Mapping The Bees’ Needs

Hey Bees’ Needs Volunteers and blog followers, my name is Collin Schwantes and I am a recent addition to The Bees’ Needs team. I’m writing this post to tell you about the work I’m doing on the project right now. I’ve just gotten started, so I’ll write again later this summer with some more results. But for now, this is a glimpse of what I’m working on.

You might recall that one of the goals of The Bees’ Needs is to examine how landscape attributes in our communities benefit or discourage native bee and wasp diversity. I have been hired this summer to look into these questions using Geographic Information Systems (GIS) technology. Ultimately, knowing how what we do in our backyards impacts bees and wasps will give us the tools we need to conserve them. The first step is to ask: where are our volunteers seeing the most bee and wasp diversity?

Thanks to all of you, we have an incredibly rich data set that we can use to tackle that question. From my perspective, each of your blocks represents a point on the map where we know something about the bees and wasps living there. Even knowing that no bees or wasps are nesting at your block is important. What we can do next is nearly endless.

I’ve started looking at not only where we find the greatest diversity of nesting bees and wasps, but also at how those “hot spots” for diversity change across the nesting season. For this blog post, I’m going to focus on the greater Boulder area. We know that some bees and wasps build nests early in the year and others later. Using data from each month we can see when and where species start to show up around Boulder. By  interpolating between blocks, we can roughly estimate where bees and wasps are found for the entire area surrounding Boulder, even if we don’t have bee blocks there.

Let’s look at this changing map, below.  It shows us nesting bee and wasp diversity from June to September in 2013. The red areas are those of greatest diversity, and the blue areas are least diverse. You can see that diversity bounces around quite a bit as different wasps and bees start nesting at different times. June and July appear to be the months with the most diversity across all the bee blocks. In August there appears to be some lingering pockets of high diversity.  As I work through subsequent years of  your data from the project, it will be interesting to see if these hot spots stay the same, or change.

Richness

The heat map you see above has error associated with it simply because we can’t sample all the bees and wasps everywhere. As a result, the estimates of diversity made in the heat map may not perfectly reflect what you have recorded in your block. Fortunately, we can use elements of the urban landscape to try to improve those estimates. If our estimates of where bees can be found are closer to what you report, then we have found a piece of the landscape that predicts bee and wasp presence. We can use maps of streets, parking lots and buildings to figure out where bees probably aren’t. Because the bees and wasps we are interested in can’t eat or nest in blacktop, we can be pretty sure that bees and wasps won’t be found in the middle of a King Soopers parking lot. When we include all of those surfaces in our estimation we can cut out a large chunk of the map.

We will probably find that elements of the urban landscape influence bee and wasp species in complex ways. With some things, like tree cover or conservation areas, increasing the number of species we find in a block and other things, like percent impervious surfaces, decreasing diversity. Some species may do really well in the urban core, while others are only able to exist in small pockets of the city. With the knowledge gained from this work, we will know which parts of the city could use a boost in bee and wasp habitat, and which areas we should be protecting.

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Loose Debris Plugs & their Bugs

Loose Debris plug made by Anthidium manicatum in Windsor

Loose Debris plug made by Anthidium manicatum in Windsor

Sticks, and stones, and broken bones, that’s what my nest plug is made of…

The plug type that we are focusing on for this week’s “Plugs & Bugs” is Loose Debris.  In all of our other P&B posts we have talked about plugs that are very sturdy in their construction – plugs fit for fortresses.  This week’s plug seems less secure.  Loose Debris is easily moved or re-moved.  Still, it seems to work in many cases, at least as long as necessary for the young inside to mature.

What is Loose Debris? It’s little bits of organic and inorganic matter that the wasps or bees collect one piece at a time.  It’s not just stick and stones, but seeds, withered anthers, mud clods, bark bits, and even the occasional broken piece of a dead insects.

We have two very different kinds of insects that make loose debris plugs – a wasp (Solierella) and a bee (Anthidium).  Both these genera can have multiple generations per summer here in Colorado.  It is very difficult to tell if a loos debris nest plug has emerged (or has a “hole” in it).  If a lot of the material disappears, record it as having a hole in the plug.

Solierella sp. reared from a nest in Longmont

Solierella sp. reared from a nest in Longmont

Solierella sp. are small, slightly stocky, charcoal grey to black wasps.  There are about a dozen species in Colorado and at least two different species that nest in our blocks.  One of these species nests in the smaller diameter tunnels and provisions their nests with hatchling grasshoppers.  Another species nests in the medium size tunnels and provisions with true bugs (order Hemiptera).  They use loose debris not only for nest plugs, but also for walls that separate the reproductive cells.

Bark bits in Solierella loose debris nest plugs

Bark bits in a Solierella loose debris nest plug

Spent flower parts in Solierella loose debris nest plugs

Spent flower parts in a Solierella loose debris nest plug

 

 

 

 

 

 

 

A female Solierella works on her nest plug

A female Solierella works on her nest plug

A seed and organic parts in a Solierella loose debris nest plug

A seed and organic material in a Solierella loose debris nest plug

 

 

 

 

 

 

 

A female Anthidium foraging

A female Anthidium foraging

Anthidium sp. are the wool-carder bees.  These are the species that line their cells, and often plug their nests with white, cottony, plant fuzz.  Thanks to our volunteers, we’ve learned that some Anthidium plug their nests with sticks and stones after they have completed their pillowy cells.  (Other Anthidium plug with just plant fuzz.)  These nests are built in the tunnels with the largest diameters.  Sometimes the males spend the night in the bee blocks.  Zzzzz Zzzzz.  During the day, the territorial males can be seen “patrolling” flower patches.

Anthidium manicatum nest plug in 1/2" diameter tunnel

Anthidium manicatum loose debris nest plug in a 1/2″ diameter tunnel

 

A different Anthidium nest plug made exclusively of plant fuzz, not capped off with loose debris

A different Anthidium nest plug made exclusively of plant fuzz, not capped off with loose debris

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Chewed Vegetation (part 1) & Mason Bees

A variety of Chewed Vegetation plugs made by Osmia ribifloris

A variety of Chewed Vegetation plugs made by Osmia ribifloris

Depending on species, Leaf-cutting bees (Family Megachilidae) use a variety of things to make nest plugs including mud, resin, plant fuzz, and as their name implies, leaves. Many of our leaf-cutting bees chew leaves into a pulp as they build their nest plugs. Because they are made from chewed vegetation they can have a fibrous characteristic. If you inspect them closely, they are made of bits, like a puree of spinach that hasn’t been strained. They often use leaf pulp alone, with no other ingredients, but some species may incorporate other materials (wood, dirt and even pebbles).

 

Fresh plug made by Hoplitis fulgida

Fresh plug made by Hoplitis fulgida. Note: the bright green chewed leaves used as mortar to hold pebbles in place.

Same nest plug two months later.  Note: green color is totally faded and a few pebbles are missing.

Same nest plug two months later. Note: green color is totally faded and a few pebbles are missing.

 

 

 

 

 

 

 

Newly made chewed vegetation plugs will be green: light green, bright green, or dark green, but green. Just as leaves on trees lose their green and turn colors in the autumn, the chewed vegetation plugs will become less green over time. Once they dry they may look darker, appearing brown or blackish, or they may fade to a sickly olive-tan. Chewed vegetation plugs also have a habit of shrinking and splitting away from the tunnel walls over time. This is the norm for this sort of plug. The fibrous characteristics of these plugs may become exaggerated as the plugs dry. One of the reasons we ask you to check your blocks every two weeks is because these plugs morph over time. It’s easier to see “green” before it fades.

A fresh green chewed vegetation plug completely fills the nest tunnel

A fresh green chewed vegetation plug essentially fills the nest tunnel.

The same plug, later in the season has faded and begun to pull away from the tunnel walls.

The same plug, later in the season has faded and begun to pull away from the tunnel walls.

 

 

 

 

 

 

 

This week we will focus on two of the earlier nesting leaf-cutting bees that use chewed vegetation, the mason bees: Osmia and Hoplitis. Later in the summer we will revisit chewed vegetation plugs and the bee-sties that create those later in the summer.

Osmia spp. – Mason Bees

An Osmia is burried deep in dandelion pollen as she collects food for her offspring.

An Osmia is burried deep in dandelion pollen as she collects food for her offspring. (D. Wilson photo)

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A brilliantly metallic Osmia ribifloris returns to her nest.

 

 

 

 

 

 

 

 

 

Osmia are our earliest spring bees.  These squat bees overwinter as adults (still in their cocoons) and are ready to pop as soon as the spring warms.   While most our Osmia are metallic blue, we do have a few metallic green and black species.  We find the Osmia to be locally common.  When you have them, you may have a lot of them.  They only have one generation per year, so you won’t see any emergence from these nests until next spring.  There are many species that nest in the Front Range.  Most will use the medium sized holes, although some will nest in small or large holes, especially if the medium holes fill up.  These typically use only chewed leaves, although at least one species will add wood chips from the nest block itself in the nest plug.  Perhaps this makes it more camouflaged?  Depending on species, some plugs are flush with the entrance, but many are recessed 1/4 to even 1 inch deep.  These bees visit early spring flowers, and a few specialize on Asteraceae.

 

Hoplitis spp. – Mason Bees

Our jet-black Hoplitis albifrons sips nectar (D. Wilson photo)

Our jet-black Hoplitis albifrons sips nectar (D. Wilson photo)

Our metallic green Hoplitis fulgida visits a flower

Our metallic green Hoplitis fulgida visits a flower (D. Wilson photo)

 

 

 

 

 

 

 

 

Hoplitis are typically the next leaf-cutting bee to appear on the scene, beginning to nest in late spring or early summer.  Closely related to Osmia, Hoplitis are longer and thinner. They vary greatly in color; we have both metallic green and black species that nest here.  They tend to be more common in the foothills.  They nest mostly in the medium size holes, but like other bees, may use the small or larger tunnels if the medium holes are full.  The plugs are totally cool in that they cement little pebbles in place using chewed leaves, creating cobblestone plugs.  These are typically flush or very near the block entrance.

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Resin Plugs (part 1) and their Bugs

Some of the best nest plugs in the bug business are made of sticky plant sap–as it dries, it hardens into a protective door and can stand on its own or be topped off with debris.  Today we’ll cover two insects that nest early in the year and use resin to do it.

A female Aphid Wasp,  Passlaoecus sp.

A female Aphid Wasp, Passlaoecus sp.

The first are wasps from the genus Passaloecus, also called Aphid Wasps because they collect aphids to feed to their offspring.  These wasps are shiny black with pale markings on their mandibles, the basal segments of their antennae and on their front legs.  Boulder County hosts several species that range in size from just over 1/4 inch to 3/4 inch in length.  Watch your boxes carefully and see if you can see them bringing home the bacon (er…aphids) for their babies.

 

Construction starts as a ring of resin all around the entrance but without a middle section so the mother can get in and out. Once her nest is completely provisioned, she’ll fill in the center and seal it off.  Their nest plugs start off tacky then typically dry to a clear or white color. Often they’ll add debris as a finishing touch, but not always. Frequently Passaloecus wasps will nest in small tunnels, but depending on the specific species and number of nests in the block, they can choose medium sized or even large tunnels too.

Passaloecus will often begin their nesting by placing a ring of resin at the tunnel entrance

Passaloecus will often begin their nesting by placing a ring of resin at the tunnel entrance

An Aphid Wasp peers out of her nest

An Aphid Wasp peers out of her nest

 

 

 

 

 

 

 

Passaloecus takes flight to go collect aphids

Passaloecus takes flight to go collect aphids

A female Passaloecus brings in a piece of sawdust to add to her resin nest plug

A female Passaloecus brings in a piece of sawdust to add to her resin nest plug

 

 

 

 

 

 

 

A nest block containing multiple nests of Aphid Wasps

A nest block containing multiple nests of Aphid Wasps

 

If your block has Aphid Wasps, you’ll get very familiar with them–blocks that have any often have many.  It’s unusual to find only 1 or 2 nests and much more common to find 5, 10 or even 15 nests.

 

 

 

 

 

 

A female Heriades

A female Heriades

The second “bug” for our Resin Plugs are small bees, about 3/8 inch long, in the genus Heriades.  These are members of the leaf-cutting bee family, and their bodies are elongate, heavily textured, with white hair bands on abdomen.

You’ll be able to tell Heriades plugs from Passaloecus plugs because the bees’ handiwork tends to be created from a darker resin placed flush with the face of the bee block. Their plugs also have a shiny or glassy texture, not a tacky one, and may be topped with one to three pieces of pebble or wood chips. As the summer progresses and the sun gets hot, any plugs facing south may melt and become gummy, loosing their luster, and sloughing off any debris in the process. Starting in the early summer, you’ll see these nests appearing in smaller hole sizes, particularly in the 1/8″ holes. While Passaloecus wasps tend to congregate, Heriades bees don’t group as much, so you’ll rarely see more than 2 or 3 nests made by these bees in the same block.

Heriades female next to her nest plug

Heriades female next to her nest plug

Heriades nest plug of dark colored resin

Heriades nest plug of dark colored resin

We will revisit Resin Plugs again as we get closer to fall, but until then, keep your eyes peeled for these interesting bees and wasps, and enjoy both the beauty of the insects themselves and the nests they make.

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Spider Web “Plugs” and Spider “Bugs”

Jumping Spider with web in neighboring tunnel

Jumping Spider with web in neighboring tunnel

Spiders strike fear in many of us, but they are an important part of our natural world and can even be pretty darn cute! Your bee block is the perfect place to call home for a variety of critters, so you may find some spiders or their webs. When you find a Spider Web in your block, please report it.  In most cases, we ask that you just let the spider reside in your block.  They may even help keep the parasite populations down.

Most of the spiders you will find in your block will be the cute Jumping spiders.  If you don’t believe Jumping spiders can be cute, this video might just change your mind:

Some spiders may need to be relocated if their webs cover the front of the bee block

Some spiders may need to be relocated if their webs cover the front of the bee block

In a few cases, when other spiders such as Funnel Weavers move in, their webs may cover the entire block.  In this case, we suggest you help your spider move to a new location in your yard–otherwise bees and other pollinators will have trouble getting into, or out of, their nests.

Spider Webs occur in all tunnel sizes and can be found from early spring though late fall.  Since spider webs are variable in appearance, we are including photos here for you to browse through.  Spider webs are made of long strands of threadlike spider silk.  They are typically white, but the stickier ones will have bits of sawdust in them, and if you poke them they’ll feel bouncy or springy.

It can be easy to confuse spider webs with a few different types of plugs, so don’t be afraid to get a closer look.  You’ll soon see the differences. Superficially, spider webs might look like Silk plugs (but silk plugs have a papery texture and tear easily, only occur in small tunnel diameters and only during summer and fall); Loose Debris (which has nothing holding the bits together, unlike a sticky spiderweb); Resin with Debris (which are soldered in place with dried resin); or Plant Fuzz (which is a more solid wad of short fibers).  When in doubt, snap a photo and submit it with your report or post it on the forum!!

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Mud Plugs (part 1) and their Bugs

Mud is used to plug the nests of many wasps and some bee species, including our earliest nesting bee, Osmia lignaria. Mud plugs are a complex set of plugs, with subtle differences that we are starting to understand. For this post, we focus on early season mud plugs. We will revisit mud plugs later in the season as additional wasps that also use mud begin nesting.

When reporting on mud plugs it is most helpful to us if you can include photos of the plugs and any insects you see entering, exiting, or plugging these nests. Adding comments about mud plugs such as the color (dark grey, tan, white, pale grey, reddish), texture (chunky, bumpy, smooth, grainy), and concavity (very concave, flat, bulbous) are most helpful, particularly if an insect was seen entering the nest. These, in combination with the date of observation, distance recessed or protruding, and intactness give us a more complete picture of what is happening. If you see the insect, but can’t photograph it, comments including the color and shape (round blue bee, skinny black wasp, black and yellow striped insect carrying green thing under its body) are very helpful as well.

Some insects that make early season mud plugs include:

Osmia lignaria suns on a leaf

Osmia lignaria suns on a leaf

Osmia lignaria – Blue Orchard Mason Bee
Family: Megachilidae
Bee characteristics: Metallic blue or blue-green, 1/2 inch long, rotund, resembling a fly
Abundance: Locally common across Colorado, especially near early spring blooming deciduous trees
Seasonality: EARLY spring
Nest diameters: Medium (Large if the medium holes fill up)
Plug composition: Mud that is Chunky in texture and usually medium grey in color
Plug depth: usually Flush with nest entrance, sometimes protruding a smidge
Pollen: Many spring blooming species including willows and apples
Generations per year: 1 (no emergence later in the summer)
References: Many books have been written on this one species including:
Pollination with Mason Bees: A Gardener’s Guide to Managing Mason Bees for Fruit Production by Margriet Dogterom and Mason Bees for the Backyard Gardener by Sherian A. Wright
Notes: Two introduced species, Osmia cornifrons and Osmia taurus also plug with mud. These species have NOT been confirmed for Colorado, although a blurry picture exists of a potential individual from Boulder County seen during spring of 2014. If your early season mud plugger is an O. lignaria sized bee with a brassy metallic orange (copper) color, faint striping on the abdomen, and potentially “tusks” on its face, please get a photo if possible and alert Virginia to this observation immediately (Virginia.Scott@Colorado.Edu).

Osmia lignaria haven

Osmia lignaria haven

Chunky Mud plug by Osmia lignaria

Chunky Mud plug by Osmia lignaria

 

 

 

 

 

 

 

 

Stenodynerus sp. working on nest with plug in tunnel below

Stenodynerus sp. working on nest with another plug in tunnel below

 

Stenodynerus sp.
Family (Subfamily): Vespidae (Eumeninae)
Wasp characteristics: Narrow-tapering, black with yellow stripes, similar to a small paperwasp
Abundance: Somewhat uncommon
Seasonality: Late spring
Nest diameters: Small
Plug composition: Mud that is Smooth (sometimes ridged around the edges) and Concave in the center
Plug depth: slightly recessed (~1/8 inch) from nest entrance
Prey: Caterpillars
Generations per year: multiple with spring nests emerging later in the summer, no renesting?
Notes: At least a dozen species of Stenodynerus occur in Colorado although some of these may nest in the ground

Mud plug made by Stenodynerus sp.

Mud plug made by Stenodynerus sp.

Stenodynerus sp.

Stenodynerus sp.

 

 

 

 

 

 

A male specimen of Chelostoma philadelphi

A male specimen of Chelostoma philadelphi

Chelostoma philadelphi
Family: Megachilidae
Bee characteristics: Small, Elongate 5/16” long, Black
Abundance: We have yet to document this bee in our bee blocks, but the bee occurs in Boulder and nests in wood
Seasonality: During Mock-orange bloom (Philadelphus sp.)
Nest diameters: Small
Plug composition: Mud
Plug depth: Flush
Pollen: Visits only Mock-orange for pollen
Generations per year: 1 (no emergence later in the summer)
References: Krombein’s 1967 Trap-nesting Wasps and Bees
Notes: Boulder is the farthest west this species is known to occur, first documented on the CU Campus in 2002 and again in north Boulder in 2014.

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Spring 2015 has Sprung

A male Osmia lignaria flies in Lyons March 28, 2015

A male Osmia lignaria flies in Lyons March 28, 2015

Welcome to 2015!

The Osmia lignaria are flying early this year. If you already have your bee block, make sure it goes up soon, since female O. lignaria are now looking for places to nest. If you’ve registered for a block but haven’t gotten your invite to pick it up – it should be coming in the very near future. Check you email, spam folder, promotions tab… so you don’t miss it.

If you have a 2014 block or even a 2013 block, enjoy watching the offspring emerge and nest, but we will not be having you report on those blocks. We will only be collecting data on 2015 blocks this summer.

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