Category Archives: Photography

Photo tour of my insect hotel, 2022 edition

Here are photographs of my insect hotel from Spring 2022. It has three levels and features nesting holes of varying diameters so that I can attract multiple species of bees and wasps. If you’d like to see what shows up this spring and summer, follow me on iNaturalist — I post photographs of everything that arrives, plus post photographs of what is inside the nesting tubes at the end of season. The latter is possible because all holes are lined with paper straws or are stems that can be split open. Having nests that can be dismantled also allows me to minimize the number of unwanted parasites and diseases that might otherwise thrive.

Starting from the top, in the attic space, are 7″ sections cut from a princess tree (Paulownia tomentosa) growing in my yard. The wood blocks have slightly smaller-diameter holes (1/2″) and are lined with 6″ lengths of paper bubble-tea straws. Together, these holes will likely attract grass-carrying wasps (Isodontia spp.), eastern carpenter bees (Xylocopa virginica), and sculptured resin bees (Megachile sculpturalis). And, probably, jumping spiders.

The middle section has more traditional offerings, with paper tubes inside nesting trays (I bought them online) and inside blocks with 6″ holes that I drilled. You can buy super-hard paper liners made for insect hotels, or you can be cheap like me and just use paper drinking straws. I found straws online that are a tad shy of 5/16″. There are dozens of bee and wasp species that will use holes of this size. Note that if you splurge on the trays, you’ll need a way to compress them; I use pipe clamps but luggage straps work, too.

The lower level has cavities that are slightly smaller still, to attract bees and wasps that have smaller body sizes. The blocks have 1/4″ holes fitted with paper drinking straws that are just shy of that. Stems to the left of the blocks are 7″ sections of swamp milkweed (Asclepias incarnata) from my garden (I also like bee balm). These smaller nests seem to attract Georgia mason bees (Osmia georgica) and my favorite wasp, Trypoxylon collinum (the male stays home to guard the nest).

Also on the lower level are square holes routered onto a pine board and covered with Plexiglas. This allows me to spy on the bees and wasps as they construct and provision their nests. It’s early in the season so there’s no real excitement in the photograph, but you can see horned-faced mason bees (Osmia cornifrons) in tunnels #2 and #8. They are both males and are waiting for the females to show up. This panel can be taken apart at the end of the season and cleaned.

Finally, I have an array of stems on both sides of the insect hotel to accommodate species that might prefer to nest vertically. I’m hoping to attract some leafcutting bees (Megachile), but they are said to dislike the commotion at large insect hotels. One can always dream.

Using paper straws to line nests

If you want to make your own insect hotel you’ll need to invest in some long drill bits so that your tunnels can be at least 6″ long. I purchased both a standard set (inches) and a metric set, plus two individual bits that I purchased separately. And you should make yourself a little floor brace so that you can drill without the block rotating wildly. For straws, there are dozens of online places to get paper ones, but I’ve also found them at local grocery stores. And when you get to the stage of inserting the straws into blocks, trim the lengths and then crimp the end (see pic, below) so that the inhabitants don’t extend their nesting materials into the block itself; this makes it easier to use a forceps to pull the straw out. Then during the winter, unroll the straw to reveal contents. Save the pupae you want (in small containers, outside, so they develop normally) and discard parasites such as Houdini flies.

Using stems

For making reeds, I highly recommend using a rotary tool with a cut off blade instead of pruners or saws, both of which leave jagged edges and sometimes cause fractures that can allow parasites to get inside the stem. When you’re ready to sort through the stems, use a knife to split open the stem, then use your thumbnail to continue the break to the end. Contents can be cleaned and sorted just as for those inside straws.

Identifying contents

Part of the fun of having an insect hotel is it provides a nice window to all the organisms you might not even know are in your yard. I’ve managed hotels for over a decade and there is always something new each year, and during a pandemic these surprises keep me going. E.g., I found a parasitic beetle last year. So I highly recommend taking photographs of your hotel guests and uploading them onto iNaturalist (free), a site that can often get your organisms identified by other like-minded folks. And I always recommend buying some books. Here are the titles I own:

  • Wasps: A Guide for Eastern North America (Heath Holm)
  • Bees: An Identification and Native Plant Forage Guide (Heather Holm)
  • Common Native Bees of the Eastern United States (Heather Holm)
  • The Bees in Your Backyard (Joseph S. Wilson & Olivia Messinger Carril)

Houdini fly alert for owners of bee hotels

If you have an insect hotel, you should check your mason bee nests for Houdini flies (Cacoxenus indagator) before the season starts. These non-native flies consume the pollen inside mason bee nests, causing the bee larvae to starve to death. They are very easy to get rid if have nesting tubes that can be taken apart.

Killing them at the larval stage is easy. Just unwrap your nesting tubes during the winter and squish the larvae (below) before they mature into adults. If you’re not into squishing things, submerge them in alcohol or soapy water before discarding.

Houdini fly larvae

I had a half-dozen or so cells infested with the flies, so killing them removed approximately 100 individuals (below) from my local population. That won’t eliminate them from my yard but at least my hotel is not part of the problem.

Houdini fly larvae

Here are photographs of the adult. They look like common fruit flies but are darker and considerably less skittish when you approach them — they are so chill you can often squish them with a finger (do that if you can). You’ll notice them lurking around a bee hotel waiting for female mason bees to leave their nesting tube unguarded, then they’ll slip inside and leave a load of eggs.

If you find Houdini flies at your hotel, please upload a photograph to iNaturalist so we can track their spread.

Below are mason bee cocoons, for comparison. You can clean off the frass and mud, wash them, then store outside in a way that protects them from birds and moisture. For details on all how to do that, see this page. If you store them in an unheated garage in a container, check them at least every day so that you can release them.

Mason bee pupae

Free stickers for Darwin Day

I thought I’d use up some of my postcards to send tree-of-life stickers to some fellow science fans. First seven (7) people to send me their addresses get them. United States only, with apologies (I only have domestic stamps). As a bonus, postcards are sciency! Except for the one from Mohonk Mountain House (pics if you haven’t been there).

Charles Darwin's tree of life sketch (modification)

In case you’re curious, this is a modification of Charles Darwin’s “I think” sketch. I originally used the design for temporary tattoos to help people publicly express their acceptance of evolution.

Tree of life tattoo on neck