Bug of the Week
Skippers (Family Hesperiidae)
The BugLady has confessed in these pages that she is “Skipper Challenged.” Skippers (Family Hesperiidae) are sun-loving, chunky, hairy, small-sized, large-headed, often brown/brown-and-orange butterflies that are sometimes mistaken for moths. Like other butterflies, their antennae have club-shaped tips, but in most skippers the clubs have a tiny hook on the end. The males of most species have a patch of dark colored “scent scales” (a stigma ) on the forewing that produces and dispenses sex-attractant pheromones (sometimes the scent glands are located within a fold in the forewing). Other kinds of butterflies have scent scales, too.
Skippers are called skippers because of their “skipping,” darting flight. According to the Butterflies and Moths of North America website (http://www.butterfliesandmoths.org/), “More than 3,500 species [of skippers] are described, with approximately 275 in North America, many of which are found only in Arizona and Texas.” Skippers are important pollinators.
Taxonomically, North American skippers are divided into five sub-families – the Spread-wings and Firetips, the Skipperlings/Intermediate skippers, and the Dicot, the Grass, and the Giant skippers. One of today’s skippers is in the Spread-wing skipper bunch and the other used to be but is now in the Dicot skipper bunch (depending on whose book you read).
The folks at the excellent Butterflies of Massachusetts organization have compiled 150-plus years of butterfly data, including annual dates of first emergence, the average flight periods, abundance, range, and anecdotal notes. Their recent Juvenal’s Duskywing and Northern Cloudywing data suggest that “earlier flights and possible partial second broods indicate that this butterfly will adapt easily to climate warming and probably remain common .”
Juvenal's DuskyWings are in the Spread-wing bunch of skippers (sub-family Pyginae), and as their name suggests, they tend to bask with their wings spread, held in the same plane (though they may sleep with their wings tented, moth-like, over their back).
These are late spring butterflies of oak edges, fields, and roadsides east of the Rockies. Their wings are sooty brown with lighter mottling, and their wingspread is one-and-a-half inches, plus or minus. The feisty and territorial males perch and patrol at the edges of clearings, awaiting females, and JDs also like to sit on the ground. Females lay eggs singly on oak leaves, and when those eggs hatch, the caterpillars eat the new oak leaves and rest inside other oak leaves that they roll or fold and fasten with silk. JD caterpillars mature by early summer and then aestivate (rest) until fall, waking in time to fashion a leaf into a hibernaculum and line it with silk. When spring comes, they emerge from one leaf shelter, make another, pupate in it, and transform into adults. Check out the spectacular JD caterpillar: http://bugguide.net/node/view/149511 .
Adults nectar on late spring wildflowers (though one source said that they eschew blossoms and get nutrients from animal droppings and carrion).
According to the Butterflies of Massachusetts site (www.butterfliesofmassachusetts.net/), the JD is “one of the earliest butterflies to be described as a species.” At one time , the convention was to name duskywings after Classical Roman dignitaries, so JDs were joined by Horace, Propertius, Pacuvius, Persius, and Afranius duskywings, and two others that celebrate the Old Guard in their Latin names.
There’s a great series of pictures in David L. Wagner’s Caterpillars of North America that shows how the tint of a late-season JD caterpillar may change as its oak leaf shelter reddens.
Some sources continue to lump the Northern CloudyWing (Thorybes pylades) with the Spread-wing skippers; others place the cloudywings in the new “Dicot skipper” sub-family Eudaminae. “Dicot” refers to their caterpillar food plants (the BugLady is certain that BugFans recall learning about the two great groupings of plants – the Monocotyledonae and the Dicotyledonae) . Caterpillars of the Grass skipper bunch mainly eat grasses and sedges (monocots); Eudaminae caterpillars feed on dicots and concentrate on members of the Legume/Pea family (adults nectar on wildflowers). DNA analysis supports the separation.
The Dicot skippers are described as having rather triangular wings. They perch with wings partly open, with wings over their backs in typical butterfly fashion, or with the front wings more “up” and hind wings more out to the sides, like some of their smaller Grass skipper brethren.
NCs are found from coast to coast, and both north and south of the borders in the same kinds of shrubby/open/edge habitats that the JD enjoys. They are a dark, plain skipper about the same size as the JD; their caterpillar is drab: http://bugguide.net/node/view/35103/bgimage/.
Male NCs watch for females from perches on twigs or on the ground, and they chase rival males. Wagner says that an egg-laying female has a “distinctive, fluttering flight, with frequent touchdowns to ‘taste’ foliage of possible food plants with their feet and genitalia.” She’s looking for hog peanut, tick-trefoil, or bush clover. Caterpillars sate themselves on the leaves of their host plants during summer and then create a leafy winter shelter. After their “sleeping bag” drops off of its plant, the caterpillar spends the winter on the ground among the fallen vegetation.
NCs were listed as injurious insects in a 1797 publication on the insects of Georgia (although at that time they were considered a variety of the Southern Cloudywing). It seems that populations of the very adaptable NC increased as they discovered agricultural legumes, and the caterpillars added alfalfa and red clover to their menu. Check out the list of host-plant-switchers at http://www.butterfliesofmassachusetts.net/history.htm.
Thanks for the IDs, Mike.