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| Not a bee, but a mimic, the fly Eristalis. © Beatriz Moisset |
A stroll among the flowers allows me to
see numerous bees of different sorts, zipping along from blossom to
blossom. Just as numerous are other winged insects that look very
much like bees. The experienced eye recognizes them for what they
are, flower flies impersonating the stinging insects. But those
unfamiliar with bees or with insects, in general, may assume that
these flower flies are bees. They may even recoil in fear of a sting
although the flies are innocuous, lacking such powerful weapon.
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| A wasp mimic, Spilomyia sayi © Beatriz Moisset |
Those flies who imitate bees or wasps have a reason
for playing this masquerade. They are not interested in fooling us,
humans. Their deception is aimed at their predators, mostly birds.
However, the ruse is so effective that it even we fall for it.
Syrphid flies, also known as flower
flies or hover flies, are almost as assiduous in visiting flowers as
bees are. They drink nectar and sometimes also feed on pollen.
Although not as efficient as bees as pollinators, they deserve some
credit and occasionally their contribution to pollination is
significant. Another group of flies that visit flowers with great
frequency includes the so called bee flies.
Both, flower flies and bee flies mimic
bees or, in some instances, wasps. The imitation is very specific in
some cases. The so called drone fly, Eristalis tenax, looks
like a honey bee. The name is appropriate, considering that male honey bees, drones, have large eyes, and these flies have even bigger
eyes. Both, the fly and the honey bee are European. The imitator
evolved along with its model in that continent. Another European
flower fly that mimics honey bees effectively is the narcissus fly,
Merodon equestris.
Other flower flies and also a robber
fly imitate bumble bees. They have a furry coat and even buzz like
bumble bees.
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| Bumble bee mimic, Mallota bautias © Beatriz Moisset |
The smaller flies, members of the
Syrphinae subfamily apparently are mimics of some or another of the
many solitary bees. In most cases one cannot be sure of the model
chosen for this mimicry.
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| A honey bee, the model for many mimics © Beatriz Moisset |
It is a peculiar thing that some
imitations are extremely good, while others are rather general in
character. Biologists speculate that even a not-so-good imitation may
serve the purpose of deceiving the enemies and this is why such types
of mimicry persist in nature. It is also possible that the predators
don’t see exactly what we see and the mimicry is convincing enough
for them.
This is just one type of mimicry. Other
insects take the appearance of their surroundings, which makes them
nearly invisible. Still others look like bird poop, not an appetizing
sight for a snack seeker. Stay tuned for descriptions and
illustrations of more of these ingenious survival mechanisms.
References
