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Mite it bee the scutellum?

Last week, after I published the photo of a crab spider eating a honey bee, a reader wrote to say that the honey bee had a large Varroa mite on its thorax.

What he was seeing is not a Varroa mite but a part of the thorax called the scutellum. The honey bee thorax has several distinct parts but the scutellum is found just aft of the scutum. The scutum is the familiar part of the honey bee that helps us determine a bee’s age: older bees wear the hair off the scutum until it becomes a shiny, dark spot. We are also familiar with the scutum as a place to mark the queen.

Here you can see both the scutum (large anterior part of the thorax) and the scutellum (small posterior part of thorax). The two parts are connected by the scutellar grove.
Here you can see both the scutum (large anterior part of the thorax) and the scutellum (small posterior part of thorax). The two parts are connected by the scutellar grove.

The scutellum is adjacent to the scutum and is connected by a suture. The suture looks like a groove and is often called the scutellar grove, the dorsal groove, or the scutoscutellar groove. The scutellum rises higher than the scutum, a characteristic that is easiest to see from the side of the insect. The diagram of the honey bee thorax below shows the location of the scutellum.

Honey bee thorax (Snodgrass, 1956). The part labeled Scl2 is the scutellum.
Honey bee thorax (Snodgrass, 1956). The part labeled Scl2 is the scutellum.

Speaking of mites, however, the scutellar grove is home to a species of mite, Acarapis dorsalis, that is very similar to the tracheal mite, Acarapis woodi. The major difference between these two parasites is the place they call home—one prefers the trachea and the other is partial to the scutellar grove. A. dorsalis is generally not considered a problem for honey bees unless the populations grow excessively large—a situation that occurs only rarely.

Rusty
HoneyBeeSuite

Mason bee covered in mites

I try to remain vigilant for mason bee mites and I use recommended control measures for limiting their impact on the few mason bees I have. But earlier this year I saw my first really bad case of hairy-footed mites on the backs of two newly-emerged mason bees.

The bees in question emerged not from my mason bee houses, but from a little moisture drain on the bottom of a bedroom window. I heard the window buzzing and I was perplexed as to what was going on. After several hours of commotion, two masons emerged into the space between the window and the screen.

The adult female must have crawled into the little drain hole on the outside of the house and, the following spring, the new-born bees emerged through the window frame. I thought the whole thing was adorable until I took a closer look: each of the bees was covered with what looked like sticky brown fluff—in other words, an infestation of hairy-footed mites.

The infestation was so bad that I suspect mason bees have been nesting in those drain holes for more than one season. I tried to photograph them through the glass (which didn’t work so well) but you can see the coating of mites, which looks something like a brown shearling vest. One of the bees was rising up on its hind feet trying to fly, but the weight of the mites was overwhelming.

The hairy-footed mite (Chaetodactylus) is also known as the pollen mite. A special nymph stage, called a hypopus, rides around on the back of an adult bees until it finds a source of pollen to eat. But frequently the adult bee unwittingly takes the mite home. The mites reproduce within the larval chamber where they eat the pollen provisions the bee left for her own offspring. With no food stores, the bee larvae die. Sometimes the mites eat the bee egg or larva as well. If you open a mite-infected tube, you can often find a mass of orange-colored mite debris filling a cell—a sure sign they were busy eating and reproducing for a long while.

In the spring, surviving bees crawl through the nesting cavity where they pick up a great many of the phoretic nymphs that are designed to grip onto the bee and not let go. From there, they are carried to flowers or into new nesting cavities.

The mites are native to North America and can infect many of the bees in the Megachilidae family, which includes the mason bees, leafcutters, and carder bees. They prefer damp environments—one reason they are proliferating in the coastal Pacific Northwest.

Rusty
HoneyBeeSuite

Newly emerged mason bee covered in hairy-footed mites.
Newly emerged mason bee covered in hairy-footed mites.

HopGuard: first impressions

It’s been over a year since I last treated for mites. However, due to a recent increase in deformed wing virus, I decided to treat for mites before winter sets in. I prefer winter bees (those that live many months cooped up in the hive) that have not been directly exposed to any mite treatment. Consequently, I strive to have mite treatments completed by the end of August.

Although the directions say that honey supers do not have to be removed during treatment, I received a note from a reader saying that he could detect the odor of HopGuard in his honey supers. I decided it wasn’t worth the risk, so I pulled the supers before doing the treatment.

As a point of comparison, the only mite treatments I have used in the past have been ApiLife Var (a biscuit-like thymol product), ApiGuard (a gelatinous thymol product), and Mite-Away II (pads soaked with formic acid). Like HopGuard, these products are considered “soft” chemicals, meaning they are naturally-occurring substances that kill mites rather than synthetically manufactured molecules.

I found the previous products to be extremely effective but really unpleasant. The worst part is having to make the hive into a “fumigation chamber” and locking down all the natural ventilation. Also, I hated the smell of those products, so I was ready to give HopGuard a try. So here are my reactions, divided into positive and negative.

Positive:

  • I was pleasantly surprised by the odor. I was expecting the worst after that one reader comment, but I found very little in the way of offensive odor, even when opening the new package. To me it smelled faintly of hops—not strong like when I’m brewing beer—but just slightly hoppy.
  • Quantities were easy to figure for each hive. One strip per five frames of bees seemed a little more tailored than the quantities recommended by the other products. I used anywhere from one to six strips, depending on the colony size.
  • The bees seemed unperturbed when I placed the strips in the hive. My bees usually go ballistic when I apply the other products, but they seemed not to be offended by the odor of HopGuard any more than I was.
  • In the past when I had to lock down the ventilation, mite treatments were followed by much bearding and general unrest. With the HopGuard everything seemed normal after the application.
  • HopGuard lists no temperature restrictions the way the other products do. The thymol products are ineffective when it’s too cold, formic products are dangerous when it’s too hot. HopGuard is just plain easier.
  • The price: this stuff is a whole lot cheaper than other soft treatments. It is actually affordable.

Negative:

  • OMG! HopGuard gives new meaning to the word “messy.” I was ready for this, having watched the video, and even brought rags and extra nitrile gloves with me. Still, after the first three or four hives, HopGuard was everywhere. By the time I was done, I had to wash my hive tools, the smoker, the propane torch (used for lighting the smoker), the bucket I used to carry things, my bee suit, rags . . . even my shoes. Beekeepers are used to things sticky, but even so . . .
  • The directions for use are glued to the outside of the foil package. They became completely saturated and unreadable after a few hives. I would prefer to have the directions separate from the package. Although some general directions are found online along with the video, I haven’t found the actual package insert. It would be a nice thing to have.
  • I don’t like the idea that I need to distribute the strips among the brood boxes. For the most part, I can’t move my brood boxes this time of year. Some weigh 80 or 90 pounds, and I weigh like 115, so moving them just ain’t gonna happen. I ended up carrying an extra brood box with me, removing enough frames from the top box so I could reach down into the lower box and insert the strips. Then I had to replace the frames in the top box and add those strips. Meanwhile HopGuard is smeared over every conceivable surface and it’s about 200 degrees in my bee suit. This problem was even worse in my triple deep hives.
  • Related to the above is the fact that I don’t like to tear my hives apart this time of year. Honey cells inevitably break open and attract robbers and predators. In addition, I run the risk of killing the queen in a season when the drones are gone and the colony can’t replace her. Is it really necessary to put the strips in each brood box or could they all be put in the top box?
  • When I opened the foil package, I knew I would not use the entire package in one day. In light of that, I opened the package as carefully as possible, conserving ever millimeter of the bag length. Still, at the end of the day, there was not enough bag left to wrap and store the contents. The directions say you can store the extra strips in the foil bag, but there’s no way. I folded the foil over as well as I could, then wrapped the foil bag in plastic wrap, and put the whole thing in a plastic bag, and put the bag in a bucket. Next time I went to use it, HopGuard had leaked everywhere. I hope BetaTec is reading this because we need a longer bag!

If the HopGuard works, I would use it again in spite of the inconvenience. I liked the way the bees responded to it, I like the price, I like the smell, and I like the fact it is made from all food-grade products. These are all big advantages. Still, if some of the other issues were addressed I think the product would be a lot easier to use.

Rusty

HoneyBeeSuite.com

What history tells us about hive ventilation

Yesterday I began reading The Quest for the Perfect Hive: A History of Innovation in Bee Culture by entomologist Gene Kritsky (2010). The book is a history of hive design from ancient times to the present, including drawings, photos and descriptions of what worked, what didn’t, and why some hives were more popular than others regardless of how they worked.

I’m only about half way through the book—57% if you believe my Kindle—but one recurring theme kept me awake last night . . . ventilation.

In hive after hive, Kritsky details the various ventilation provisions designed for both temperature control and moisture removal. Pottery hives dating back to 500 BCE had lids with vent holes. Skep hives in the 1800s had lids with adjustable zinc ventilators. Some hives in the late 1800s had multiple ventilators with internal thermometers that could be read by pulling open a sliding door. A similar hive featured a perforated floor where air flow could be adjusted with a metal slide. Hive after hive had features that could help the bees stay comfortable.

The original Langstroth hive was a warren of creature amenities that included double-paned glass sides for insulation and moisture control, a sloping bottom that allowed drainage of rainwater, and a screened ventilation port at the bottom with an adjustable panel. As Langstroth’s hive evolved, feature after feature was discarded. Except for bee space and movable frames, what we now call a Langstroth hive bears very little resemblance to the original.

Although many beekeepers view ventilation as a non-essential luxury, many others believe ventilation is key to long-term honey bee health and high productivity. Too much heat causes bees to congregate on the outside of the hive; too much cold can kill a colony. Too much moisture in the summer makes drying honey energy-expensive and time-consuming; too much moisture in winter can chill the bees and promote disease.

As I said, I’ve not finished reading the book. But I assume our indifference to proper ventilation stems from a desire for easy-to-use and inexpensive hives—hives that will quickly give us a return on investment. Have we chosen high honey production and efficient pollination service over long-term honey bee health?

A vast number of new beekeepers fail after the first or second winter. A lot of those beekeepers plunked down good money for a “complete hive kit” or some variation—most of which have no provision for hive ventilation. (Although, since the advent of Varroa mites, you sometimes get a screened bottom board with a beginner kit.) So the nascent beekeeper—already at a disadvantage because of lack of experience—is further handicapped by a deficient hive. This hardly seems fair.

I think it’s time we review a few thousand years of beekeeping history and embrace what those before us knew: ventilation is vital. We cannot raise healthy, productive bees in a stuffy, damp, over-heated, and pathogen-laden environment. Beyond the economic cost, it borders on cruelty.

Rusty

Wednesday wordphile: survivor stock

Recently, during a discussion with a professor of entomology who is also a beekeeper, I used the term “survivor stock.” He looked at me as if I’d just left my ship hovering above a corn field, slid down the chute, and landed on three feet.

It reminded me of why I write Wednesday Wordphile in the first place: because a word or term that is obvious to one person may be completely foreign to another. Nothing jeopardizes communication faster.

Okay, so survivor stock can be any organism that survives a stressful event and lives to tell about it. The “event” can be anything that a scientist wants to study. With honey bees, the event may be winter. Or it may be a predator, pathogen, parasite, or poison. The survivors of the event are then used to breed more bees in the hope that the genetics that allowed survival will be passed on to the next generation.

Sometimes this works and sometimes it doesn’t. Some other random or unknown cause may have allowed certain individuals to survive, and this external (or exogenous) variable may have nothing to do with the bees’ genetics. But you don’t know that in the beginning, so you experiment. You raise bees from the survivors and see if those bees can survive similar conditions.

Today the term is most often associated with Varroa mites. The survivor stock is comprised of bees that successfully overwintered in the presence of Varroa mites with no chemical treatments. If the offspring of these bees is also able to survive in the presence of mites, breeders will be on their way to producing a Varroa-resistant strain.