A Wasp at My Window?

Some of these resemblances are perfectly staggering – to me they are a source of constant wonder and thrilling delight.

Henry Walter Bates, in letter to Charles Darwin, 1861

In one of my nightly checks of the visitors at my screens, a small wasp-like creature caught my eye. But a closer look revealed some interesting details.

Dogwood Borer Moth 1

At first glance, it looked like some sort of wasp (click photos to enlarge)

The patterns and colors looked wasp-like, but the wings, lack of a constricted waist, feathery edges to the back of the wings, and the odd tip of the abdomen certainly did not. I decided it must be some sort of moth that was a mimic of a stinging insect. This type of mimicry, known as Batesian Mimicry, is named after English naturalist, Henry Walter Bates. It is quite common in various insect groups with various types of flies, moths, and some beetles being the leaders in the field around here of wasp and bee look-a-likes.

Many predators that attack bees or wasps suffer painful stings. This is why many have learned to avoid insects with clear wings and yellow and black bands around their bodies. By mimicking stinging insects, the clearwing moths are able to avoid many predators and thus fly even during daylight hours. But, they are also attracted to lights, as was my visitor. 

Dogwood Borer Moth 2

Dogwood Borer Moth

Scanning the field guides I think this one is a Dogwood Borer Moth, Synanthedon scitula. It is a member of the Clearwing Moth family, Sesiidae. I have reported on another group that often are called clearwings, the Snowberry Clearwing and Hummingbird Clearwing moths. But they are members of a different family, the Sphingidae (Sphinx Moths). This species is characterized by transparent wings with some dark scales near tips, a steely blue/black body with yellow stripes on the abdomen, and a rounded anal tuft on the end of the abdomen.

Female moths lay their eggs in wounds on trees. Most of the larvae of this family of clearwings are borers in the limbs, trunks, bark, or roots of trees, shrubs, herbs and vines. The Dogwood Borer Moth’s larvae tunnel beneath the bark of a wide variety of deciduous trees such as beech, hickory, elm, dogwood, apple, and pecan. The galleries made by feeding larvae can cause a lot of damage to the host tree, plus it may give access to other potentially harmful species such as certain fungi.

Dogwood Borer Moth

Dogwood Borer Moth

One reference stated that this group of moths take their deception one step further in that some species have legs with conspicuous tufts of hairs that are tipped with yellow scales. These resemble the pollen baskets on the hind legs of honeybees. He also commented on not knowing the deception value of the prominent tufts of feathery scales at the tip of the abdomen. I was unable to find anything that gave a clear function for these so-called anal tufts, although I wonder if it has something to do with pheromone distribution since they tend to be slightly different shapes in male and females. But, in spite of the tufts, the overall impression of this beautiful mimic is one of leave me alone or else, so, mission accomplished.

2 thoughts on “A Wasp at My Window?

  1. Thank you so much for this and all of the wonderful and enlightening postings of Nature, in all of its sentient expressions! The incredible photographs, paired with the thoughtful and informative commentaries, awaken me to the breadth and depth of this world. Viewing the current posting often leads me to review or discovery of older postings, and a shift in perspective on everything from the looking out of my window to reading the daily news. Thank you for all of your efforts. You are appreciated!

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