Butterfly or Moth? The Skipper Family (Hesperiidae) is a Little of Both

A member of the Grass Skipper family drinking nectar
Photo by Brad Sylvester, copyright 2011, all rights reserved

As we learn new skills, we keep them sharp by putting them to use. So let’s use our butterfly or moth checklist on this fellow.

First, it has a dull brownish color which would tend to make it a moth. It holds its wings upright when at rest which says butterfly. It is active in the daytime, which says butterfly, and the antennae are not feathery, but they end in a club-like thickening. The body is thick and hairy which says moth, and the head is oversized for a butterfly which says moth again. What do we do when our checklist of butterfly versus moth indicators is split down the middle?

While none of the checklist indicators are 100% accurate, because of some rare exceptions, the most accurate is the antennae structure. So, to start with, we’ll operate on the assumption that it’s a butterfly, but to be sure, let’s start at the Order level of Lepidoptera which includes both butterflies and moths since we’re certain that it’s one or the other.

There are two ways to start narrowing it down.  We can thumb through the butterfly and moth pictures in our field guide until we find a picture that matches or comes close. Using that method we find that the closest match is the silver-spotted skipper, but there are some distinct pattern and color differences which rule out this particular species, but there are enough shared traits that we start to focus on the skipper family which contains many different species, although my Audubon Field Guide details only a few.

My other favorite source is bugguide.net. From the main page, I click the butterfly picture on the graphic selection plate at the top left. That brings me to Papilionoidea (Butterflies excluding Skippers). Whoops. Let’s back up.  Near the top of this page there’s a complete taxonomic trail leading to Papilionidea. By choosing the next rung up the ladder, Order, we get to Lepidoptera (Butterflies and moths). About halfway down that page we get to Identification. Ah-ha! There are three listings: Moths, Butterflies, and Skippers. Although skippers are butterflies, they are a separate group with their own taxonomic family (Hesperiidae).

From there, I’m reasonably confident that it belongs to the sub-family of Grass Skippers (Hesperiinae). However, I can’t make a positive identification at a lower level than that. I can rule out many Grass Skippers, but I can’t pin it down. I think it is probably a Little Glassywing Skipper (Pompeius verna), but may be a Northern Broken-Dash Skipper (Wallengrenia egeremet). It looks very much like a three-spotted Skipper except the short antennae disqualify it as does the range. It looks like a Eufala Skipper as well, but again the range is a disqualifier.

• ·         NHPTV list of Skipper species that live in New Hampshire

Grass Skippers feeding on flowers in July
Photo by Brad Sylvester, copyright 2011, all rights reserved.

To make matters worse, I believe that I actually photographed as many as three separate Skipper species all flitting among the same flowers. I’ll detail the other two another day. There’s an old saying: Discretion is the better part of valor. Well, that saying applies equally well in trying to classify animals or plants. Sometimes you just can’t be sure based on the available information. That’s ok. A partial identification which gives the reasons why you can’t go further is better than making assumptions or guesses based on incomplete data.

Our taxonomic classification for the creature photographed on this page is:

Kingdom: Animals

Phylum: Arthropods

Class: Insects

Order: Butterflies and Moths (Lepidoptera)

Superfamily: Skippers (Hesperioidea)

Family: Skippers (Hesperiidae)

Subfamily: Grass Skippers (Hesperiinae)

Genus: either Pompeius

              Or  Wallengrenia

Species: either Little Glassywing Skipper (Pompeius verna)

                     Or   Northern Broken-Dash Skipper (Wallengrenia egeremet)

Miscellaneous observations:

These Grass Skippers are one of the few buterflies that actually make a buzzing sound when they fly at speed. This may have something to do with the wing arrangement. The fore and hind winds separate out and may be held at different planes while at rest. This posture is somewhat common among skippers, although it was rarely displayed among the group in my yard.

Grass skippers showing two different resting wing postures
Photo by Brad Sylvester, copyright 2011, all rights reserved

Quick facts about Grass Skippers:

Diet: Caterpillars eat grasses and sedges. Butterflies drink nectar - in my yard these species were dining on cone flowers (as show in the top picture) and appeared to prefer Blazing Stars Kobold (Liatris Spicata) where they were feeding in a group of about 15 or more individuals.
Range: varies by species
Habitat: Since the caterpillars feed on grass and sedges, they prefer open areas. Individual species may be particular about the specific species of grass that they eat.