Fall is a time when lots of insects get active, sometimes it seems, even more so than in the summer.
Fall is also the time for many late blooming wildflowers, and what more perfect of a place to find insects than on flowers. While taking a walk at a nearby park I came across a couple different types of wasps and some cool beetles. The two wasps had very different markings on them so I assumed they were different species….but what species were they? The nifty yellow and black beetle was really cool but it left me wondering…what species was it? How can I identify these insects?
Taxonomically insects are a Class of organisms ...do you remember taxonomic classification from 7th grade biology… (Domain), Kingdom, Phylum, Class, Order, Family, Genus, Species. King Philip Came Over From Great Spain or Dumb King Phillip Came Over From Great Spain?
The idea of taxonomy and classification using this system relies on the observation that at all individuals within a taxonomic category share certain characteristics that make then different from others. For instance all individuals within a species share traits that make them different from individuals of another species, all species that belong in a genus share particular traits that species in different genera do not share, and all members of a family share traits that differentiate them from other families, etc. All animals belong to the kingdom Animalia, and insects are members of the animal phylum Arthropoda, which means jointed (Arthro) foot (poda) or jointed leg. All members of Arthropoda (insects, spiders, scorpions, crustaceans like lobsters and shrimp) have multiple pairs of jointed legs. They also have an exoskeleton, a hard outer covering that protects their internal organs and provides support and structure. This differs from other animals like us humans which have an endoskeleton made of bones and a cartilage and is internal (endo) to our body. So an exoskeleton and jointed limbs helps differentiate arthropods from other animals, but what makes an insect an insect? Taxonomists like to organize and categorize things, sometimes they need additional levels of classification beyond the 7 or 8 I initially mentioned. They like to have “sub” things and “supra” things…Like Hexapoda which is a “sub”-phylum consisting of all arthropods with six (hexa) legs (poda). Finally! Within Hexapod we have the Class Insecta….so what is an insect?
Well we can say that according to this definition, spiders are NOT insects, because they have 8 legs and not 6, spiders belong in a separate group of arthropods. Another trait that all insects share is that they have 3 main body parts (a head, a thorax and an abdomen) that are clearly segmented or separate from on another. This differs from other arthropods (like spiders) which have their head and thorax combined into one segment (the cephalothorax).
As an undergraduate majoring in zoology, I had lots of “ology” courses I could take….and I always wondered why anyone would be interested in entomology (the study of insects), I mean cockroaches …yuck! And then I took the course…..and I was forever changed…..
Insects are an incredibly diverse group, with over a million species described and millions more undescribed. With that kind of diversity who wouldn’t want to study them?!?! I mean mammalia, the class that we mere humans are a part of only consists of 5,500 to 6,000 species, mammals are sooooo boring!
Like anyone else who has taken at least one entomology course, I love correcting people on their insect misidentification…
When someone calls a spider an insect, I shudder …have you no shame?
Or when someone calls anything they see flying around a fly…do you NOT know about Dipterans?
Dipteran …the true flies! And you thought a house fly was a house fly was a house fly.
Dipterans (like your house fly, horse fly, mosquitos and crane flies) have one functional pair of wings and the other pair is now reduced in size and used as a sensory organ to help the flies maneuver better in flight. And what about those crazy Dipteran flies that mimic a completely different order of insects the Hymenoptera (bees and wasps)? Ever been buzzed by what appears to be a yellow jacket only to have your entomologically-minded friend tell you it is just a fly…and how did they know? Take a look at its wings (only one pair) and its eyes, most Dipterans have huge eyes covering most of their head, and Dipterans have short stubby antenna, not long, jointed ones like most bees and wasps.
But enough about flies because this months post is about two wasps and a beetle.
I could identify the two wasps to their order Hymenoptera (which means membranous wings) Hymenoptera have two pairs of wings and if you get close enough to look, you will see that their forewings are connected to their hindwings by a series of small hooks.
And I could identify the beetle to the order Coleoptera which have a hardened shield-like pair of forewings that protect their membranous soft hindwings.
But that was as far as I could get to…so I turned to a cool app called iNaturalist to get some help. With iNaturalist you can upload a picture along with location information and post your observation.
Within a couple of days my pictures had preliminary identifications, members had identified my two wasps as belonging to the Scoliidae family of wasps
Here are two pictures of the same wasp, this is the double banded Scoliid wasp, Scolia bicincta. See the two parallel pale bands on its abdomen?
This is the two-spotted Scoliid wasp (Scolia dubia).
Scoliid wasps are generally black wasps with bluish/ black wings and yellow markings. They are solitary meaning they do not live in hives or colonies like paper wasps or yellow jackets. They are parasitoids of beetles. The female will find the grub like larvae of a beetle, move it into the wasps' underground burrow, paralyze the larva and then lay its eggs on the larva. The young wasps then feed off of beetle larva, eventually killing their host.
As for the beetle I found, the best identification was the Amorpha borer (Megacyllene decora). Like other borer beetles, this beetle lays its eggs on a host plant (in this case the false indigo plant (Amorpha fruticosa) and the larvae burrow and eat the wood before turning into adult beetles. The adults are often found on Goldenrod and Boneset in the fall.
An adult Amorpha borer beetle (Megacyllene decora)
Identifying the species of organism you have can be tricky, many species look very similar so morphological traits cannot always be reliable. Furthermore given the diversity of organisms, many groups are still understudied and many species are undescribed. The iNaturalist app is nice to use, but asking a trained taxonomist to identify a species is the best way to get the most accurate identification.....if you can find one. Nevetheless, I was happy with the identification of my insects with iNaturalist, they seem the most likely match.