Plant Fuzz Plugs & Anthidium

White Plant Fuzz nest plugs made by Anthidium sp.

White Plant Fuzz nest plugs made by Anthidium sp.

What’s white, furry, sits in a bee block, and looks like a joke? An Anthidium nest plug made from Plant Fuzz! Seriously, it looks like someone stuffed a cotton ball into the nesting tunnel(s). Well, someone – or something – did, and she was a wool-carder bee.

These uncommon nest plugs tend to be found in groups, so if your block has one, it is likely to have many. These plugs tend to be in the larger diameter tunnels, since the bees that make these plugs are fairly good sized.

 

Anthidium oblongatum

Anthidium sp. visiting a flower. (Photo by D. Wilson)

The bees superficially resemble yellowjackets in that they are robust black bees with yellow marking and not terribly hairy. The bees are a rounder, shinier and nest in the blocks, which the yellowjackets don’t do (although next year’s queens may spend the winter in your block). Two of our more common species are introduced, but we do have native species that nest in our blocks.

Unlike most our other bees, the males of a given Anthidium species tend to be larger than their female counterparts, and are often reared from the innermost (first constructed) cells in a nest. The males can be territorial over a patch of their favorite flowers and may be seen, rather aggressively, chasing away anyone who dares enters “his” turf.  Fear not, he doesn’t have a stinger (though he does have formidable mandibles and can dispatch smaller insects, including honey bees).

Where do the females get the fuzz for their nests? Not from the end of a Q-tipTM, that’s for sure.  They are very adept at finding hairy plants (sagebrush, lamb’s ear…), scraping the hairs into a ball and carrying them back to their nests. They are, after all, in the family Megachilidae, with the rest of the Leaf-cutting bees. They could be called the leaf-scraper bees, but they are known as with wool carders, since they card the “wool” of plants. They not only make nest plugs from plant fuzz, but they line their cells with it as well. These larvae have it made, lying in a bed of fluff, eating pollen all day long!

A female Anthidium scrapes fuzz of plant leaves as wads it up into a ball in preparation for carrying back to her nest.

A female Anthidium scrapes fuzz of leaves and wads it up into a ball in preparation for carrying it back to her nest.

Balded leaves indicate Anthidium have been here.

Bee pattern baldness on leaves indicates Anthidium have been here.

Advertisements
Posted in 2015, Nest Plugs, Plugs and Bugs | Leave a comment

Colorado’s “newest” bee

A female Megachile apicalis, the first specimen documenting this species now occurs in Colorado.

A female Megachile apicalis, the first specimen that documents this species in Colorado.

Megachile apicalis, a species introduced from Europe and a close relative of the alfalfa leaf-cutting bee, has made its way to Colorado, and what a stunner she is!  We reared this bee from one of The Bees’ Needs 2013 bee blocks that was located in Golden, Colorado.  This individual was just recently identified, adding yet another bee species to our ever growing Colorado list.

It will be interesting to watch over the next few years to see how, or if, it will move across the state.  You can check out its worldwide distribution (minus a Colorado dot that has yet to be added) at http://www.discoverlife.org/mp/20m?kind=Megachile+apicalis .

Slightly recessed whole leaf piece plug with veins and hairs clearly visible.

Slightly recessed whole leaf piece plug with veins and hairs clearly visible. Isn’t it cute?

And in case you were wondering — this species uses several overlapping whole leaf pieces to plug their nests, similar to our ever popular and also introduced, alfalfa leaf-cutting bee.

Posted in 2013, Bee Blocks, Nest Plugs, Uncategorized | Leave a comment

Silk Plugs & Hylaeus

A male Hylaeus shows off his yellow face while sunning on an alyssum leaf.

A male Hylaeus shows off his yellow face while sunning on an alyssum leaf.

One of the less common types of nest plugs we get in our bee blocks are the Silk plugs made by the yellow-faced or masked bees, Hylaeus species.  They are a real treat for those who do see them, often blindingly shiny due to their cellophane-like texture. These filmy plugs are essentially dried bee saliva.  They come in a several colors (white, clear, or yellow) and depths (recessed, flush, or plastered to the outside of the bee block), but are all made by one of our 16 species of Hylaeus that occur here in Colorado.

A shiny Hylaeus nest plug made from Silk, flush with the nest entrance.

A shiny Hylaeus nest plug made from Silk, flush with the nest entrance.

The other plug types that they are most commonly confused with are the resin plugs and spider webs.  The easiest way to separate silk plugs from resin plugs is to poke the plug with the point of your pencil.  If your pencil point tears a hole in the now-obviously filmy plug, you have silk.  If it gets all gummy or if it barely scratches the surface of the super hard plug, you have resin.  As for the spider webs, OK, they’re silk too, but we couldn’t really refer to the Hylaeus plugs as “dried bee-spit” plugs, now could we?  I suppose we could call them “cellophane” plugs, but it seems like cellophane has decreased in popularity despite Lady GaGa using it as clothing.  But back to spiders– their “plugs” are a compilation of threadlike filaments, where as the Hylaeus silk is more sheetlike.  If you do the pencil point poke test to a spider web, you’ll feel a definite spring-like or cushiony bounce.  Hylaeus nests are made in the small tunnels, 1/4 inch in diameter or less.  Some will even nests in tunnels as small as 1/16 inch in diameter. Now that’s a small bee!

A recessed yellow Silk plug made by Hylaeus verticalis.

A recessed yellow Silk plug made by Hylaeus verticalis.

Hylaeus are wildly different from the leaf-cutting and mason bees in the family Megachilidae.  In fact, they are in a whole different bee family – the Colletidae.  Other cool facts about Hylaeus are that they carry pollen in their crop (stomach) rather than on their legs or “bellies”, the larvae do not spin cocoons before pupating, and the adults produce a chemical that makes them smell like lemons if you handle them. (I don’t recommend it though– their potent, yet short-lived stings feel like hot needles.)

Female Hylaeus

Female Hylaeus

Hylaeus adults superficially resemble wasps more than bees.  They are small, black and, since they carry pollen internally, are rather bald.  The yellow face markings on the females are on the inner edges of the eyes (sometimes with an additional central spot about their mandibles).  Of course our largest species lack any yellow markings at all, and one of our most common (introduced) yellow-faced bees actually has white markings, not yellow.  The easiest way to know you had Hylaeus nesting is to identify the plug!  So get out your pencil points and poke ’em.

Hylaeus female working on her nest, note the very liquid pale pollen provisions in the silk lined cells.

Hylaeus female working on her nest, note the very liquid pale pollen provisions in the silk lined cells.

Posted in 2015, Nest Plugs, Plugs and Bugs, Uncategorized | Leave a comment

Grass Plugs & Isodontia

Nest plug of Isodontia elegans made from grass.

Nest plug of Isodontia elegans made from grass.

Like the Little Pig who made his house out of Straw, we have wasps that make their nests out of straw too.  Our Isodontia wasps use only Grass to create their cell partitions and nest plugs.  These inch-long gentle giants use some of our largest tunnels.  While Isodontia don’t start nesting until well into the summer, they can produce two generations per year and will nest until our first frost.

Our black Isodontia mexicana brings in grass for her nest.

Our black Isodontia mexicana brings in grass for her nest.

Our rusty orange Isodontia elegans brings grass to her nest.

Our rusty orange Isodontia elegans brings grass to her nest.

 

If you see an Isodontia  wasp, please let us know if she was black or rusty- orange, as that will tell us what species you have.  The black ones are Isodontia mexicana and the rusty orange ones are Isodontia elegans.  There seem to be some differences in their nesting.  I. mexicana seem to come out a week or two before I. elegans, nest in slightly smaller tunnels, and make severely protruding nest plugs.  It is possible for both species to nest in the same block at the same time!

 

A young Isodontia larva feeds on tree crickets and a katydid.

A young Isodontia larva feeds on tree crickets and a katydid.

Unlike bees that provision their nests with pollen, these wasps collect tree crickets (or sometimes young katydids) as food for their babies to feast upon. If you see your wasp dragging home a pale green blob, you’ll know her young will feed well.

A mature Isodontia larva has finished feeding and starts to spin a cocoon.

A mature Isodontia larva has finished feeding and starts to spin a cocoon.

An Isodontia cocoon where the larva will pupate and develop into an adult.

An Isodontia cocoon where the larva will pupate and develop into an adult.

Posted in 2015, Nest Plugs, Plugs and Bugs, Uncategorized | Leave a comment

Boulder County Open Space and City of Boulder Open Space blocks

The Bees’ Needs was very excited to receive funding from the Boulder County Parks and Open Space (BCPOS) this Spring to document nesting bee and wasp diversity and abundance in six natural habitat types on BCPOS properties. This research will establish important baseline monitoring information for BCPOS and will allow us to compare how open space bee and wasp populations compare to those monitored by our volunteers in developed and landscaped parts of the Northern Front Range. As part of this grant, we have 40 hole bee blocks in the field at Mud Lake, Bald Mountain, Heil Valley Ranch, Rabbit Mountain, Coalton Trailhead, and Flagg Park. These properties range in elevation from roughly 8400 ft. to 5200 ft. and represent different types of forest, grassland, and riparian communities. Our superstar undergraduate research assistant, Brian Lobbes, is spending his summer monitoring these blocks and using his talents in photography to carefully document the nest plugs that appear throughout the season. We are excited to use his photographs to improve our identification guides for our volunteers and to eventually make a unique, on-line guide to the bee and wasp nests of the Northern Front Range. Click on any of the images below to see larger versions of them.

This slideshow requires JavaScript.

In the meantime, he’s been busy checking all the blocks (1920 tunnels) every two weeks for signs of nesting activity. These bee blocks differ slightly from the ones our volunteers use, in that all of these blocks will be brought back to the museum at the end of the summer. We plan to rear out the baby bees, wasps, and their parasites that are developing in these blocks, and we will collect them for our museum. In this way, we will be able to make definitive connections between which bees make which types of nest plugs at what time of year, so that we can continue to grow our capacity to assign species identifications to the nest plugs reported by citizen scientists. These specimens will also provide a permanent snapshot of the diversity of bee and wasp species present on these properties in 2015—a valuable asset for future scientists who may wish to study changes in these communities and BCPOS. In addition to our work on County open space properties, we are also continuing our collaboration with City of Boulder Open Space and Mountain Parks—we have blocks at 40 of their trailheads, which are monitored by their volunteers. This work is giving us a great snapshot of diversity on these properties and our conspicuous bee blocks and their educational signage is helping us spread the word about native bees to a big part of our community.

 

 

 

Posted in 2015, Bee Blocks, Nest Plugs | 2 Comments

Chewed Vegetation Plugs (part 2) & the Megachile who make them

Chewed Vegetation nest plug made by Megachile sp.

Chewed Vegetation nest plug made by Megachile sp.

Earlier this spring we talked about the mason bees, Osmia and Hoplitis, that made plugs from chewed vegetation.  Then, the last Plugs & Bugs post focused on Megachile that use whole leaf or petal pieces.  Now we are combining the two to look at the Megachile that make plugs from Chewed Vegetation.

We have multiple Megachile species in the Front Range that plug with chewed vegetation, but unlike the Megachile that use whole leaf pieces to plug the nests and line their cells, the Megachile we are focusing on this week complete their nest plugs with chewed up leaf pulp and do not line their cells with leaf pieces.  Their bodies are long and thin with white stripes made of hairs.  Chewed vegetation plugs, like minced up leaves, start out as bright green, but as they dry they discolor and often pull away from the edges of the nesting tunnels.

Megachile pugnata female (Photo by D. Wilson)

Megachile pugnata female (Photo by D. Wilson)

Megachile (Sayapis) pugnata is a rather pugnacious species.  They are not aggressive towards people, but they do quarrel a bit with their neighbors.  On an active afternoon, they can sometimes be seen just hanging out in their nests, protecting their turf, rather than foraging.  A bee that doesn’t defend her nesting tunnel may lose it to a larger, more persistent female.  M. pugnata is variable in size, but tends to have a large head with a spine on the lower edge of its cheek.  They typically nest in the column 2 tunnels, though large individuals will nest in the column 1 tunnels.

Cross section of a Megachile pugnata nest

Cross section of a Megachile pugnata nest

In creating their nest plugs (and cell partitions), they start with several irregularly shaped pieces of leaf, but then cover this with chewed up leaves.  They will often add soil particles to the chewed vegetation making it appear darker and more grainy than chewed vegetation alone, but you should still be able to detect some green color and fibrous quality .  M. pugnata often recess their nest plugs a good 1/2 inch or more, making them difficult to see and identify (and photograph)!

Megachile subexilis adds chewed leaves to her nest plug

Megachile subexilis adds chewed leaves to her nest plug

Megachile (Chelostomoides) subexilis is a somewhat smaller, less feisty, bee that nests in the column 2 tunnels.  This species often begin their nest plug not with a leaf piece or two, but rather with a base of resin.  They top off their plugs, flush with the face of the nest block, with bright green chewed vegetation, no dirt included.  This species is multi-generational here in Colorado.  After emergence holes appear in the plug, one of the daughters (or a neighbor’s daughter) will clear out the nest remnants and reuse the tunnel herself. 

Two female Megachile subexilis work on plugging their nests as a Leucospis looks on.

Two female Megachile subexilis work on plugging their nests as a Leucospis affinis looks on.

Posted in 2015, Plugs and Bugs, Uncategorized | Leave a comment

Whole leaf-petal pieces & the Leaf-cutting bees, Megachile

Amelanchier leave with Megachile leaf cuts.  Oblong cuts are used to line cells, Round cuts cap cells or plug nests.

Amelanchier leaf with Megachile cuts. Oblong cuts are used to line cells, Round cuts cap cells or plug nests.

Did you ever see perfect circles cut for your rose leaves or even flowers?  Did you wonder who was responsible?  Did you ever imagine it might just be a bee?  All Whole Leaf Piece plugs are made by Megachile, though not all Megachile make whole leaf piece plugs (some use resin or chewed vegetation).  You could say that Megachile are the ultimate leaf-cutting bee.

 

Whole leaf piece plugs are made from circles of leaf, often several overlapping, but sometimes just one solid piece is visible.  They can be loosely packed or “glued” into place.  The veins and often hairs are visible on the pieces of leaf.  Although they usually start out green, they will fade with time.  A variation of this are the bees that cut, not from leaves, but from petals.  Instant potpourri.

Whole leaf peice plug made from multiple leaf pieces, slightly curled on their edges.

Whole leaf piece plug made from multiple leaf pieces, slightly curled on their edges.

Loosely packed pieces of leaf that are not glued in place.

Loosely packed pieces of leaf that are not glued in place.

 

 

 

 

 

 

 

 

Slightly recessed whole leaf piece plug with veins and hairs clearly visible.

Slightly recessed whole leaf piece plug with veins clearly visible.

As whole leaf piece plugs age, they loose their green color, fading to yellow, brown and even sun-bleaching to light grey.

As whole leaf piece plugs age, they loose their green color, fading to yellow, brown and even sun-bleaching to light grey.

 

 

 

 

 

 

 

 

141013_B2_2014-06-18 cropped

 

We have a number of Megachile that plug with whole leaf or petal pieces around Colorado.  These vary in size from small to large.  You can find them in all hole sizes except the smallest ones. They’re starting to nest now and you’ll get to see them throughout the rest of the summer: some species have more than one generation, so watch your whole leaf piece plugs for holes. When you see holes, please submit those data, because that tells us your bees have successfully reproduced. Then you can watch for the daughters to reuse the nests.  We have had as many as 3 consecutive Megachile nests in a single tunnel:  Moms, daughters, and granddaughters!

 

Megachile rotundata, the alfalfa leaf-cutting bee, is a European species that was accidentally introduced to the United States, but is now managed for pollination in alfalfa seed production fields. They’ve done well enough for themselves that they’re incredibly widespread.  This is a common species in our bee blocks.

Megachile inermis elf0010 small

Megachile inermis, the gentle giant of Colorado’s higher elevations.

We also have many NATIVE species that nest in our bee blocks.  Megachile inermis, one of Colorado’s largest Megachile species, is found at higher elevations.  When not provided with a bee block to nest in, this species will nest in aspen logs and often use decaying wood in their plugs along with whole leaf pieces.

 

 

Megachile entering nest with leaf piece.  Note orange scopa.

Megachile with orange scopal hairs on underside of abdomen entering nest with a leaf piece.  Also, note whole leaf piece plug in the neighboring tunnel.

Another smaller native species is Megachile relativa.  These bees have a beautiful orange scopa, the pollen carrying hairs on the underside of their abdomen.

 

 

Our Megachile that plug with whole leaf pieces also line their cells with leaf pieces, like wallpaper for the nursery.

Cross-section of a Megachile inermis nest with 5 cells and whole leaf piece nest plug.

Cross-section of a Megachile inermis nest containing five leaf-lined cells and whole leaf piece nest plug made from many layers of cut leaves.

AND – if you participated in the project last year (thank you!) you may remember reading about Coelioxys, the leaf-cutting cuckoo bees. These bees sneak into a Megachile nest and use their pointy abdomens to slit the cell’s leaf lining and deposit an egg of their own.  Coelioxys eggs aim to hatch before the rightful nest occupants, so that they can mature faster and eat all the food stores right out from underneath the original occupants.

Posted in 2015, Plugs and Bugs, Uncategorized | Leave a comment