Tag Archives: fungi

Sorting through guests at my insect hotels

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When the weather is cold and rainy in winter, I entertain myself by bringing the nests from my bee and wasp hotels inside for photo ops and cleaning. With a hot cup of tea (I’m in a cold basement), I carefully open up all the occupied nesting tunnels, then put the cocoons and larvae into vials so I can see who eventually hatches out in the spring. Here’s my set-up before I made a complete mess:

Removing the paper liners (here, straws from a local supermarket) from the nesting blocks is much easier with a pair of forceps. The blocks are necessary because if I just crammed paper straws into my bee hotel, every single nest would be parasitized by wasps that could easily get access to the larvae along the length of every straw.

Below are the cocoons of a mason bee, separated by mud plugs and covered with frass. They are probably Osmia cornifrons (pic of adult) or Osmia taurus (pic of adult), both introduced species that are frequent visitors at my hotels. Unwrapping the straws is usually pretty easy, but sometimes you need to use the forceps to grab onto the edges to complete the job.

I also had two stems filled with Georgia mason bees (Osmia georgica), a native species that has a beautiful blue body (pic of adult). It has smaller, bright orange frass and uses chewed plants to seal partitions. It also smells different.

Below is a visual reminder of why I need to sort through my nests each year: Houdini flies (Cacoxenus indagator). These kleptoparasitic dipterans eat the pollen balls that mason bees feed on, resulting in the death of the bee. So when I find them send them along to fly heaven. The common name is from their ability to bust open the mud plugs (they have inflatable heads for the job). Here’s a pic of an adult.

I also had grass-carrying wasps move into the observation panel, below, that I built a few years ago. There’s one nest near the top, and one at the very bottom, possibly provisioned by the same female. Because this panel slides in and out of the hotel easily, I was able to get a photographs of the adult, an egg, and a larva last year.

Here’s a close-up of the cocoon from the panel. It’s quite large. A photograph of a cleaned-up cocoon from a previous year is on my iNaturalist account if you want a better view. If you have a good eye, you might be able to make out a book louse (Liposcelis sp.) on the left-hand side of the cocoon. Here’s a close-up from a previous season if you’re curious.

One of my bee hotels is packed full of hollow stems, so for these I use a knife to split them open. Here’s a brood of potter wasps inside one of them. I’m not sure what species they are (or even genus) but I’ll know in several months when they hatch and I can get an identification on iNaturalist. And there’s a possibility that one or more of the larvae is harboring an internal parasite, too. Or at least that’s what happened in a previous year, when a beetle appeared (see my post about it). A beetle parasitizing one of my wasps was not on my Bingo card that year. I love surprises like that.

In the smaller stems I get lots of these cocoons, likely Trypoxylon collinum (pic of adult), a charming little wasp that feeds very small spiders to its young.

Although I enjoy looking through the nesting tubes, the main reason I do it is to make sure I’m not just breeding Houdini flies, pollen mites (pic), and pathogens that could easily spill out into bee and wasp populations near my house. I.e., if during my cleanings I felt that I was doing more harm than good to local native species, I’d shutter my hotels and find alternate entertainment.

As you may have noticed during the above, I love wasps. So if you have a bee hotel and get wasps, that’s a bonus, not a problem. And thus I implore everyone to not kill the larvae and the pupae simply because they are not mason bees. They both pollinate plants, plus wasps are fantastic at patrolling your vegetable gardens for pests, which they take back to their nests to feed to their young. If you’re on the fence about wasps, consider treating yourself to book on their biology and identification. I have Heather Holm’s fantastic Wasps: A Guide for Eastern North America. I’ve also heard great things about Eric Eaton’s Wasps: The Astonishing Diversity of a Misunderstood Insect and Seirian Sumner’s Endless Forms: The Secret World of Wasps.

Back yard insect hotel
Observation panel
Front yard insect hotel

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Below are my other posts about insect hotels if you want to learn more. If you have a question, send me an email via my Contact page.

Some insects I found inside dried Turkish figs from Trader Joe’s

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During an online wasp identification course I participated in several weeks ago, there was a fun discussion about whether commercially-produced figs contained fig wasps (Agaonidae, in the Chalcidoidea). Opinions varied, plus some asserted, as do many internet pages, that even if wasps were once inside the figs that ficain (an enzyme) would completely dissolve their bodies. So I purchased a bag of figs and had a look. I found a wasp in the very first fig, in approximately two seconds. And I found much more than that. Photographic details below.

Photograph of a fig being examined under a dissecting microscope

The wasp was small, like most wasps, so here’s a photograph with an arrow pointing out the position. It was wedged in between some of the involucral bracts just inside the ostiole (opening) of the syconium (the “fruit” that is actually an inverted infructescence). I’m not sure whether the wasp was going in or going out.

Photograph of an opened fig with an arrow showing the location of a dead wasp

Here’s a close-up of the wasp, or at least what’s left of it. The shape and positions of the legs seem to be a good match for Blastophaga psenes, the sole pollinator (I think) of Ficus carica. In particular, the middle femorae are much smaller than the front and hind femorae. And the head is wedge-shaped, another attribute of the family.

The species exists in Turkey and in many other places where figs are grown. E.g., it’s in California because it was deliberately introduced there in 1899. This means, of course, that figs grown in California may have wasps in them, too. I’m just the messenger.

Photograph of a dead fig wasp inside a fig

Below is the dorsal side showing (I think) the quadrate scutellum, another family characteristic. The antennae appear to be folded medially into a streamlined position that I assume is useful for navigating the bract maze. I have more pics on iNaturalist.

Photograph showing the dorsal side of a fig wasp

In a different fig, I found two more wasps of a second species. I don’t have a high confidence in my identification but I think they might be Habrobracon hebetor (Braconidae). This species is a regular inside stored figs because it parasitizes caterpillars that eat dried fruit. This wasp, I’m guessing, oviposited into caterpillar-infested figs after they arrived in California (where Trader Joe’s presumably has a warehouse). I don’t know whether the species occurs in Turkey. I have more pics on iNaturalist.

Photograph of tiny dead wasp next to orange frass

Below is a caterpillar in the same fig as the wasp above. Caterpillars were present in several other figs, too, and they were often accompanied by fungal growth. I don’t have an identification guess but if you recognize it please visit my iNaturalist observation.

Photograph of a dead, shriveled caterpillar

I’m not sure whether it’s a different species, but the cocoons below seem to be lepidopterans, too. Here is the iNaturalist link.

Photograph of two caterpillars inside silk cocoons

Here’s the final type of lepidopteran I found, a pupa. Again, I’m not sure what family it might be in. Here’s the iNaturalist listing. The photograph also shows a good quantity of frass, something I found in many of the figs even when I couldn’t locate a caterpillar. The dark color on the left is from fungal growth.

Photograph of a moth pupa next to fig achenes and black frass

The final insect that turned up is a beetle, which I think might be Carpophilus hemipterus, a species native to Asia but now pretty much everywhere. It’s definitely in California. Here’s my iNaturalist observation if you’d like to weigh in on the identification.

Photograph of black and yellow beetle inside a fig

I’d like to point out that insects are extremely common in stored food so the above doesn’t come as a huge surprise to me. And the figs were clearly labelled “organic”, a term that to me greatly boosts the likelihood that there are organisms inside. Unless you have an allergy to chitin or some other insect component (it happens), inadvertent consumption of arthropods isn’t going to harm you.

What did surprise me was how common fungal growth was in this bag of figs. Below is a photograph of what the fungus usually looked like. Not sure what it is (Aspergillus niger?). Some of them were mildly lit up by 356nm UV light, by the way. I think that’s a bad sign.

Photograph of fungal growth next to achenes inside a fig

But a little research turned up what might be the obvious explanation: wasps that manage to crawl into figs via ostiole can be covered with fungal spores in the same way that they are often covered with pollen (that’s the whole point of fig wasps). Indeed, some fig farmers regularly spray anti-fungals onto figs before the females emerge to prevent them from picking up spores and transmitting them to the next fig. Without such treatment (i.e., at organic farms), it’s not rare to find smuts (Aspergillus spp.), endosepsis (Fusarium spp.), and Alternaria rot. Aside from potentially changing the taste of dried figs, I guess there’s a chance you could get a dose of aflatoxins. There’s research on the issue, even articles on the risk from dried Turkish figs.

When fresh figs start to arrive from California I might sacrifice some for a similar investigation. I’d love to find a fig wasp in better condition so I can photograph it. They are bizarre. But per several sources, many (most?) of the figs in California are produced by plants that don’t need fertilization, so finding one might be a challenge. Still, because fig wasps are naturalized in California, I wouldn’t be surprised if they’d still show up inside those varieties. As a demonstration that wasps are alive and well in California, you can order wasp-laden figs online at FigBid.com (e.g., this listing). Note that you don’t order such figs for eating. They are for placing near your crop of figs so that they can get pollinated. Some of the most delicious varieties of figs need such pollination. And some of the varieties that don’t need figs still develop much tastier fruit when they are pollinated by wasps.

Here’s what the California Fig Advisory Board has to say,

“https://californiafigs.com/faq/#:~:text=I%E2%80%99ve%20heard%20that%20there%20are%20wasps%20in%20figs.%20Is%20this%20true%3F

Next on my to-do list is to find the coffee berry borer (Hypothenemus hampei).

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