Bees of the Week: Invasive Species!

We’ve got a doozy of a post for you today. In it we list some introduced bee species (the Starlings of the bee world) that we’ve seen around this season or in the past. Invasive species can be problematic. As the world becomes more interconnected, it’s easy for these cavity nesting species to be transported around the world. Ecosystems have always dealt with invasive species, just on a much smaller scale: before, invaders had to be neighbors and arrive mostly on their own steam so there were naturally much fewer of them.

So why are introduced species problematic, and why should we try to keep native species thriving rather than introducing new ones? When a new species arrives, it will inevitably change things (such as the foods it eats and the materials it uses for its shelter), which causes a ripple effect throughout the entire ecosystem. Food and shelter are limited resources, and sometimes invasive species can outcompete the native ones, which effectively kicks them out. This isn’t in and of itself a bad thing—the world as we know it is a result of new species moving in—but as I mentioned earlier, the influx of invaders is massive compared to how it used to be. Now we have ecosystems that have been entirely overtaken by an “alien”, like the lionfish and cane toad.

So to make a long story short, no matter how good of a pollinator a bee might be(e) and no matter how pretty it is, bringing them into a system where they don’t belong is almost always a bad idea. Bee introductions are usually accidental, but sometimes intentional (like the honey bee). If you see bees for sale on the internet or otherwise, don’t be tempted by a more fruitful garden! Count on our native pollinators to do the job.

Now comes the long part. The following cavity nesting bee species are found in our area:

Hylaeus leptocepalus male, photo by Steve Nanz

Hylaeus leptocepalus male, photo by Steve Nanz

Scientific name: Hylaeus leptocephalus
Common name: Slender-faced masked bee
Family:Colletidae
Nest plug type: Silk
Size: 1/4″ (slender)
Nest tunnels used: 1/16″ to 3/16″
Looks like: slender, shiny, small black bees; males have an ivory-white “mask” on their faces; females have ivory-white stripes along the inside of their compound eyes
Originally from: western Europe and Eastern Asia
Arrived in Colorado: before 1915

Hylaeus punctatus, mating pair, photo by Diane Wilson

Hylaeus punctatus, mating pair, photo by Diane Wilson

Scientific name: Hylaeus punctatus
Common name: Punctate (“punctured”) bee
Family: Colletidae
Nest plug type: Silk
Size: 1/4″
Nest tunnels used: 1/8″ to 3/16″
Looks like: small black bees; males have a short pale yellow “mask” on their faces; females have pale yellow stripes along the inside of their compound eyes
Originally from: Western Europe
Arrived in Colorado: around 2008

Anthidium manicatum, male, photo by Tom Murray

Anthidium manicatum, male, photo by Tom Murray

Scientific name: Anthidium manicatum
Common name: European wool-carder bee
Family: Megachilidae
Nest plug type: “wooly” plant fibers
Size: 1/2″ to 3/4″
Nest tunnels used: 7/16″ to 1/2″
Looks like: robust black bee with yellow markings
Originally from: Europe
Arrived in Colorado: after 2000

Anthidium oblongatum, photo by Diane Wilson

Anthidium oblongatum, photo by Diane Wilson

Scientific name: Anthidium oblongatum
Common name: Carder bee
Family: Megachilidae
Nest plug type: “Wolly” plant fibers
Size: roughly 5/16″
Nest tunnels used: 1/4″ to 3/8″
Looks like: similar to Anthidium manicatum, but smaller, with orange legs and distinct black “V” on the abdomen
Originally from: Europe, the Near East
Arrived in Colorado: after 2000

Megachile rotundata, female, photo by Lynette Schimming

Megachile rotundata, female, photo by Lynette Schimming

Scientific name: Megachile rotundata
Common name: Alfalfa leaf-cutting bee
Family: Megachilidae
Nest plug type: 2 to 4 small leaf pieces
Size: 1/4″ to 3/8″
Nest tunnels used: 1/8″ to 1/2″ (they are very opportunistic!)
Looks like: mostly black bee with white hair bands on abdomen
Originally from: Eurasia
Arrived in Colorado: in the 1950s; now used commercially for alfalfa seed production

The following three species are not yet documented from Colorado, but are spreading across North America (keep your eyes peeled):

Megachile sculpturalis, female, photo by Tom Murray

Megachile sculpturalis, female, photo by Tom Murray


Scientific name: Megachile sculpturalis
Common name: Giant resin bee
Family: Megachilidae
Nest plug type: resin, wood, mud, masticated leaf pulp
Size: 1/2″ to 1″ (huge!)
Nest tunnels: 7/16″ to 1/2″ would be expected
Looks like: very large bee with black head and abdomen, golden hairs on thorax
Originally from:  east Asia; now occurs in the Eastern US, west to Kansas and Nebraska

Osmia cornifrons or Osmia taurus, male, photo by Ted Kropiewnicki

Osmia cornifrons or Osmia taurus, male, photo by Ted Kropiewnicki

Scientific name: Osmia cornifrons
Common name: Horn-faced bee
Family: Megachilidae
Nest plug type: mud
Size: 5/16″ to 7/16″
Nest tunnels used: 1/4″ to 3/8″ would be expected
Looks like: dark metallic bee with golden hairs and slight stripes, long antennae
Originally from: Japan; intentionally introduced for orchard pollination

Scientific name: Osmia taurus
Common name: orchard bee/mason bee
Family: Megachilidae
Nest plug type: mud
Size:5/16″ to 3/8″
Nest tunnels used: 1/4″ to 3/8″ would be expected
Looks like: very similar to Osmia cornifrons
Originally from: Asia; probably accidentally introduced with Osmia cornifrons

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This entry was posted in 2014, Insect of the Week, Uncategorized. Bookmark the permalink.

One Response to Bees of the Week: Invasive Species!

  1. Pingback: New bee species discovered on Vlieland island | Dear Kitty. Some blog

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