What if William Shakespeare was an entomologist? If he had been, the famous sword soliloquy from Macbeth might describe a moth, rather than the murder of a king: 

Is this a dagger which I see before me, 

The handle toward my hand? Come, let me clutch thee. 

I have thee not, and yet I see thee still. 

Art thou not, fatal vision, sensible 

To feeling as to sight? Or art thou but  

A dagger of the mind, a false creation, 

Proceeding from the heat-oppressed brain? 

The daggers that might have inspired a more insect-interested individual would have been a group of moths in the genus Acronicta. Acronicta is derived from Greek roots meaning “the beginning of the night” and would describe the nocturnal nature of these moths. 

In a doorway recently, I observed one particular member of the genus, Acronicta lobeliae, likely attracted by a light shining through the glass door but neglecting to hide itself away when daylight came.  This dagger moth, also known as the greater oak dagger moth, is a common — if not elusive — night flyer. 

Though first described in the scientific literature by French lawyer and entomologist, Achille Guenee in the mid-1800s, he might have missed the mark on its nomenclature. We don’t know what connection Guenee saw between the moth and lobelia but it seems a misnomer now, as this dagger moth has a clear penchant for oak, even though the original designation has stuck. 

The medium-sized moth is gray with black dagger-like slashes on its wings, which likely helps it camouflage itself when up against the bark of a tree. As a caterpillar, the oak dagger moth also exhibits mimesis—the mimicking of another organism—appearing to be a twig on its favored oak tree. To add to the confusion, with every instar (the phases between each molting), these caterpillars can have a distinctly different look in terms of body shades, eyespot colors and amount and density of body hair. 

A nighttime pollinator, the oak dagger moth adult will consume pollen from various flowers. As a caterpillar, it only has eyes for oaks and is a specialist when feeding, going primarily for oak leaves.  This dagger moth can live harmoniously with those oaks and generally will not completely defoliate the trees. Live and let live is this daggers way for its foodstuff but not for its enemies. 

As a caterpillar, the oak dagger moth has long hairs that can deliver a mild neurotoxin if touched. Another way to dissuade its enemies is through the production of sound when the adult moth rubs its mandible together. With up to two broods per year and a robust food source—even if some are lost to birds and other creatures—there will likely be enough to keep the species going. 

Even with the many moths that these generations produce, there is no guarantee you will see this cloak and dagger species. On the other hand, as Shakespeare reminds us, “Howe hard it is to hide the sparks of nature!” 

Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown, and author of Martha’s Vineyard: A Field Guide to Island Nature and The Nature of Martha’s Vineyard.