How to recognize Apoidea

One last post on wasps, while I’m still on the topic.

Bees and spheciform wasps, forming the superfamily Apoidea, are hugely diverse in form, size, color, and habits. The rich variety within Apoidea can make the group difficult to recognize, but most share one particular morphological trait that, with practice, can reliably be used to diagnose these insects from other types of wasps.

(Adapted from Scott & Stojanovich “Stinging Hymenoptera, Pictoral Key To Some Common United States Families”, via the CDC)

The pronotum is the first big dorsal plate on an insect’s thorax, and in apoids this plate ends at the sides in a distinctly rounded lobe that does not touch the tegula, a small plate associated with the wing base. Bees, crabronids, sphecids, ampulicids, and other spheciforms have this distinctive pronotal lobe; similarly sized and colored wasps in the Vespoidea do not.

Hylaeus, a bee, has the rounded pronotal lobe.
Can you spot the lobe in this cicada killer wasp?

In contrast, here is Euodynerus, a vespoid wasp showing the non-apoid pronotum without the distinctive lobe:

In vespoid wasps, the pronotum typically touches the tegula in a sharp angle.


Genomic data reveal that ants and bees are close relatives

Current Biology has just published what is surely among the most significant papers this year on insect evolutionary relationships:

Cladogram depicting relationships among major groups of aculeate wasps, based on analyses of 308 aligned nuclear genes. Branch color represents parasitism (=green) or predation/nest-building (=yellow). Adapted from Figure 3 of Johnson et al (2013).

The importance of the paper derives from a combination of hitting a controversial topic with a much-needed phylogeny, and doing so with a staggering amount of information. The 300 or so genes employed to create the genomic tree is orders of magnitude more data than that used in any previous effort, and the result finally brings clarity to a question that’s been nagging a lot of Hymenopterists: what are the closest relatives of ants?

Probably, bees and spheciform wasps.

That’s not necessarily the relationship I would have guessed, but it holds under multiple modes of analysis.

Here’s the abstract (emphasis mine):

Eusocial behavior has arisen in few animal groups, most notably in the aculeate Hymenoptera, a clade comprising ants, bees, and stinging wasps. Phylogeny is crucial to understanding the evolution of the salient features of these insects, including eusociality. Yet the phylogenetic relationships among the major lineages of aculeate Hymenoptera remain contentious. We address this problem here by generating and analyzing genomic data for a representative series of taxa. We obtain a single well-resolved and strongly supported tree, robust to multiple methods of phylogenetic inference. Apoidea (spheciform wasps and bees) and ants are sister groups, a novel finding that contradicts earlier views that ants are closer to ectoparasitoid wasps. Vespid wasps (paper wasps, yellow jackets, and relatives) are sister to all other aculeates except chrysidoids. Thus, all eusocial species of Hymenoptera are contained within two major groups, characterized by transport of larval provisions and nest construction, likely prerequisites for the evolution of eusociality. These two lineages are interpolated among three other clades of wasps whose species are predominantly ectoparasitoids on concealed hosts, the inferred ancestral condition for aculeates. This phylogeny provides a new framework for exploring the evolution of nesting, feeding, and social behavior within the stinging Hymenoptera.

Source:  Brian R. Johnson, Marek L. Borowiec, Joanna C. Chiu, Ernest K. Lee, Joel Atallah, Philip S. Ward (2013) Phylogenomics Resolves Evolutionary Relationships among Ants, Bees, and Wasps. Current Biology, Available online 3 October 2013. http://dx.doi.org/10.1016/j.cub.2013.08.050

The face of evil?

Charles Darwin argued:

I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars.

-Charles Darwin

There you have it. Parasitic wasps are evidence of a spiteful, uncaring God.

And what does the face of such evil look like? Well…




[what’s this?]


Answer to the Monday Mystery

You didn’t think I’d just hand you guys a full-body shot of a common insect family, did you? Of course not. I am far too clever. The mystery insect, believe it or not, is not a mutillid. Instead, it’s this thing:

Chyphotes sp. (Nevada, USA)

Points are awarded as follows: 2 each to Piotr Naskrecki & Guillaume D for a virtual tie for order, and 8 to “µ” for the correct genus and family. One complicating factor is that this animal is variously placed in Bradynobaenidae or Chyphotidae (see discussion here). Thus, I’m also awarding 4 points to George Waldren for being the first to mention Chyphotidae.

Why isn’t this animal a velvet ant (Mutillidae)? The obvious character is that the prothorax is separate and freely articulated from the remainder of the tagma. In mutillids, the thorax  is fused into a single unmoving shield. In less technical terms, our Chyphotes isn’t a velvet ant because she’s got a strong crease in the middle body segment.

Recent genetic data (Debevec et al 2012) suggest that similarities between the two wingless wasps may just be convergence:

Figure 2 from Debevec et al (2012) shows a maximum likelihood phylogram generated from 4 molecular loci. This arrangement suggests a distant relationship of Chyphotes (yellow) to Mutillidae (pink). Also note the paraphyly of Bradynobaenidae and Mutillidae.

Paraphyly or no, we have arrived at the end of the month. Our monthly winner is Guillaume D., who accumulated 10 points over the course of the month to narrowly edge out Julio Chaúl’s 9 points. Congratulations, Guillaume, email me for your loot!


Debevec, A. H., Cardinal, S., Danforth, B. N. (2012). Identifying the sister group to the bees: a molecular phylogeny of aculeata with an emphasis on the superfamily Apoidea. Zoologica Scripta 41: 527-535.

Answer to the Monday Limerick: Horntail

Tremex columba (Urbana, Illinois).

As many of you surmised, yesterday’s limerick referred to Siricid sawflies, also known as horntails. These insects are wasp-like in appearance, partly because they belong to the same order as wasps, Hymenoptera, and partly because the coloration of some species has converged on wasp-like stripes.

Horntails belong to an older radiation, though, one that never developed the characteristic wasp waist nor the typical wasp carnivory. Horntail larvae feed on dead wood, and the fierce appearance of the adults belies a gentle disposition. The long “tail” cannot sting, being merely an egg-laying structure.

Tremex columba – the pigeon horntail (Urbana, Illinois).

Points are awarded as follows: 5 to Chris Murrow for being the first to pick the suborder, and 5 each to Josh King and Jesse Hardin for being roughly tied here and on FB for guessing Siricidae.


Pison the spider hunter

For those of you who dislike spiders, I’d like to introduce you to your new favorite friend:

Pison mud wasp on her nest (Victoria, Australia)

The genus Pison refers to a small group of crabronid wasps containing about 200 species worldwide. These insects raise their young on a diet of living, but paralyzed, spiders. Paralyzed spiders don’t decay, staying fresh while the wasp grubs eat them alive. It’s a pretty gruesome death, being chewed up in the dark and unable to move. Not that spiders themselves kill humanely. What goes around comes around, I suppose.

While in Australia I photographed one female’s mud nest stuck to the side of a building.  Knocking away drying mud walls reveals the efforts of what I timed to be half an hour’s worth of spider hunting:

A stash of paralyzed spiders.
The Pison egg on a tasty arachnid.

After I disturbed the nest, the wasp rebuilt it and promptly filled the cell with new spiders.

photo details:
Canon MP-E 65mm 1-5x macro lens on a Canon EOS 7D
ISO 200, f/13, 1/250 second
diffuse twin flash

Answer to the Monday Night Mystery

The great black wasp, Sphex pensylvanicus

After some guessing on the part of the commentariat and three visual hints, JasonC finally solved Monday’s psychedelic challenge. For that, I’ll award 5 points. I’ll also give Chris Grinter a point for being the first to guess the correct order, Hymenoptera.

Sphex pensylvanicus, the great black wasp, provisions their larvae with katydids. Adults are often seen hanging around meadow flowers, in this case goldenrod.

A parasitic wasp in elegant electrograph

For a change of pace, some scanning electron micrographs from the braconid wasp project I’ve been working on:

Heterospilus wasp (Costa Rica). Click to enlarge- they're impressive at full resolution!
Close-up of the compound eye.

I’ve had to re-calibrate my sense of imaging to make these pictures. Electron beams do not work like photons, and electron microscopy has a different set of quirks than standard light microscopy and macrophotography. These images are sharp as a tack, at once both more and less real than optical images.

My front yard is a battleground

Now that dog day cicadas are out in full force, their giant wasp tormentors have emerged to gather the bounty. Female cicada killers (Sphecius speciosus) scour the trees for prey to fill their underground burrows, while males jostle for the territories that grant them mating rights.

Sphecius speciosus, male

Several male cicada killers have set up shop in our prairie garden, perching alertly on the flower heads and zooming off to challenge would-be usurpers.

The above photograph, taken in ambient light, was possible because of a thin overcast at mid-day on Friday. The soft lighting eliminated any glare or harsh shadows. As I abstained from my usual foreground flash, the background (mostly Rudbeckia black-eyed susans) was naturally exposed in full color. Light levels were bright enough for a moderate depth-of-field (f/7) at ISO 800 and a fast, 1/200 sec exposure.

Prints of this image can be ordered here (click on “buy” at upper right).

photo details:
Canon EF 100mm f/2.8 macro lens on a Canon EOS 7D camera
ISO 800, f/7, 1/200 sec
ambient light