Pest ControlWhat's This Bug?

What’s This Bug? The Scorpionfly

Brought to you by ARBICO Organics

Insects are masters of illusion and the Scorpionfly (Order: Mecoptera) is an excellent example of this. This bug may look like a devilish mashup of a scorpion and a wasp that could seriously hurt you, but it’s so not that.  It’s none of those things and, in fact, is completely harmless. Scorpionflies cannot sting and do not bite. And that large stinger-looking thing? It’s actually the oversized genitalia of the male. The female is much less intimidating, as you can see in the picture below. Now you’re looking at this insect completely differently, aren’t you?

Scorpionflies are not actually flies, but they are nearly as common with more than 500 species in five families worldwide. Of those, 68 species are in North America. One or another of this large family can be found in all kinds of habitats – there are even Snow Scorpionflies. Despite being nearly everywhere, scorpionflies are not familiar to most people. This may be due to their small size (½” to 1” in length), or to their lowkey lifestyle. Scorpionflies are generally scavengers and feed on dead or dying insects (although they take a sip of nectar on occasion); but, there are some species that prey on easy pickings, like wounded or slow-moving insects. Scorpionflies are also said to steal bugs from spider webs, but this behavior is probably as brazen as these little guys get. For the most part, they hang around (literally, they hang) on leaves and branches until they have an opportunity to feed. 

Scorpionflies claimed their place on our planet a very long time ago and have carried on ever since. They developed during the Permian Period 250-300 million years ago. This was a time of great climate change and mass extinctions due to intense volcanic activity. These insects persisted, however, and have changed very little between ancient and modern times. They are believed to be the ancestors of flies, butterflies, and dragonflies. This time period also saw the rise of the cockroach, an insect that most people probably wish had not survived the volcanoes.

So, what about that big “tail”? Like other male creatures with flashy parts, it’s used in courtship display. They wave it around while emitting pheromones to get the attention of females. But he must have more than a big tail to win the female over; he needs to offer her a nuptial gift. These gifts are either dead insects or a saliva ball that, if she accepts him, she’ll feed on while copulating. Just in case she changes her mind, he has claspers on his huge appendage that keep ahold of her. And if she goes through her food gift too fast, he will hack up another saliva ball for her to eat. These methods to subdue and placate her are necessary as the females have been known to eat their suitors.

Another probable reason for such an ostentatious tail-end is Batesian mimicry. This is when a defenseless animal takes on the characteristics of more threatening or unpalatable creatures. In the case of the scorpionfly, their black, yellow, and orange coloring is like a wasp. When you add the stinger-like appendage, you have a harmless animal that looks like a dangerous scorpion-wasp hybrid. This is an excellent strategy to keep predators (and some humans) away. But is also what causes witless humans to kill something peaceful for looking like something else.

Keep an eye out for these little guys, they’re out there doing their part to clean up organic matter. Be gentle with them, though; they’re survivors but also very delicate.

Pam Couture is the Lead Content Writer at ARBICO Organics. She lives in Tucson, Arizona, where she is surrounded by family, friends and nature. ARBICO Organics can be contacted at 800.827.2847 and you can visit their website at

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