Naturespeak A naturalist's view of the world

August 24, 2013

That is the Question

Filed under: Uncategorized — wykes @ 9:42 am

Nature is often all about split second decisions. It is both efficient  and “smart” to look like something else without actually being that something else (take for example of the effectiveness of photo cardboard cut-out cops used to “patrol” some potential crime spots – no donuts required). Predators and prey usually only get glimpses of each other before making their move to grab or go. With that in mind, collective evolutionary trends dictate that appearances really do count and that it is o.k. to fake it as long as it improves survival odds. It is hard to tell what is real in nature.

Although there are examples of mimicry in every layer of the natural world, insects really have this gig perfected. Countless species of Insects mimic everything from harmless poo to venomous beasts and they do so from both sides of the fence, and often on both sides at once (what?).  I put before you two examples from the realms of my back yard – a fly and a moth that pretend to be bee-like. Thus the question “A bee or not a bee.”

The first faker comes in the form of a bumblebee. It is a hairy thing adorned in black and yellow and from a short distance looks very bumbly indeed. It is, of course, not a bee at all but a type of Robber Fly of the genus Laphria. A close look will reveal that the resemblance is only fleeting.

Robber Flies are robust predators that aggressively pursue, and suck dry, all manner of insects. They are the dragonflies of the fly world – perching in open sunny spots and flying out to grab passing prey. As a group they tend to be rather slender and this Bee-mimic Robber is much skinnier than your average (healthy) bumblebee. Flies only have one pair of wings while bumblebees have two pair. The imitation sports short spikey antennae as opposed to the bent appendages of the real bee. The face is long and mustached and the facial fuzz covers up the deep divide between the two huge compound eyes (bumbles have rounded heads).

It is also worth noting the large pad-equipped feet with large hooked claws on the Robber fly in question. This is a decidedly un-bumblelike trait that the fly uses to secure prey.

The benefit incurred by being a bee imposter is that it might deter other predators from tackling what they perceive as a sting- laden beast. This is the “sheep in wolf’s clothing” scenario. Because the Bee mimic Robber Fly is a wolf, however, it also probably benefits from the “wolf in sheep’s clothing” scenario as well.  The extensive prey list of this fly includes a hefty dose of real bees and bumblebees. There is the possibility that looking like a bumble helps this predator get closer to its intended prey. “Hey,” the surprised bumblebee screamed in horror, “you’re an imposter, you, you… (end of conversation punctuated by sucking sounds).

The second mimicking insect I will present comes from the moth world (see below and here). It is a stem borer that comes from a group of moths known as the Wasp Moths.  These guys employ slender partially transparent wings, long slender abdomens and enhanced yellow antennae.  They even fly about in the bright sun of daytime (there would be no need for such a cover if it retained nocturnal habits.) Over all this dark species is mimicking a metallic black paper wasp. Not exactly an academy award winning performance but enough to warrant a role as a character player.

The Wasp mimic Borer is strictly in the realm of “sheep in wolf’s clothing” mode. As a nectar feeder it seeks flowers and cannot defend itself. By looking like a wasp, it is given a degree of protection by signaling “I’m packing a powerful sting.”

Of course, this threat would not deter a Bee-mimicking Robber Fly one wit. So, even though I was not witness to such a meeting, it is very likely that these two cross-dressing insects met and that the fake bee won out over the fake wasp. Real life can be a grand illusion.

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