A Western Road Trip to Find the Bumblebee Wolf, Philanthus bicinctus

As some of you may know, I am in the planning stages of returning to school.  I am hoping to start a graduate program in Biology within the next few years to study molecular ecology, evolution, and population genetics.  I have already met with a potential graduate advisor and he has suggested that I find a species that interests me before I begin classes and research.  After a few weeks of research and exploration, I believe that I have identified such a species.

The Bumblebee Wolf, formally known as Philanthus bicinctus, is a large digging wasp that lives in coarse sandy and gravel soils near the Rocky Mountains.  I find it interesting for a few reasons.  First, it typically nests in large aggregations.  This means that although the species is solitary, the females nest close together.  This will make finding large numbers relatively easy IF one can find the nesting aggregations.  More on this in a bit.  Second, these wasps seem to have a very particular soil preference.  This has the potential for forcing population isolation, which, coupled with other abiotic factors, may manifest itself in differences between nesting aggregate populations.  Third, as their common name suggests, they provision their nests with Bumblebees.  As somebody very interested in Biodiversity, digging wasps can be seen as an invaluable part of a collector’s toolkit.  As anybody who has used wasps for monitoring populations of other arthropods (spiders, caterpillars, beetles), it is obvious that these creatures are much better at finding insects than we are!  Jean-Henri Fabre marveled that Cerceris tuberculata, a Mediterranean digging wasp that provisions its nest with Weevils, was able to find its prey when he himself had not seen a single one in any of his observations!  I have recently become very interesting in Bumblebees and if this wasp can make my life a little easier, I will welcome its assistance.

The most difficult part of this project will be locating the nesting aggregates.  Howard Ensign Evans noted that some sites can persist for up to at least thirty years.  Evans and O’Neill also wrote about four nesting sites that I am hoping are still in existence.  The first is just south of the southern entrance of Yellowstone National Park.  The second is near the southeast coast of Jackson Lake, WY.  The third is near Chimney Rock, CO  and the last is near Great Sand Dunes.  It is likely that these populations are not in the exact location as they were during the studies conducted in the 1960s through the 1980s, but it is very probable that they are close by.  I plan on taking a trip next summer (2018) in an attempt to find these nesting sites.  When I find the nesting sites, I will take a few samples and excavate a few nests and hopefully find something worth studying that has not already been explored by Evans, O’Neill, Armitage, or Gwynne, the researchers who studies these populations before me.

At a minimum, I will get to see some beautiful parts of the country that I have not been fortunate enough to visit.  At best, I find a species of digging wasps that I can continue to study through my graduate training.  Not many people are studying digging wasps anymore and I’m hoping to change this.

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Tachytes harpax

33.60864, -86.38379, Cook Springs, AL. 17Jul17, about 2:30pm.

Not much to report.  I’ve been spending a lot of time learning about bees so I’ve been identifying less.  I was able to key this to Tachytes harpax, another species I’ve never encountered before.  The main diagnostic features for this were:  long row of hair on the bottom of the hindfemur, black near base of mandible, hindtibia red, hindfemur mostly black, patches of reflective setae on anterolateral surface of scutum.

According to Bug Guide, Tachytes are digging wasps which use grasshoppers and katydids to provision their nests.  The sand in my neck of the woods is pretty dense stuff.  It’s more like weathered sandstone that has begun to form soil again.  It’s pretty compact and not easy to dig in.  I am curious whether this wasp is able to construct nests in hard sandy soils or if she prefers the disturbed areas along the roads and logging trails.

 

Pogonomyrmex comanche

USA-TX-Tarrant- Fort Worth Nature Center and Refuge, Mar.-27-2007, Collected By: Ellen Schwaller and Lauren Geffert

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This container ended up in my collection because I stole it.  Not purposely, though.  Tony Burgess had amassed a decent collection of insects from his Riparian and Prairie Diversity courses at TCU and I was using his Hymenoptera to sharpen my identification skills.  I remember taking this, but it was during a transition time for me and this, along with two other containers of Nature Center ants, never made it home to their drawers in the Geology department storage hallway behind the teaching labs.

I remember that Tony loved this ant.  He was very excited about it but I wasn’t sure why at the time.  As I’ve grown as a teacher and as I’ve thought about this ant, I think his affection was due to its presence at the transition areas of prairie and forest, where the oaks start to grow.  As a teacher, he was concerned with teaching us how to spot differences in the environment in order to understand a place and to tell its story.  P. comanche is an indicator species for this transition and was thus a valuable teaching tool.  I’ve taken a similar approach when teaching my children, instructing them how to spot species that only occur on certain topographies or inclines, such as the American Hogpeanut that only grows on partially well drained soil near the middle third of my hillside.  These types of species are instructive and allow us to learn about our surroundings in an intuitive manner.

 

 

Myzinum obscurum

33.60864, -86.38379, Cook Springs, AL.  17Jul17, about 2:30pm.  Sunny, thunderstorm rolling in.  My second trip to this location.  Found on Sumac flowers in bloom.

I will begin this post with a disclaimer.  Like all of my identifications, I accept the possibility that I may be wrong.  I am an amateur and a hobbyist and I do this because I like to do so.  I am more comfortable with certain groups, such as Vespidae and Crabronidae, than I am with others.  I still need a lot of work with bees and ants and I am forcing myself to study them in my spare time.

So, to the specimen at hand.  From what I can tell from reading threads at BugGuide, Myzinium is a particularly difficult species to key.  I was proud of myself when I first thought that this specimen was an M. maculatum, but when I searched for images of females of this species, I knew that I was wrong.  I went back to the key and cross-referenced my work with some pictures and decided that I think I have an M. obscurum.  This fits the geographical range for the species so that is a plus.  If I’m wrong, I wouldn’t be surprised, though.

The next step is to key the males.  They are extremely difficult to key and the best bet is to dissect them and look at their genitalia.  This is best done when the samples haven’t been pinned for weeks and allowed to desiccate.  I just learned this the hard way.  Luckily, I have a few more specimens preserved so I’ll get on that ASAP.

As with many of my other recent catches, this wasp was seen on the flowers of a blooming Sumac (Rhus sp.) in mid-July.  It would be nice to get some specific biological data for this species, but my research attentions have recently been focused on trap-nesting.  If I spot one out in the field, I may take some time to follow in hopes of finding its nest or observing it mating.

 

Quick Thoughts on Trap Nesting

Since finding one of my trap nests plugged, I've been checking the residents daily. The innermost larvae has already devoured its (presumably her) spider provisions, oriented herself towards the nest entrance, and begun constructing her pupal cocoon.

I am not particularly fond of Krombein's method of splitting the traps open from the rear after the trap has been plugged. It is difficult to get them to split evenly. I think cutting the traps in half and then using a drill press might yield the best result and the best trap for observation. It will also minimize damage to and loss of specimens.

Collection Notes – 17Jul17

At around 1:30pm, I returned to the blooming sumacs to search in the hopes of following a Sphecidae back to her nest.  My plans were changed when I arrived and observed increased activity when compared to my previous visit.  Honeybees were still everywhere, but there were also Formicidae, Polistes, Vespula, Eumeninae, Crabronidae, Megachilidae, Halictidae, not to mention some of the most striking Diptera micics I’ve ever seen.  The mimic below even has a ventral abdominal hook, similar to Trypolylon politum (but more apical).  I thought it was a Masarinae at first, to be honest.  It’s a beautiful insect.


The number of male Myzinum were significantly higher today.  The are long slender wasps and the males are easy to distinguish because the have an upturned hook at the apex of their abdomen.  (The image below is from a Myzinum from Pensacola, FL).


I believe their increased numbers can be attributed to what I believe are female Myzinum.  I collected what I originally to be a Crabronidae, but upon closer inspection that is not the case.  I will have an ID soon and if it proves to be true, I’ll have some local data for this species!  Identifying the female will obviously make it easy to attempt tracking them to their nests.

On the way back home, I stuck my head in an old shed to snap this quick picture of a Polistes nest (I think P. annularis based on coloring, nest size, and nest shape).  I was a little frightened to approach the nest.  These are very big paper wasps with a painful sting.  After the nest breaks up in the late fall, I will go back and collect this.


Not much else to say.  I’d like to focus on ants over the next few trips.  They are difficult to identify past genus with my current skill set and microscope.  Practice makes perfect, though.  I know I have a large diversity of ants in my forest and they would be the perfect subjects to observe and sharpen my ID skills upon.

Evolution of Social Wasps

I am a little over 3/4 of the way though Dr. James H. Hunt's The Evolution of Social Wasps.  It will require another reading before I feel comfortable speaking intelligently about the subject, but the questions and answers it has posed have struck a nerve within me.  I am feeling the same sense of wonder I used to experience while spending countless hours watching ant nests as a child and paper wasps as a young adult.  If I ever return to academia and decide to pursue a Ph.D. it will undoubtably be within the field of evolution.