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Bumble bee on piggy-back plant

Piggy-back plant, also known as youth-on-age, is a delicate little woodland plant in the saxifrage family. The species, Tolmiea menziesii, is native to the Pacific Northwest coast where it grows in moist forested areas and along streams. It is often accompanied by red alder at low to middle elevations. At the base of the heart-shaped leaves, buds develop that grow into new leaves. The new little leaf develops right atop the big leaf, giving rise to the common name.

The flowers are brown to purple and grow on a stalk above the leaves. Every year I look forward to these little harbingers of spring but, until this year, I never knew they had bright orange pollen. The flowers are very small, about 6 to 9 mm long, so you can’t see the pollen without magnification. But last week I noticed that all the bumble bees working these plants were loaded with bright orange pellets.

Rusty
HoneyBeeSuite

I’ve never seen a honey bee on these flowers, but the bumbles love them.
I’ve never seen a honey bee on these flowers, but the bumbles love them.
The long skinny parts of the flower are the petals. The sepals make up the flower tube.
The long skinny parts of the flower are the petals. The sepals make up the flower tube.
The pollen baskets are so bright I can see them at a distance.
The pollen baskets are so bright I can see them at a distance.
Tolmiea menziesii showing piggy-back leaf.
Tolmiea menziesii showing piggy-back leaf.

A bully of a bumble

Last August I was watching this little native bee through the lens. She was hanging onto a thistle with her two front legs while she scraped pollen from her body with the middle two. Then the middle legs passed the pollen back to the rear legs which packed the pollen onto her abdominal scopa. Very coordinated.

She was deep in a thistle, tail in the air minding her own business, when a yellow-faced bumble bee alighted on the same flower about two cm away. The other forty or so flowers were empty, but of course the bumble wanted the one already occupied.

Although there was plenty of room for both, the bumble sidled up to the little bee until they were side-by-side, then the bumble lifted one foreleg and kaboom, struck the little bee in the face and gave her a push.

The little bee lost her footing, fell from the flower and flew away. The big, fat bumble—all alone now—foraged on her prize for a few seconds and then left. Having won the battle, she was no longer interested in the reward. Below is the attack sequence.

Rusty
HoneyBeeSuite

The little native bee is gathering pollen and minding her own business.
The little native bee is gathering pollen and minding her own business.
The bumble bee alights alongside the little bee.
The bumble bee alights alongside the little bee.
The bumble moves in for the attack and strikes the little bee in the face.
The bumble moves in for the attack and strikes the little bee in the face.
The bumble gives a mighty shove with one leg and the little bee loses her footing and flies away.
The bumble gives a mighty shove with one leg and the little bee loses her footing and flies away.
The bumble stays only a moment and then flies away, leaving the flower empty.
The bumble stays only a moment and then flies away, leaving the flower empty.

How to attract bumbles to an artificial nest

If you’ve made or purchased a bumble bee box, you are probably wondering where to put it and how to attract tenants. I’ve scanned dozens of documents looking for the secret formula and learned that location is the most important criterion, followed by nesting material. Moisture control runs a close third. Even so, most bumble bee enthusiasts report an average occupancy rate of about 30 percent.

What follows is a summary of all the suggestions I found. I have a bumble house that I purchased several years ago that I use for show-and-tell, but I’ve never actually set it outside. After one more demonstration later this week, I’m finally going to try it. We get lots of bumbles here of various species, so I’m cautiously optimistic.

Location

I’ll start with location since it is important and comprises many variables:

  • According to The Natural History of Bumblebees by Kearns and Thomson, “by far the best site is a south-facing bank.”
  • The box should be placed in full or partial shade. If the interior gets too hot, the larvae will cook. If the box will be in the sun part of the day, morning sun is better than afternoon sun.
  • The box opening should face the morning sun (east or southeast) even if it is not directly in the sun.
  • The box should be sheltered from the wind.
  • The entrance should be at ground level.
  • Other good nesting areas include:
    • Under a hedge
    • At the base of a fence
    • Alongside a garden shed or wood shed

Nesting Materials

Bumble bees do not collect nesting materials so they select nest sites that are already outfitted with the materials they need. In nature, they often select rodent burrows, birdhouses, leaf litter, or debris piles. You have a much better chance of attracting bumble bees if they approve of your choice. Possible nesting materials include:

  • Dry moss
  • Grass clippings
  • Shredded paper
  • Hamster bedding
  • Upholstery cotton or cotton batting (surgical cotton is too fine and may entangle their legs or wings)

By the way, if you have a two-chambered box, the nesting material goes in the inner one.

Moisture

A bumble bee may set up a nest only to move out if the nest becomes damp or water-logged. To control moisture, place the nest box on a concrete block and provide an over-hanging roof. You can also drill several small drainage holes in the floor of the box. Be sure the nest location is away from sprinklers.

Due to moisture problems, some people prefer to mount the boxes 8-12 inches off the ground, attached to a fence post or building. This above-ground entrance will work for some–but not all–species of bumble bee.

Forage

The nest should be placed within a half-mile of early blooming plants, but the closer the better. If you put the box in an area where bumbles are common, you have a better chance of attracting a nesting female.

Predators

Secure the box to avoid predation from small mammals such as opossums, raccoons, mice, weasels, voles, moles, and shrews that enjoy a savory meal of bee brood. Ants can also be a problem around bumble bee nests. Bumble bees like a secluded spot, so choose an area away from pets and human traffic.

Timing

In many parts of North America the early queens will start house-hunting by mid-February, as soon as the earliest flowers begin to bloom, so it’s not too soon to set out your box.

Rusty
HoneyBeeSuite

 

Bumble bee defecation

I came across this on Wikimedia while I was researching something else. The photographer describes it as, “Slowed down footage of a bee squirting a clear liquid from its anus, taken at the Auckland Botanical Gardens. Originally the event happened fast enough, 4 frames at 30 fps, that it was only viewable upon being slowed down. Since my camera scans from top to bottom, and the bee was positioned in the lower portion of the video, I believe this event actually took more like a tenth of a second instead of an approximately an eighth.”

The original by Athen Ananda is available to view on Wikimedia.[CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons].

I hope you find it . . . let’s say . . . entertaining.

Bumble bee defecating.
Bumble bee defecating.

Rusty
HoneyBeeSuite

Mites on a bumble bee

Yesterday I spent some time deleting photo files from my computer. I was just about to trash this one when I saw two odd-looking dots on the back of the bumble bee. When I enlarged it, I decided the dots looked like mites. If I had noticed them at the time, I would have tried for a better shot. Instead, this is what I have:

Two mites on the thorax of a bumble bee. Photo taken June 2012 near Olympia.
Two mites on the thorax of a bumble bee. Photo taken June 2012 near Olympia.

It turns out these mites are not uncommon. They are most likely in the genus Parasitellus and can be seen singly or in large groups on the thorax of bumble bees.

From what I’ve pieced together, these mites live in the nests of bumble bees and disperse by hitching a ride on foraging bees, preferably queens. The phoretic stage seen in the photo is a deutonymph—one of the larval stages—not a mature adult.

The mites spread when robber bees or cuckoo bees enter the nest, when deutonymphs are left on a flower and hitch a ride on a different bee, or when the mites simply switch from one bee to another. Occasionally they are found in the borrows of small animals and even in honey bee hives, where they do not survive.

It is unclear if the mites do any harm to the bumble bee. In fact, some sources suggested the mites may be predatory on other mites and thus be beneficial to bumble bee colony health.

Rusty
HoneyBeeSuite