Monday, September 18, 2006

Evolutionary wonders

All photos by Lloyd Spitalnik

Insect #1.

Insect #2.

At first glance [and perhaps at tenth glance] you might think that the two insects above are closely related. You may already know that insect #2 is a wasp, Ancistrocerus adiabatus, since I posted it here a few days ago and pointed out the "smiley face" on its thorax. Consequently you might think that insect #1 with the V on its thorax is also in the wasp family [Hymenoptera].


The first insect, photographed last Saturday at Turtle Pond is not a wasp. It is a syrphid fly, Spilomyia longicornis and belongs to the Fly or Diptera family.

Many Syrphid flies mimic bees or wasps in appearance. This is an example of Batesian mimicry, which protects them from falling prey to birds and other insectivores who would normally avoid eating true wasps because of their sting. Evidently the animals that are fooled by these wasp mimics cannot count, for a Syrphid fly and a wasp can be distinguished by the number of their wings. All flies have only two wings, [Di = two, Ptera = wings] while the wasps and bees these are mimicking [and indeed most other insects] have four wings.

Batesian mimicry, by the way is named for Henry Walter Bates, a British scientist who studied mimicry in Amazonian butterflies during the mid- and late nineteenth century. It refers to two or more species that are similar in appearance, but only one of which is armed with spines, stingers, or toxic chemistry, while its apparent double lacks these traits. The second species has no defense other than resembling the unpalatable species and is afforded protection from certain predators by its resemblance to the unpalatable species, which the predator associates with a certain appearance and a bad experience.

Below are a few other stunning photos of some insects in Central Park taken by Lloyd a few weeks ago.

Blue Dasher [female]

Weevil Wasps [mating]

Ailanthus Webworm Moth
[yes, it's a moth]