assuming bees cannot tell whether a flower is a lucky hit until they are actively visiting, the bees that visit must be persistent to hit the jackpot. Since they don’t spend a lot of time on flowers without nectar, but still transfer pollen from flower to flower during their search, they may pollinate more flowers per minute than they would if each flower had an average amount of nectar.

Photo by Anne Burgess

While Creeping charlie could be a good nectar source for bees, we are not recommending that you let it take over your lawn. Bees need more than nectar- they also need pollen (the main protein source for bees). Pollen is not readily available from creeping charlie. Bees also need a variety of food sources, and the best lawns have many kinds of flowers, hopefully with a range of bloom times. Creeping charlie is invasive, and can prevent you from growing other types of flowers in your lawn. If you are looking to promote pollinator health in your lawn or garden, we recommend planting a diversity of flowers that produce high quality nectar and pollen consistently over the growing season. James Wolfin, a masters student in the Spivak lab studying bee lawns, has provided tips, below, for excluding creeping charlie when establishing a lawn and eradicating it if it has already established. That being said, if your lawn/garden is already overrun with creeping charlie, and you have not had a chance to eradicate it yet, take pleasure in seeing the bees buzzing around it, and look out for when they spend extra time on one bloom. They are likely hitting the jackpot!

When does creeping charlie grow? (Establishing a lawn without creeping charlie)
Creeping charlie prospers most in shaded areas that have poor ground cover, but can become present throughout the entirety of a lawn, especially in situations where there is an abundance of bare ground, or where turf coverage density is low. Once established, creeping charlie has the ability to suppress the growth of surrounding plants, due to a characteristic called “allelopathy”. This means that it releases chemicals into the ground that suppress the growth of surrounding plants. One study (Rice, 1986) found that flowers growing alongside creeping charlie experienced decreased seed germination and faster rates of root and shoot growth.

The first thing to consider when establishing a home lawn should be species selection. Kentucky bluegrass is typically the preferred grass in the Northern US, due to its high quality and winter hardiness, but it struggles in shady areas, leading to poor turfgrass coverage. The combination of bare ground soil and shade serve as an ideal habitat for creeping charlie to establish and potentially spread. To avoid this situation, it is important that homeowners seed grasses that are well adapted to shady areas. Both tall fescue (Festuca anrundinacea) and fine fescue (Festuca spp.) are cool-climate turfgrass species that do grow well in shady areas. You can mix fescues with Kentucky bluegrass to ensure that you have a strong density of grass, even in the shady areas of your yard.

Eradicating creeping charlie
If creeping charlie has already established in your lawn, there are 2 easy ways to eradicate without using chemicals. You can use a sod-cutter, a machine that typically removes sod for transplant into a new lawn, but can be used to quickly remove strips of weeds, like creeping charlie, from a lawn. Removing strips of creeping charlie will create an area of bare soil within the lawn. This is the ideal habitat for creeping charlie to establish, so it is important to completely eradicate it promptly seed with high quality grass to ensure dense, uniform germination throughout the area.

You can also eradicate creeping charlie through solarization. To solarize, you place a clear, plastic sheet over the soil when it is hot and sunny. The clear plastic sheet captures heat and sunlight, raising soil temperatures to the point where grasses and weeds can no longer survive. Solarization is best fit for sunny, flat sites that are below ½ of an acre in size. In cooler climates the process of solarization takes the better part of a growing season, typically 5-6 months, or up to a full year in some instances. The plastic should be removed in the late fall when soil temperatures are 35-55°F so that new grass can be installed via dormant seeding. These temperatures are ideal because the soil is too cold for germination to occur, but the ground is not yet frozen. This ensures that the target species will be the first to germinate. In the spring, the new turfgrass area should be dense, uniform, and free of weed pressure.



Works cited: 

Dickinson, R. and Royer, F. Weeds of North America, University of Chicago Press, Chicago, IL. 2014

Foord, K. 2016. The value of lawn weeds for pollinators: Not all weeds are created equal. Yard and Garden News, University of Minnesota Extension. Accessed 06/19/17

Hultén, E. 1971. The Circumpolar Plants. II. Dicotyledons. Almquist & Wiksell, Sweden.

Hutchings, M.J., Price, E.A.C. 1999. Glechoma hederacea L. (Nepeta glechoma Benth., N. hederacea (L.) Trev.)
Rice, E.L. 1986. Allelopathic growth stimulation. The Science of Allelopathy (eds A.R. Putnam & C.S. Tang), pp. 34-40. Wiley, Chichester, UK.

Southwick, E. E. “Lucky Hit” nectar rewards and energetics of plant and pollinators.” Comparative Physiology and Ecology 7.2 (1982): 51-55.

Southwick, Edward E., Gerald M. Loper, and Steven E. Sadwick. “Nectar production, composition, energetics and pollinator attractiveness in spring flowers of western New York.” American Journal of Botany (1981): 994-1002.


Carolina Jessamine Part 2: does it harm native bees?

This is my second post on the Carolina jessamine plant. The first post covered the effects of Carolina jessamine pollen on Honey bee colonies. The adult bees can become less active and die, and brood can die as well. But the Carolina jessamine plant is native to the Southeast United States. Honey bees are not. They were brought to the Americas by humans. This means that honey bees have not co-evolved with Carolina jessamine the way that native bees have. Do the chemicals in the plant affect native bees as well?

I did a literature search to look for answers to this question. I was able to find studies looking at the effects of a Carolina jessamine alkaloid, gelsemine, on two different native bees: the bumblebee Bombus impatiens and the solitary Megachilid bee Osmia lignaria.

Image by Sue Boo

One paper showed that gelsemine generally decreased the proportion of flowers probed and time spent per flower for most floral visitors, including the solitary bee Osmia lignaria (Adler & Irwin 2005). This means they probably don’t like gelsemine very much. Does that mean it is bad for them? Not necessarily. Sometimes we don’t like things that are good for us, and sometimes we like things that are bad for us.

Another paper showed that feeding Osmia lignaria large amounts of gelsemine did not affect their offspring performance. This means that when adult bees were fed a lot of the alkaloid gelsemine, their eggs/young still took the same amount of time to develop and weighed the same amount as the eggs/young of bees that were not fed gelsemine (Elliot et al. 2008). Does this mean that gelsemine does not harm Osmia lignaria? Well, not necessarily. But all of those measures are important indicators of fitness. It shows that, immediately after eating the chemical, the bees are able to have seemingly normal, healthy offspring. I find it interesting that these bees avoid food containing the gelsemine alkaloid even though it does not affect their offspring performance.

Image by Christopher Johnson

So what about bumblebees? A study from the Manson lab at the University of Toronto found that feeding bumblebees gelsemine reduced the size of their eggs, but only for the subordinate bumble bees. It did not significantly affect dominant (queen) bees (Manson et al. 2009). Why? It might just be because the subordinates are smaller, so the chemical could affect them more than it would a larger, dominant bee.

In another study from the Manson lab, researchers fed gelsemine-laced nectar to the same species of bumblebee, but these bumblebees had had been infected with a common bumblebee gut parasite, the protozoan Crithidia bombi. They found that the gelsemine actually reduced the intensity of the infection in the bumblebees after 7 days. This difference was not as dramatic (i.e. was not statistically significant) after 10 days, so we don’t know how much this could realistically help infected bumbles living in the wild, but the researchers think that infected bees could potentially seek out Carolina jessamine for medicinal purposes (Manson et al. 2010). Do they? We don’t know.

At this point, you may be wondering, what does this all mean? Does Carolina jessamine harm native bees?

Mostly, we don’t know.

But here is what we do know:

One main chemical found in Carolina jasmine pollen does not seem to affect offspring performance of Osmia lignaria, but it does have some negative effects on Bombus impatiens. (We don’t have information on how it affects other native bees.)

The same chemical seems to reduce the intensity of Crithidia bombi, a common pathogen of bumblebees, in the bumblebee gut. It is possible that eating some of the chemical could help a bee infected with this pathogen survive.

Native bees are less likely to be negatively affected by Carolina jessamine than honey bees, because native bees and Caroline jessamine are both native to the US, and have had time to co-evolve.

Am I suggesting we eradicate Carolina jessamine?

Nope! I just thought these studies were interesting.


Cited Papers

Adler, Lynn S., and Rebecca E. Irwin. “Ecological costs and benefits of defenses in nectar.” Ecology 86.11 (2005): 2968-2978.

Elliott, Susan E., et al. “The nectar alkaloid, gelsemine, does not affect offspring performance of a native solitary bee, Osmia lignaria (Megachilidae).” Ecological Entomology 33.2 (2008): 298-304.

Manson, Jessamyn S., Michael C. Otterstatter, and James D. Thomson. “Consumption of a nectar alkaloid reduces pathogen load in bumble bees.” Oecologia 162.1 (2010): 81-89.

Manson, Jessamyn S., and James D. Thomson. “Post‐ingestive effects of nectar alkaloids depend on dominance status of bumblebees.” Ecological Entomology 34.4 (2009): 421-426.


Alders Valued as Early NorCal Pollen Source

As January comes to a close and much of the country is still buried in snow, signs of spring are beginning to show here in Northern California. After receiving above-average rainfall this winter, the land feels as if it’s ready to burst with life after years of severe drought. Farmers and beekeepers already have high expectations for the year as reservoirs  fill and the land soaks up rainfall. 

Forage for bees in most of California has been been very scarce in recent years and beekeepers have relied on near year-round protein feeding. This is especially crucial in preparation for taking the bees into the almond orchards in February, when large colonies are desired for pollination.

In addition to feeding protein patties, very early pollen sources can really help jumpstart colonies before the almond bloom and queen breeding season. This year in particular I noticed the bees bringing in large amounts of alder tree pollen in the foothills and parts of the Sacramento valley. A few beekeepers have mentioned that in most years red alder is the first major pollen source of the region, including the Pacific Northwest. Having this natural pollen for the bees to mix with the supplemental feed can stimulate consumption of the patties and help early build-up. This probably due to the fact that the bees need to combine protein sources so all essential amino acids are present in sufficient amounts.

Alter trees seem to prefer “wet feet” and can often be found along bodies of water. In January in Northern California they can easily be seen along the banks of creeks and rivers in the foothills, with the bright yellow catkins standing out starkly against the brown leafless trees. Being a wind pollinated tree, the pollen is produced in copious amounts and the grains can even be seen dusting the ground under the tree.

Because alders do not rely on bees for pollination, they have no need to produce nectar to lure them in. However, their value as the first pollen of the year more than makes up for this shortcoming. This spring keep an eye out for this useful and beautiful tree. Happy beekeeping!


Real Time Disease Load Monitoring Pollen Diversity

It’s the end of another honey bee season – and as the little gals are hunkering down, bracing for the cold winds of winter, our lab technicians are getting to work compiling data and publishing reports. Also coming with the end of the season is the close of our second official year of a project called Tier 4, or Real Time Disease Load Monitoring. This project provides colony health information to commercial, sideline and small-scale beekeepers. This year, fifteen of our Tier 4 participants collaborated with us on the Pollen Trap Collection Pilot study. The purpose of the pollen trap project is to give beekeepers an idea of what flowers their bees are visiting at different points in the season and the quantity of pollen being brought back to the colony. The nutritional value of pollen varies depending on pollen type, and there are few if any flowers that can provide honey bees with all the nutrition they need. In general, floral and pollen diversity means greater nutritional diversity and healthier hives.

The Bee Informed Partnership is celebrating the close of the pollen trap pilot project with a pollen sorting and data reorganization party. Twice a month, from May to September, beekeepers placed pollen traps on Tier 4 Real-Time Disease Load Monitoring hives, and sent collected pollen samples to our lab here at the University of Maryland, College Park. We’re sorting the pollen from each sample into subsamples based on color and comparing the weight of each subsample to the total, giving us the relative quantity of each pollen type. After sorting, each subsample of pollen is placed in separate vials for future analysis.

So what do we do with the pollen when samples arrive in the lab?

Beekeepers take samples approximately around the first and 15th of the month, collecting trapped pollen in 50 mL vials and sending them with collected bee disease load monitoring samples. We label and store pollen samples in a freezer until it’s time for processing. Processing simply means separating the pollen based on color, finding the relative weight of each color type, and separating pollen types for possible further analysis.

Our basic procedure:


  1. We first record the beekeeper and trap number, sample date, and process date.
  2. Then we weigh the entire sample, keeping out roughly 3 grams for analysis and returning the remainder to the vial.
  3. Next we separate the pollen by color. This can take anywhere from 30 minutes to over an hour per sample. This depends on the number and diversity of the pollen and the contrast between pollen types. Moisture in the sample can make the colors bleed into each other and make it difficult to tell one color from another. You can imagine that the goop from a rain-soaked pollen sample is quite difficult (and sometimes impossible) to sort.
  4. Next we color code pollen types for each beekeeper and place piles of sorted pollen in centrifugation tubes for future analysis.
Pollen Sorting
A 3g pollen sample from beekeeper sampled May 30, 2014 seen after color sorting. We found 9 distinct colors present: Yellow, Tan, Orange, Burnt Orange, Beige, Green, Brown, and Dark Brown utilizing a paint color palette. Each color represents different species of plant pollen. I like to outline the shape of my piles; they look like little countries or dramatic Picasso drawings.

If we only had a dollar for every cell in our excel spreadsheet generated from the pollen data, I’ll tell you what! So what can we do with all that data? Well, first of all, we can gain insight into the nutritional diversity of the colony’s diet. Nutritional diversity can be estimated from the number and relative abundance of each pollen type. Relative abundance is based on the weight of pellets sorted within the 3g sample of each color. Of each 3g sample the total weight of a single color will fall between the boundaries of what is considered Abundant, Rare, and Very Rare. This information will be provided to each beekeeper in an end-of-year report coming soon. From this information, beekeepers can gain a better understanding of the foraging behavior of their hives and compare their results to other beekeepers and apiaries in the region. Beekeepers can also make inferences about how well their bees prepared for overwintering and then decide whether or not to provide additional nourishment. Additionally, the results from the project may show whether or not there is a correlation between foraging behaviors and honey bee disease, by matching and comparing the data collected from the pollen project to the disease monitoring data. The next step is to identify the species of pollen and conduct pesticide analysis. Since this was a pilot project, these next steps will be implemented in the future.


Spring in California 2014

The most opportune time for honey bee colonies in most areas of the U.S. is during spring build-up. The surplus of pollen and nectar that usually accompanies spring allows a growing colony to create a surplus of pollen and honey. It is also a time of year where the colony is trying to work through its kinks and get the colonies population dynamics under control as far as nurse bee to worker ratio. This ratio is crucial for hive ventilation and keeping moisture and bacteria from infiltrating the hive and causing problems. Some diseases that arise during this opportunistic time period are Chalkbrood, AFB, EFB and PMS. It is important to recognize these problems early as it may save your honey crop and the headache of trying to support the colony through the summer.

Pollen Stores from Yuba City, CA
Pollen Stores from Yuba City, CA
Cherry Blossom's in an orchard near Stockton, CA
Cherry Blossom’s in an orchard near Stockton, CA
Cherry Tree Orchard near Stockton, CA
Cherry Tree Orchard near Stockton, CA

Other problems during this time include overcrowding/swarming or queen supercedure. A good indicator that a colony is going to swarm is the sudden increase in drone cells. This may be in the form of bridge comb or general drone laying production. It is best to treat colonies in early spring for varroa mites before the colony starts to produce excess drone cells. Once you start seeing a lot of drones it’s a good time to keep your eye out for swarm cells. These cells are a great way to split a colony and create more colonies from existing ones. You can also induce swarming by overcrowding the bees and feeding them pollen and thick sugar syrup.

Emergcency Replacement Cells.
Emergcency Replacement Cells.
Supercedure Cells.
Supercedure Cells.
Feral colony nesting in a tree on the South Rim Trail in Upper Bidwell Park in Chico, CA
Feral colony nesting in a tree on the South Rim Trail in Upper Bidwell Park in Chico, CA

These are all common occurrences during the spring, but the main reason I wanted to write this blog was to share some of the things that I have seen in the field and create an opportunity for you to recognize these symptoms early on. I hope that by viewing these images, you will be able to identify possible disease or pest and seek the appropriate actions in controlling them. Below are images from this spring, the good, the bad and the ugly!!

Canabalism of sealed brood.
Canabalism of sealed brood.
Alfalfa field.
Alfalfa field.
Pollen stores from Glenn, CA
Pollen stores from Glenn, CA

Bald Brood

Bald Brood-Note that the wax moth larvae is usually under the cappings that are very light with a majority of the wax chewed down to the cocoon(this is what gives it the white appearance).
Bald Brood-Note that the wax moth larvae is usually under the cappings that are very light with a majority of the wax chewed down to the cocoon(this is what gives it the white appearance).
Bald Brood- Here you can see where I dug the larvae out of the sealed brood.
Bald Brood- Here you can see where I dug the larvae out of the sealed brood.


Varroa Mite on a newly emerged drone.
Varroa Mite on newly emerged drone.

Chalk Brood

Early stage of Chalkbrood.
Early stage of Chalkbrood.
Chalk Brood on a frame in the center of the brood nest.
Chalk Brood on a frame in the center of the brood nest.


A chewed down sick larvae being removed and another contorted larvae displaying a classic EFB symptom.
A chewed down sick larvae being removed and another contorted larvae displaying a classic EFB symptom.
"Stomach Ache Position"- Contorted Larave starved from Melissococcus plutonius (EFB).
“Stomach Ache Position”- Contorted Larave starved from Melissococcus plutonius (EFB).
Multiple EFB symptoms:  Scale, Contorted Larve, Defined Trachea, chewed down sick larvae.
Multiple EFB symptoms: Scale, Contorted Larve, Defined Trachea, chewed down sick larvae.
Multiple EFB symptoms:  Deflated larvae with defined tracheal system, Scale sunken to the bottom of the cell.
Multiple EFB symptoms: Deflated larvae with defined tracheal system, Scale sunken to the bottom of the cell.
Pollen Stores from Hamilton City, CA.
Pollen Stores from Hamilton City, CA.


Unknown Chemical Damage-awaiting pollen analysis.
Unknown Chemical Damage-awaiting pollen analysis.
Unknown Chemical Damage.
Unknown Chemical Damage.

Be Involved. Be Included. Bee Informed.

Donate Now! →