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Sunday, May 17, 2015

Duskywing Butterflies – the genus Erynnis


Funereal Duskywing butterfly (Erynnis funeralis ) in Mother Nature's Backyard

Despite the drought, it’s shaping up as a good year for butterflies in local gardens.  This may be due in part to difficult conditions in the wilds; many larval food plants (and water) are unavailable.  We’ve spoken before about the importance of native plant gardens when times get tough: http://mother-natures-backyard.blogspot.com/2014/11/maintaining-your-new-california-garden_15.html

In Mother Nature’s Backyard, we’ve already seen a first wave of the smaller butterflies known collectively as ‘Skippers’ (family Hesperiidae).  The Skippers are somewhat different in appearance and separated from other common butterflies in terms of their evolution.  While many local Skippers are yellow-orange and black (or white and black), one group is notable for its dark color and medium size.  These are the Duskywing butterflies, grouped in the genus Erynnis.  If you’ve seen a very dark 1 ½ inch (4 cm) butterfly flitting through your garden it’s likely a Duskywing.

The Duskywings are classified as spread-wing Skippers, a group that’s typically dark brown in color. Its members hold both sets of wings open when perching, while other Skippers perch with wings closed.  The genus Erynnis contains a number of species, 17 of which are native to N. America.   Duskywing species are quite similar in appearance, making them very difficult to tell apart, even from a good photograph.   The most accurate way to determine the species is by examining differences in their sexual organs under the microscope.

Six Duskywing species are known to inhabit Los Angeles County (see below); most are found only in the wilds, where their larval food plants are common.   Of the six, the Funereal Duskywing (Erynnis funeralis) is by far the most likely to visit local gardens; another possible candidate is the Mournful Duskywing (Erynnis tristis) and possibly the Afranius Duskywing (Erynnis afranius).
 

Name
Distinguishing characteristics
Adult food
Larval food
Afranius Duskywing  Erynnis afranius
Hindwing fringe pale tips
Upper side medium brown
Upper wing white spotted
Males perch in swales, gullies; wild lands
Flower nectar
Legumes including: deervetch (Acmispon glaber/Lotus scoparius), Lupine (Lupinus spp), Milkvetch (Astragalus spp), Spanish Clover (Lotus purshianus), Thermopsis
Sleepy Duskywing
Erynnis brizo
 
 
Upper forewing black-brown; blue-brown spots. Hindwing brown with lighter brown spots
Oak-pine, forest edges
Flower nectar: blueberry, dandelion,  violets, strawberries
Native Quercus including: Quercus dumosa ;  other Quercus spp.
Funereal Duskywing Erynnis funeralis
Forewing narrow, pointed
Upper side dark brown-gray
White fringe, hind wing
Local gardens
Flower nectar: California buckwheat; Black sage; Stachys spp.
Legumes including: Acmispon glaber/Lotus scoparius, Medicago species, Olneya tesota. alfalfa and vetch (Vicia)
'Californian' Pacuvius Duskywing, Erynnis pacuvius callidus
Milky white spots, upper wing of males
Hooked antennae
Flower nectar
Ceanothus species
Western Oak Duskywing, Erynnis propertius 
Larger size
Brown hindwing fringe
Hilltopping; puddling
Wild lands (foothills)
Flower nectar
Native Quercus including: Quercus agrifolia
Mournful Duskywing Erynnis tristis
White fringe, hindwing
 
Mostly wild lands
Flower nectar: mints, Salvia spp., lavenders, Verbena, garden flowers
Quercus including: Quercus agrifolia, Q. lobata,  Q. douglasii, non-native oaks

 
The species range for local Duskywings is largely limited by their larval food plants.   Three of the six require native oaks (Quercus species) for breeding, including the Mournful Duskywing.  If you live in an area with oaks, Mournfuls may visit your garden.   The Pacuvious Duskywing requires Ceanothus species – in greater abundance than found in most gardens.  The Afranius and Funereal Duskywings utilize a number of native and non-native legume species, making them the best candidates as garden visitors.


Funereal Duskywing (Erynnis funeralis) in flight


Funereal Duskywings are difficult to photograph.  They are rapid, erratic flyers, moving from flower to flower surprisingly quickly.  We’ve had our best luck capturing them nectaring on Black Sage (Salvia mellifera).  Be patient and use a telephoto lens; they sometimes rest with wings outstretched (cool days) or closed (in hot sun). 

The Funereal Duskywing is a small-medium butterfly 1 ½ to 1 ¾ inches (3.4 - 4.5 cm) wide.   It ranges from Southern California, Arizona, New Mexico and Texas south to Argentina and Chile, although it sometimes strays further north.   Several characteristics differentiate it from other local Duskywings: 1) its forewing is narrow and pointed, while its hindwing is triangular; 2) the hindwings have a distinctive white fringe, visible on both the upper and lower sides of the wing (clearly visible whether the wings are open or closed – even in flight).  Only one other local Duskywing – the Mournful – has white wing fringes.
 
Funereal Duskywing (Erynnis funeralis) - front (upper) side

While the overall color of Erynnis funeralis is dark brown, the coloration is more complex and varied than you might expect.  As seen above, the front side of the forewing is marked with subtle blotches of gray and lighter brown. The patterns on the forewing extend almost to the edge of the wing and there is a larger, pale splotch (in ours a ring) near the top.  The hindwing has a overall coppery cast, in addition to the distinctive white fringe.
 
Funereal Duskywing (Erynnis funeralis) - back side

While the adults utilize a range of flowers, they seem particularly fond of Black sage (Salvia mellifera) in our gardens; we’ve also seen them nectaring on the Woodmints (Stachys species) and other plants in the Mint family.  Adults are known to ‘puddle’ (sip moisture and minerals from mud or moist sand), although we’ve not observed this (our garden is likely too dry).

Funereal Duskywings have three broods a year, during warm weather from March to December.  In our area they typically fly from February or early March to early May (first generation),  mid-May to late June or July (second generation) and late summer to October or November (third generation).  We often see an uptick in numbers in March and again in June/July.   

The single, yellow eggs are deposited on the leaves of the host plant.  Host plants are a range of legumes (family Fabaceae) including Deervetch (Acmispon glaber/Lotus scoparius), Medicago species (alfalfa; Bur-clovers), Olneya tesota (Desert ironwood) and vetch (Vicia species)  Larvae are pale, translucent green with faint lines and a dark gray head.  Caterpillars eat the leaves and form simple shelters of rolled leaves.   It takes about 35 days to progress from egg to adult.

For more pictures and information on Funereal Duskywings see:


 

If you live near oak trees, you may also see the Mournful Duskywing (Erynnis tristis).   This is our second ‘white fringed’ species; it can be distinguished from Erynnis funeralis by a row of long white spots near the margin of the underside of the hindwing.  This species flies at the same time as the Funereal Duskywing, with three broods a year.  It nectars on a wide range of native and non-native plants including Verbenas, Yerba Santa (Eriodictyon species), California Buckeye (Aesculus californica), native buckwheats (Eriogonum species), Milkweeds and other garden flowers, especially the Butterfly Bush (Buddleia davidii).  Larval foods include Coast liveoak (Quercus agrifolia) and other native and non-native oaks. 

For more on the Mournful Duskywing see:


 

The Afranius Duskywing (Erynnis afranius) is slightly smaller than Erynnis funeralis and has pale-tipped wing fringes, rather than white.  Like the Funeral Duskywing, its larvae require legumes, including Deervetch (Acmispon glaber/Lotus scoparius), Lupines (Lupinus species), Spanish Clover (Lotus purshianus), the Goldbanners (Thermopsis species) and Milkvetch (Astragalus species).   We have not found records of this species in gardens, however its range, habitat and food requirements suggest it may do so.

For more on Afranius Duskywing see:



For pictures and information on the 'Californian' Pacuvius Duskywing (Erynnis pacuvius callidus) see:


 
For pictures and information on the Western Oak Duskywing (Erynnis propertius) see:


 

 

We encourage your comments below.   If you have questions about Duskywing butterflies or other gardening topics you can e-mail us at :  mothernaturesbackyard10@gmail.com

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