Look alikes (… or why mimicry works)

Recently, I have misidentified a few critters in the field, only to realize what they really are when I begin editing them on the computer.  For example,

Not a Monarch!

Not a Monarch Butterfly!  Though this Viceroy looks like one, there is a faint black line on the hind wings that is absent in Monarchs, and Monarchs have many more white spots on the leading edge of the forewing.

From:

Viceroy butterflies tend to be smaller than Monarchs, but this is difficult to determine in the field without both present.  From:  Learner.org

Milkweeds have their own set of orange and black insects, some of which are distasteful, but most of which are simply mimicking the color patterns of the noxious individuals (like the Monarch butterfly).

milkweed insects

It’s probably no accident that Box Elder bugs also cash in on this Milkweed mimcry complex, copying the pattern of the Common Milkweed Bug (top right above).  It is also about the same size as the milkweed bug.

Boxelder bug

Boxelder bugs are considered pests, as they congregate by the hundreds in our window sills in the fall.  (Photo from the National Pestcide Information Center)

And then there is the “bee complex”.  Everyone wants to copy the yellow and black pattern of the bees and wasps, cashing in on the threat of a painful sting.

The things that sting have bright yellow and black coloration; some have fuzzy hair and some don't -- even that pattern is copied.

The things that sting have bright yellow and black coloration; some have fuzzy hair and some don’t — even that pattern is copied.

The mimics might even try to act like their models -- hovering in front of flowers (hoverflies) or between perch sites (robberfly)

The mimics might even try to act like their models — hovering in front of flowers (hoverflies) or between perch sites (robberfly)

There are obvious advantages for the mimic — gaining protection from potential predators who have learned that certain color combinations mean distasteful and/or dangerous prey.  So, the nectar-loving, innocuous hoverfly seemingly poses a threat to would-be consumers of these bite-sized flies.  This is an example of Batesian mimicry, where the model is toxic, but the mimic is not.

But in other cases, the mimic is just as distasteful and perhaps as lethal as its model.  Naive Bluejays offered Monarch or Viceroy butterflies (sans wings) didn’t like either one of them and regurgitated their meal.  Many species of bees and wasps similarly utilize the yellow and black warning coloration.  These are examples of Mullerian mimicry, where the mimics and their models are both unpalatable or dangerous.  What is gained with this type of mimicry most likely is reinforcement of the warning to potential predators, who because of one bad experience with a particular individual prey item, avoid anything that looks like that in the future.

There are many websites devoted to this topic; one of the more interesting (from Discover Magazine) can be found here, where you can read about other uses of mimicry in the natural world, like:

Orchid flowers fool flat-footed flies by faking fungus-infected foliage

Is this plant diseased?  Or is it disguising itself with fungal spots to lure in potential pollinators?

Is this plant diseased? Or is it disguising itself with fungal spots to lure in potential pollinators?  From Discover Magazine blogger, Ed Yong.

5 thoughts on “Look alikes (… or why mimicry works)

  1. Wonderful post, Sue. This summer I have already misidentified a number of species because of mimicry, including a Viceroy butterfly. The more I looked into the topic, the more complicated it became, so I appreciate the way in which you have sketched out some of the different types of mimicry. Mimicry seems to fall under the general category of defense mechanisms and one of my favorite explanations of that whole category is at http://www.cals.ncsu.edu/course/ent425/tutorial/Ecology/defense.html .

    • Thanks, Mike, that is a great general reference website. It is a complicated topic, but you begin to see general pattern emerging as you encounter more examples of similar strategies.

  2. I’ve been wondering about the hummingbird moths in my monarda – how much of their similarity to hummingbirds is convergent evolution and how much is mimicry. In some pictures I snapped you can even see a little fringe on the abdomen that looks like (or perhaps works like) a hummingbird’s flared tail feathers.

    • What great photos of the moths, hovering in front of flowers! Thanks for including the link. I would say this is not an example of mimicry (which tends to be for defense), but rather a good example of convergence on the best method for feeding on nectar while suspended in air. Humming-moths are unlike other moths in feeding in the daytime, hovering to feed, and in having rather long wings (for a moth), as well as those short scales on their abdomen that look like they serve as a tail rudder. So there have been a lot of changes in behavior and anatomy to converge on the hummingbird feeding mode. Or perhaps it is the hummingbirds that have converged on the moth’s feeding strategy…

  3. Pingback: Not a bee…or a wasp | Back Yard Biology

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