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Batesian mimicry

Survival Through Mimicry: The Viceroy Butterfly

The survival of Viceroy butterflies in all of their life stages is significantly enhanced by mimicry.  A Viceroy egg resembles a tiny plant gall.  Both larva and pupa bear a striking resemblance to bird droppings.  And the similarity of a Viceroy to a Monarch is well known. For years it was thought that this mimicry was Batesian in nature – a harmless organism (Viceroy) mimicking a poisonous (Monarch) or harmful one in order to avoid a mutual predator.  However, recently it’s been discovered that the Viceroy butterfly is as unpalatable as the Monarch, which means that  mimicry in its adult stage is technically Mullerian – both organisms are unpalatable/noxious and have similar warning mechanisms, such as the adult butterfly’s coloring.

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Bumble Bee-Mimicking Robber Flies

7-10-19 robber fly 0U1A0212Robber flies are a special group of predatory flies that possess stout, spiny legs, a dense moustache of bristles on the front of the head (mystax) that protects the robber fly’s head when it encounters struggling or stinging prey, and three simple eyes in a depression between two large compound eyes.

Certain robber flies resemble bumble bees. The evolutionary advantages of a harmless organism mimicking a harmful organism (Batesian mimicry) include deterring predators that are fearful of stinging bees. In addition, it also makes it more likely that a potential prey insect will come closer to the bee mimic, thinking the “bee” is looking for nectar or pollen, not a meaty meal.

A quick way to distinguish a robber fly from a bumble bee is to look at the antennae and wings. Flies usually have short, stubby antennae; bees, including bumble bees, have “elbowed” antennae (an obvious joint). Flies have two wings, while bumble bees (and most other insects) have four. The pointed, stout proboscis, bearded face, fleshy feet and long, tapering abdomen of robber flies are also identifying characteristics. (Photo: Laphria thoracica piercing a click beetle between the beetle’s hardened outer wings (elytra) in order to inject enzymes which will eventually allow the robber fly to drink its prey.)

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Mantisflies Preying

7-16-18 mantisfly2_U1A1975

There is a small group of insects (family Mantispidae) known as mantisflies, so-called because of their resemblance to small praying mantises. Climaciella brunnea (pictured) is the most commonly encountered mantisfly in the Northeast. Not only does it have the grasping forelegs of a praying mantis, but it also mimics a paper wasp.

A newly hatched Climaciella brunnea larva attaches itself to an arachnid host, preferably a wolf spider. It lives off the blood of the spider until the spider lays eggs, and then the larva positions itself so that it gets wrapped up in the spider’s egg sac along with the eggs.   Once inside the sac the larva feeds on the eggs until it pupates. The adult mantisfly emerges and preys on other insects, often those visiting flowers, and consumes nectar and sap as well. Although they lay an enormous number of eggs, mantisflies are relatively rare.

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