This is not a Scorpion or a Fly! (Scorpionflies!)

Insects for Fun!

This week we look at one of the strangest flying insects out there and their behaviors. There are many kinds of scorpionflies and they are all pretty different.

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Richard Smithson, Cubase, Mondo Loops, Sátyr

Transcript:

Welcome back to episode 50 of Insects for Fun! The weekly podcast covering all things entomology. This week we are looking into a very interesting type of fly which is actually not a fly at all, and kinda seems more like a chimera than anything else!

Intro:

Scorpion flies are a group of insects belonging to the order Mecoptera which means long wings, but the wings are not the most interesting thing about these insects. There is one family in particular called panorpidae, and the males in this family have an abdomen which curves upward and has a large bulb-like structure with a pointed tip at the end. This family has the most species and is the main reason why Mecoptera are often referred to as scorpionflies. That being said, those showy and intimidating tails are only for mating, and can’t harm you or anything else. Another really wacky feature for these insects would be their long mouths.The heads are actually small but the mouth itself is really big. The term for a mouth like this is called a rostrum which I mentioned in the Acorn weevil episode!

As for the wings, they are heavily veined and have a more primitive appearance as if they came from a Mayfly. I really can’t stress enough how strange these insects look, it’s like someone just took random parts from different insects and put them together into this monster we call a scorpion fly.

The distribution for these is worldwide but the diversity is strangely separated. For example there is more variety at a species level within Africa, and the European continent, but there is greater variety in families and genera in the Americas and Australasia.

And not all of these scorpionflies look this weird. There are 9 families within the order, and each one looks pretty different. For example one family called Bittacidae look like four winged crane flies and are often referred to as hangflies or hanging scorpions. Another family called Boreidae look more like fleas or even the flightless midge found in antarctica.

Life Cycle, and food source etc:

In general scorpion flies prefer more humid environments in forests and grasslands surrounded by broadleaf vegetation like oak trees or other shrubbery with flat leaves to rest on. These insects feed on everything from honeydew and nectar to dead or dying organisms. Many of them actually snatch prey out of spider webs which is really cool!

Some though are carnivorous scavengers that prey upon smaller insects and sometimes even spiders. The hanging flies mentioned earlier are in this camp and have a really cool method for catching prey. These flies literally hang on the edges of plants with their legs dangling down and they grab insects mid flight to feed on.

The life cycle for these insects is holometabolous which means that they have a larval and pupal stage. The larvae for scorpionflies actually resemble caterpillars and spend their time in the ground feeding on decaying matter and other small insects except for one special family found in New Zealand, Australia, Tasmania, Chile and Argentina. This special family called Nannochoristidae have aquatic larvae that prey on smaller animals in riverbeds. They are also believed to be one of the only larvae that have true compound eyes, which is wild because compound eyes are known to be a special trait in adult insects (insert naruto quote)

I can’t speak for every scorpionfly out there, but in general these have one generation a year with the pupae staying dormant during the winter months.

Females lay their eggs in the soil, and require a certain moisture level in order for eggs to hatch in a timely manner. This is not uncommon with insects that develop in the ground, such as beetles and cicadas etc. And if the moisture levels are off it can delay the hatching of scorpionflies up to months.

Behaviors:

When it comes to mating, Scorpion flies have some interesting rituals, and they usually involve offering a female some kind of incentive to woo her. For example, common scorpionflies which are the crazy monster looking ones have three separate tactics for luring a mate. The first two are to offer wads of spit or a dead arthropod (super enticing I know). Though sometimes they try to mate without offering anything! (gasp) (those pigs).

Apparently the practice of giving a female a gift is for distracting the female resulting in longer mating time. I personally think this is hilarious, and it reminds me of the safari zone tactics in pokemon games where you throw a berry or w/e to increase your catching odds and prolong the encounter.

Hanging Flies use pheromones to lure a female, and then offer them a special hostage. But as great as some males are, there’s a lot of competition, and these flies have to get crafty sometimes. Scorpionflies are known to sometimes mimic the behaviors of a female in order to take gifts from other males, sometimes they also just show up for sloppy seconds. They literally wait around for a new female to fly into the area and then present her with whatever is left from the previous male's gift. That’s literally showing up to someone else's date after they left, taking the flowers or whatever chocolate is left and handing it to a new girl (How you doin?). The worst part is this actually works, a lot…

Now of course each family of scorpionflies has their own quarks and gimmicks as well, for example the wingless snow scorpions in the family Boreidae which are the flea looking fellas just jump on a female and stay on them for up to 12 hours, just chillin there. Literally and figuratively these cold climate scorpion flies just go about their usual day after pairing by moving around and feeding while the females do absolutely nothing.

Defenses and Predators:

Scorpionflies aren’t really known for having any special defenses, and as a result I was unable to pull up anything in regards to how they protect themselves from other insects or insect eating animals, but! I was able to find something interesting in regards to their preference for dead animals. Scorpionflies are actually now used by forensic entomologists because they are one of the first responders to a decaying human body, even before the much more famous blowflies which I mentioned in my forensic entomology episode.