Wednesday, January 25, 2017

Moths and Butterflies of Southwestern Oregon (2016)

California Sister (Adelpha californica)
When I was a young kid, before my angst-ridden teenage years, I was always excited by the sight of a butterfly, and naturally, if I saw one I attempted to capture it (unsuccessfully, however). Being mostly harmless creatures (with the exception of the stinging hairs of some caterpillars and adult moths, and a few species of moths in the genus Calyptra with piercing mouthparts), and often large and brightly colored, it is no surprise that butterflies and some moths are some of the most adored of all insects, and perhaps of all pollinators. Usually this appreciation is directed towards the butterflies (Papilionoidea), though there are also many brightly colored moths that garner our attention. In any case, butterflies are representative of one of few groups of insects that aren't arbitrarily feared.
Mossy Swallow Moth (Feralia februalis)
Moths and butterflies make up the order Lepidoptera, which literally translates to scaled wing (from the ancient Greek λεπίς ‎(lepís, “scale”) and πτερόν ‎(pterón, “wing”). This name is in view of the fact that the wings of all lepidopterans are covered in many small scales that overlap. Many have scales of various colors that together form cohesive patterns. The patterns are sometimes brightly colored, either as warnings or perhaps as a means of attracting a mate, or they are dull and help them blend in with their environment to avoid being eaten. Most but not all butterflies feed on nectar as part of their diets, as do many moths, though there are some moths which do not eat as adults (some don't even have functional mouthparts or digestive systems) and are in the adult stage only long enough to mate.
Unidentified caterpillar on Arctostaphylos viscida, a host plant to many species of Lepidoptera.
One thing most lepidopterans have in common is the larvae are plant feeders, occasionally feeding on a specific group of plants or even only on a single species. While they are in this life stage they are vulnerable to attacks from predatory vertebrates like birds or by predatory wasps and other arthropods. Parasitoid wasps often use caterpillars as hosts for their offspring. Egg(s) of parasitoid wasps are laid nearby, on, or in the caterpillar by means of an ovipositor. The wasp larvae then burrow their way through the insides of the caterpillar, eating as they go, until they are ready to exit and pupate. Though I have not seen this, many gardeners have often encountered the tomato hornworm (Manduca spp.) with dozens of small white braconid wasp cocoons on its exterior. At that point, the caterpillar is greatly weakened and will likely be unable to pupate, then die. There are also hyperparasitoid wasps which parasitize the parasitoids already within a caterpillar, possibly saving the caterpillar from being eaten alive.
An adult caddisfly, Dicosmoecus sp. (Trichoptera)
Butterflies are believed to have evolved from moths over fifty million years ago, and the first butterfly fossils are from the Eocene. Moths have been around a lot longer, the earliest fossils date to at least 190 million years old. The earliest lepidopterans are thought to have evolved from caddisflies (order Trichoptera) which have membranous wings instead of scaled wings. There are around 165,000 estimated species of Lepidoptera in the world, ~13,700 of which are true butterflies while the rest are fairly considered moths.
Edwards' Glassy-wing Moth (Pseudohemihyalea edwardsii)
There are some general differences between moths and butterflies that can be observed by the average viewer. Here I will list several differences in no order of importance. Butterflies are entirely diurnal while moths have diurnal, nocturnal, and crepuscular (active during twilight) species. The antennae are probably the most telling feature, butterflies have thin filamentous antennae with clubbed ends (sometimes hooked as is the case with the skippers) while moths typically have antennae which end in a point in the case of females or feathered in the case of some males. However, some moths (i.e. ghost moths, Hepialidae) have very short antennae that aren't readily apparent at all.
A predator of moths, I observed on one foggy fall morning as Western Bluebirds (Sialia mexicana) stalked and chased large  hairy moths hiding in grassy tussocks in a field. Upon discovering the moths, the birds would pursue the moth. The moth would attempt to flee and its silhouette could be seen in the sky with several Western Bluebirds in close pursuit until its inevitable capture.
Wing color does little to help determine whether it is a moth or a butterfly, though the position of the wings at rest can be diagnostic. Most butterflies hold their wings flat together when they land while moths can either hold them to the sides, or wrapped against their bodies (as you'll see in photos below). Wing position isn't always reliably diagnostic, since there are exceptions in both moths and butterflies (i.e. Geometridae or Hesperiidae, respectively) which do not conform. Another key difference, though not readily apparent, is that while all butterflies eat as adults, many moths only eat in the larval stage and may not even have functional mouthparts or digestive systems as adults. This discounts many moths as pollinators, but they are still valuable as a food source to countless vertebrates such as songbirds and even bears.
Milkweeds are important host plants for many butterflies and moths. Asclepias cordifolia, or heartleaf milkweed, is native to California and Oregon and a host plant for monarchs (Danaus plexippus, Danainae).
Adults of many moths and caterpillars feed on nectar from flowers and are widely regarded as pollinators. However, many moths do not feed at all as adults, and of the species that do there are many other sources of nutrition that they utilize as adults. Some adults feed on honeydew or tree sap (i.e. the Mourning Cloak, Nymphalis antiopa, which prefers sap from oak trees). Many butterflies are attracted to rotting fruit and mud. Others, particularly males of both moths and butterflies, feed on fluids taken from feces or even carrion. Salts found in carrion, feces, and sweat are useful for the adult males, and usually not found in nectar. To read about creating habitat for moths and butterflies, I highly recommend the book Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects written by the Xerxes Society (Timber Press 2016). I wrote a review for Gardening for Butterflies for the Native Plant Society of Oregon, read it here.

I have compiled all the moths and butterflies I have photographed this year and arranged them in the only way that made sense to me: taxonomically (in other words, by scientific classification). This is not all the lepidopterans in my area, merely the ones I have both seen and had the opportunity to photograph. It may come as a surprise to some that butterflies and skippers are simply a branch of this classification, merely a specialized group of moth descendants. That being said, I have decided to place butterflies at the bottom of this report. If one is highly averted to moths for some reason, they may scroll to the bottom. I, however, think moths have a lot to be appreciated, from their intricate (if occasionally dull) patterns, to their obscure lifestyles, their importance in the food web is not fully understood and they may ultimately have more to offer than butterflies. Please, enjoy.

Superfamily Alucitoidea

Family Alucitidae

The many-plumed moths are named for their wings which are composed of feather-like rigid spines from which flexible plumes radiate. This gives them a characteristic appearance. Larvae feed on honeysuckle (i.e. Lonicera hispidula) and snowberry (i.e. Symphoricarpos hesperius), both of which are present in my area in Southwestern Oregon (Rogue Valley).
Alucita sp. (January)
Alucita spp. are small moths, with a wingspan of around one centimeter. Their host plants are snowberries (Symphoricarpos spp.) which are shrubs in the honeysuckle family, Caprifoliaceae. Symphoricarpos albus var. laevigatus and Symphoricarpos rotundifolius have been documented host plants, perhaps other species as well.

Superfamily Lasiocampoidea

Family Lasiocampidae

This family is best known for the tent caterpillars, Malacosoma californicum in the western US and M. americanum in the east. Tent caterpillars build protective webs in the limbs of their tree or shrub hosts, though they aren't the only moths to do so. The fall webworms, Hyphantria cunea (Erebidae), builds similar silken nests in summer and fall while tent caterpillars make their nests in spring. In either case, the gregarious caterpillars defoliate the area within their protective webbing. Other moths in the Lasiocampidae are solitary in the larval stage.

Subfamily Macromphaliinae

Tolype distincta (September)
Tolype distincta is native to coniferous forests in the Pacific Northwest. Caterpillars feed on various conifers such as madrone (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), and other Pinaceae, as well as having been documented on non-coniferous trees and shrubs bigpod ceanothus (Ceanothus megacarpus), mountain mahogany (Cercocarpus betuloides), and canyon live oak (Quercus chrysolepis). Adults are nocturnal and active in late summer and fall. They are drawn to lights, the individual in my photo was under a porch light the following day trying unsuccessfully to blend in with the cedar siding.

Superfamily Noctuoidea

Family Erebidae

The Erebidae, whose name has roots in Greek and Latin meaning "darkness" or "evening" reflecting when they are active, are a group of often colorful moths. This group contains some interesting members including the piercing moths (Scoliopteryginae pierce fruit to imbibe the juice, Calpinae pierce fruit for the juice as well as the skin of some mammals to feed on blood). Some members of the Erebidae have even been proven to make a sound used to deter or confuse bats, one of their primary predators. The bright colors and patterns of some species are thought to deter sight based predators such as birds, a signal that they may be toxic or distasteful.

Subfamily Arctiinae

Pseudohemihyalea edwardsii (September)
A large nocturnal moth, I found Pseudohemihyalea edwardsii clinging to a door under a porch light. The moth was nearly two inches in length, and quite conspicuous. I hope for the sake of the moth that this species is toxic since it was so highly visible. Where does this creature hide? Perhaps it is adapted to the crevices of the bark of their hosts, the oaks. Perhaps it is better hidden in the filtered light of the canopy of an oak than a blue door.
Pseudohemihyalea edwardsii has translucent wings which give it the name Edwards' Glassy-wing (September)
Pseudohemihyalea edwardsii appears to host exclusively on oak trees. Documented hosts include the species coast live oak (Quercus agrifolia), canyon live oak (Quercus chrysolepis), valley oak (Quercus lobata), and I would expect other species of oak as well within their range. P. edwardsii is found from Washington, through Oregon and California, and Arizona.

Family Noctuidae

Owlet moths, cutworms, and armyworms are the common of this large family. Owlet moth refers to the hairy bodies of some species which are reminiscent of baby owls. Cutworm or armyworm refers to the voracious and destructive appetites of some species which have sometimes been considered serious agricultural threats. Most are nocturnal and are attracted to lights, except the subfamily Agaristinae which are day flying.

Subfamily Amphipyrinae

Feralia februalis (February)
Known as mossy swallows, the genus Feralia is native to much of the United States. Feralia februalis is found from late winter to early spring in mixed coniferous woodlands in the Pacific Northwest, often in association with oaks. Their primary host plant is Oregon white oak (Quercus garryana) in Oregon, though they have also been documented on blue oak (Q. douglasii). In California they have been reported to use other plants as hosts such as California buckeye (Aesculus californica), readheart mountain lilac (Ceanothus spinosus), mountain mahogany (Cercocarpus betuloides), hollyleaf cherry (Prunus ilicifolia), and blue elderberry (Sambucus nigra ssp. caerulea). At least two other species of Feralia are native to Oregon, F. comstocki and F. deceptiva, which feed exclusively on Douglas-fir, Pseudotsuga menziesii.
Feralia februalis (February, of course!)
It is not known whether this species, or any species in the genus Feralia for that matter, feeds on nectar or feeds at all as an adult. Unlike butterflies, as previously stated, there are moths which do not feed as adults but there is a large deficiency of knowledge about which moths do or do not feed as adults.

Subfamily Noctuinae

Feltia jaculifera, attracted to lights at night, yet are active both day and night. (September)
Cutworms are considered pests by both gardeners and farmers alike. Envision a beaver gnawing away at the base of a tree and you may understand their method of feeding. Larvae are usually active on or in the soil, often emerging at night to feed and hiding during the day. Feltia jaculifera feeds on a wide variety of plant hosts, many native to its range and a few non natives of agricultural importance. The closely related F. subterranea, however, is a pest of a dozen or more plants of agricultural importance including beets, carrots, asparagus, peas, potatoes, and corn among others.
Feltia jaculifera (September)
Feltia jaculifera feeds on nectar as an adult, and may very well provide beneficial pollination services. This species has been observed feeding primarily on plants in the Asteraceae, including Joe Pye weed (Eutrochium purpureum), green-headed coneflower (Rudbeckia laciniata), nodding beggarticks (Bidens cernua), smooth beggarticks (B. laevis), and Canada goldenrod (Solidago elongata), although there are surely others of importance to this species as nectar plants. Various solitary ichneumon wasps are documented as using various species of Feltia as hosts, namely Ceratogastra ornataCampoletis flavicincta, Enicospilus merdarius, and Spilichneumon superbus.

Subfamily Plusiinae

Autographa californica nectaring on a zinnia (October)
The genus Autographa is represented in the West by a handful of species. Some of which have seemingly limited preferences of host plants, while A. ampla and A. californica utilize many species of plants in many families as hosts. Host plants in the families Asteraceae, Fabaceae, Lamiaceae seem to be most commonly used. Trees are also often used as hosts, namely alders (Alnus spp.) and willows (Salix spp.), but also balsam poplar (Populus balsamifera), quaking aspen (P. tremuloides), birch (Betula papyrifera), chokecherry (Prunus virginiana), and viburnum (Viburnum spp.).
Autographa californica with wing damage, possibly from a bird or another predator. (October)
Autographica californica is a common species often regarded as a pest. Caterpillars of this species are known to feed on a wide variety of agriculturally important crops, though they are also abundant in woodlands and forests. Adults are mostly nocturnal, but may come out in the day to feed on nectar. The aren't picky about where their nectar comes from, and may in fact contribute to the pollination of some plants. A. californica is one of few pollinators to be documented visiting Triteleia laxa, a bulb native to California and Oregon. The braconid wasp Meteorus autographae uses Autographa spp. as hosts in the Eastern US. 

Superfamily Pterophoroidea

Family Pterophoridae

The plume moths are closely related to the Alucitoidea, or many-plumed moths. Both have wings that apparently lack scales, but are rather adorned with feather-like plumes. The easiest way to differentiate between the two is how they hold their wings when they land. Many-plumed moths hold their plumes out like a fan, while pterophorid moths make a distinct "T" shape. Both are nocturnal, but may be found clinging to walls during the day. There are rumors that plume moths bite, and although it has never been substantiated there is a chance possibility that some have proboscises capable of piercing human skin (most likely male moths, but this is purely non-expert conjecture).
Pterophorid moth investigating a daffodil (March)
Plume moths visit a wide range of plants to use as hosts, the vast majority are in the Asteraceae, or sunflower family. They have also been documented using hosts in other families, such as California horkelia (Horkelia californica: Rosaceae), twinberry honeysuckle (Lonicera involucrataCaprifoliaceae), and coyote mint (Monardella villosa: Lamiaceae). They also feed on nectar as adults. For three years I have observed pterophorids meticulously visiting the florets of Muscari spp., or grape hyacinths, in the spring at night. They have also been documented visiting yarrow (Achillea millefolium: Asteraceae), which happens to be one of their host plants.

Superfamily Sesioidea

Family Sesiidae

Sesiid moths are known as clearwing moths because most species have wings that are clear. Most are thin and somewhat small, with white, red, or yellow stripes on a black body. Many are likely wasp mimics, a strategy that may reduce predation and allows them to be active during the day. Some resemble yellowjackets (Vespula spp.) while others resemble other types of wasps. Sesiid moths in the genus Alcathoe have black bodies with orange wings, very similar in appearance to the large tarantula hawk wasps (Pepsis spp.) which share similar distributions in the American Southwest. Larvae feed within either woody plants or within roots, and some are considered serious pests.

Subfamily Sesiinae

Penstemonia clarkei (Inset: a male yellowjacket, Vespula pensylvanica)
Penstemonia clarkei is a small moth which, as the generic epithet suggests, seeks hosts in the plant genus Penstemon or the related KeckiellaPenstemonia larvae feed within the crown of their hosts, often to the detriment of the host. Penstemonia spp. are wasp mimics (compare to the inset image of a male Western yellowjacket, Vespula pensylvanica).

Superfamily Geometroidea

Family Geometridae

Geometrid moths are so named for the mode of locomotion of their caterpillars, also known as inchworms or loopers. "Geometridae" derives from the Greek word γεωμέτρης (geometer, or earth-measurer). Most caterpillars feed on plant foliage, and adults are typically but not always nocturnal. Adults are attracted to lights.

Subfamily Ennominae

Cochisea sinuaria (September)
Although dull in color, Cochisea sinuaria is rich in pattern. I found this specimen clung to the wall of an outbuilding under a light, but I imagine against the bark of a tree it would be nearly indistinguishable. C. sinuaria larvae feed primarily on the leaves of manzanita, particularly Arctostaphylos viscida and A. glauca. The species also has been associated with other potential host plants deerbrush (Ceanothus integerrimus), coastal sage scrub oak (Quercus dumosa), mountain mahogany (Cercocarpus betuloides), and laurel sumac (Malosma laurina).

Tetracis jubararia (October)
Tetracis jubararia is a twig mimic as a caterpillar. Adults are active in late summer and fall, when they lay eggs and perish. Eggs endure winter, and hatch the following year. T. jubararia has many hosts, usually broadleaf trees, but also many shrubs. A few of the host genera include maples (Acer spp.), alders (Alnus spp.), birches (Betula spp.), dogwood (Cornus spp.), cottonwood (Populus spp.), currants (Ribes spp.), azaleas (Rhododendron spp.), willows (Salix spp.), elderberry (Sambucus spp.), snowberry (Symphoricarpos spp.), and huckleberries (Vaccinium spp.) among many others.

Subfamily Geometrinae

Nemoria darwiniata (September)
The small Nemoria darwiniata are common in wet or dry woodlands in much of North America. I found this one in an apiary while working some hives, hence the sugar-coated glove (the moth was on my finger).
Nemoria darwiniata (September)
Nemoria darwiniata has many hosts, usually broadleaf trees and shrubs. Hosts include madrone (Arbutus menziesii), manzanita (Arctostaphylos spp.), wild lilac (Ceanothus spp.), golden chinquapin (Chrysolepis chrysophylla), yellow rabbitbrush (Chrysothamnus viscidiflorus), oceanspray (Holodiscus discolor), California wax myrtle (Morella californica), bitterbrush (Purshia tridentata), oaks (Quercus spp.), and willows (Salix spp.) As the caterpillar feeds, it takes on the color of the host plant, which is common for many moths as a defensive strategy.

Subfamily Larentiinae

Costaconvexa centrostrigaria (October)
The Bent-line carpet moth, Costaconvexa centrostrigaria, is a small American species, in fact the only species of Costaconvexa in the US, although it is widespread. Adults fly from May to October in the Northwest, but all year in the southern distribution of the species. Adults are also drawn to light, which is where I found this individual.
Costaconvexa centrostrigaria (October)
Larvae of Costaconvexa centrostrigaria feed exclusively on Polygonum species (knotweed) and also the closely related Persicaria hydropiper (formerly included in the genus Polygonum).

Superfamily Pyraloidea

Family Pyralidae

The family Pyralidae has some of the most diversity in life histories of all lepidopterans. Diets vary widely, from phytophagous species to species that live parasitically in ant nests (Wurthiinae spp.), predatory species (certain Phycitinae spp. prey on scale insects), or live in the nests of bees as inquilines or kleptoparasites. Some species spend their larval stage under water (Acentropinae) while others are adapted to very dry environments, such as living off of dried stored food products (some Phycitinae and Pyralinae) and are considered to be pests.

Subfamily Galleriinae

Galleria mellonella on wax comb of Apis mellifera
Galleria mellonella is better known as the greater wax moth, most often regarded as a pest of honey bee colonies. They are one of a handful of moths which live within apid bee nests, that is bees within the family Apidae which build wax comb (i.e. bumblebees, honeybees). Wax moths are also occasionally found within old vespid wasp nests. Both the greater and lesser wax moths (Galleria mellonella and Achroia grisella, respectively) are pests within honeybee colonies, as well as in the nests of stingless bees (Meliponini). Aphomia sociella is a pest of bumblebee nests in the UK and perhaps the Eastern US as an introduced species, only rarely a pest in honey bee colonies.
Galleria mellonella
The greater wax moth is not all bad, though the species does create a headache for beekeepers. The larvae serve as hosts for braconid and ichneumon wasps (Habrobracon hebetor and Pimpla turionellae, respectively, and perhaps others). Vespid wasps, such as yellowjackets and paper wasps (i.e. Vespula and Polistes spp., respectively) prey on the larvae of wax moths. The greater wax moth is also used in laboratories as infection models for the study of bacterial diseases and for antimicrobial drug testing. In this way they replace vertebrates, particularly rodents, which have presented many ethical issues as well as time and budgetary constraints. Few ethical restrictions keep researchers from running tests on wax moth larvae, and this may even incite some excitement from beekeepers who despise the moths.
Galleria mellonella larval silk and frass on honeybee comb
Greater wax moth females may lay over a thousand eggs in their brief adulthood, around twelve days. Adults are nocturnal, and probably attracted to the scent of beeswax. Many dozens of larvae may be found within a single frame tunneling below the surface of the comb. They build a protective layer of silk between frames, perhaps to allow easy passage from one comb to the next. The entire silken structure is laden with frass, or feces. In the wild the moths serve an interesting ecological role. When a wild or feral honey bee colony dies, the moths move in and destroy everything, leaving a nice clean cavity for new bees to move into rather than using the old comb which may be tainted with disease.
Galleria mellonella larval silk and frass
Typically the best defence against wax moths is to keep strong colonies. Populous and healthy honey bee hives will fight off any intruder. Stored comb is the most susceptible to wax moths. Cold temperatures are a good preventative measure as the moths require warmth to mate and lay eggs. Immature moths go through winter as either prepupae or perhaps as eggs if they are in protected locations. That said, certain strains of BT (Bacillus thuringiensis) are effective against wax moths.

Superfamily Papilionoidea

The superfamily Papilionoidea contains all of the butterflies, yet an alternative taxonomic treatment places the skippers (Hesperiidae) in a separate superfamily, Hesperioidea. Butterflies differ from the moths by a few key characteristics, and a number of other variable characteristics which can be used to support the key differences. Butterflies, unlike moths, have clubbed or hooked antennae, in other words the antennae end thicker than they began. Moths have antennae that taper to a point or are feathered in some males. Another key difference, moths have a frenulum, though not readily visible unless a moth is in hand, is a wing-coupling device that ensures the hind and forewings work in unison. Butterflies lack this feature. Other differences are variable, though may be accounted for together to make a positive identification. Butterflies are diurnal (occasionally crepuscular), yet moths are active both day and night depending on the species. Most butterflies are colorful, and most moths are dull colored. However, there are many drab butterflies and many colorful moths (particularly tropical moths). In the pupal stage, moths and butterflies differ in that moths tend to build silken cocoons while butterflies tend to build a chrysalis, often smooth with a hardened surface. This, of course, is variable as some moths also have pupal cases that are smooth and shell-like.

Family Lycaenidae

The family Lycaenidae, which means "little butterflies" due to the small size of many species, are widespread yet contain many rare and uncommon species. Known as the hairstreaks, blues, and coppers, they often have delicate wing markings. While many species are phytophagous, there are also predatory and parasitic species. Many species have mutualistic relationships with ants, where in exchange for protection by the ants the caterpillar secretes a complex sugary substance. Some of these caterpillars move directly into the ant mound where they continue to excrete the sugary substance sought by the ants. These caterpillars within the ants nest often become parasitoids and feed on the ants within the nest! Other lycaenids switch from a plant based diet to a predatory diet of aphids being tended by ants. Lycaenids often pupate underground, often within an ant colony, and they must emerge from the mound to fully expand and dry their new wings once reaching adulthood.

Subfamily Theclinae

Strymon melinus (June)
The gray hairstreak is a very common and widespread butterfly, and one of the most encountered of the hairstreaks. Their abundance may be due in part to their adaptability. They have a ridiculously wide range of host plants, and can be found nectaring on a similarly large array of plants. The caterpillars tend to take on the color of the host plant. They are occasionally considered pests as they have a preference for legumes, many agriculturally important. They are active from spring to fall, found in disturbed habitats, woodlands, and agriculturally dominated areas.
Mating flower longhorn beetles (Strophiona tigrina, upper left) and Strymon melinus (lower right)
Hosts vary widely from natives to nonnative plants, including garden plants and noxious weeds. In some areas they have even been shown to be dependant on exotic plants where native plants are uncommon, such as urban and suburban areas. Thus, an attempt to eradicate a neighborhood of all naturalized weeds may have a negative effect on the butterfly population. This suggests the need for programs to reintroduce native plants into urban and suburban areas, which will support a greater diversity of native pollinators.
Strymon melinus (upper left) and Bombus vandykei (lower right) on Allium ampeloprasum var. ampeloprasum (July)
Gray hairstreaks aren't picky about nectar, and will visit a wide array of plants for it. I personally have observed them visiting ornamental onions (Allium spp.) and wild buckwheat (Eriogonum spp.), though they have been documented visiting a wide range of flowering plants, many with easily accessible nectar.

Family Hesperiidae

The skippers, occasionally placed in their own superfamily (Hesperioidea), are typically small and short-bodied, hairy butterflies with a rapid skipping flight pattern. Many skippers are understandably confused for moths, their compact and hairy forms coupled with the position many of the skippers hold their wings. Many skippers hold their wings differently than most butterflies, instead of holding them flat together or in a flat plane many skippers hold their wings in a "V" shape. Many skippers are also comparatively plain in color, yet they still have the clubbed antennae similar to other butterflies, except skippers have a little pointed hook at the tip as well. Many skippers lay their eggs by dropping them on/near their host plant(s) one egg at a time, doing many passes to lay a sufficient number of eggs.

Subfamily Hesperiinae

Ochlodes sylvanoides (September)
The woodland skipper is a grass skipper native to the Western US as far east as North Dakota and north from British Columbia to Saskatchewan. They are primarily active in late summer and fall, during which time they imbibe nectar, find mates, and lay eggs, all in a matter of weeks. First instar caterpillars hibernate through winter, complete their feeding in the following spring, go through summer in diapause, then build their chrysalis and pupate to emerge as adults in the fall. They seek nectar from a  variety of plants, and males occasionally feed on carrion.
Ochlodes sylvanoides (September)
Grass skippers (Hesperiinae) use host plants in the grass family (Poaceae). The woodland skipper uses a variety of grasses and related plants as hosts, from Bermuda grass (Cynodon dactylon), canary grass (Phalaris spp., including the invasive P. arundinacea, but also Western natives P. californica and P. lemmoni), Colonial bentgrass (Agrostis capillaris), Johnson grass (Sorghum halepense), wildrye (Elymus cinereus, E. condensatus, E. trachycaulus ssp. trachycaulus, and E. triticoides), and wheatgrass (Agropyron sp.). The fact that some of these species are nonnative, even noxious, in Oregon and California speaks to the adaptivity of some butterflies due to their ability to utilize hosts they didn't coevolve with.
Ochlodes sylvanoides (September)
In 2016 I observed many woodland skippers nectaring on a pungent mint-relative, Trichostemma lanceolatum also known as vinegar weed (though the smell is more akin to gasolene). The plants are traditionally considered to be bee pollinated, yet I observed pollen being deposited consistently onto the top of the thorax of the skippers. Pollination seemed a likely scenario, though I can not confirm this with seed viability (I did not check).
Hesperia juba (October)
Another common skipper, the juba skipper is a relatively large skipper with a green body. They are typically a montane species but will move to lower altitudes. Females lay eggs singly, and caterpillars fold leaves together with silk to protect themselves. Caterpillars probably hibernate through winter, and may even develop under snow. They visit a huge variety of plants for nectar, the most frequently observed skipper in my area. Known hosts include bluegrass (Poa pratensis et al), bromes (Bromus inermis, B. rubens, and B. carinatus), Nevada needlegrass (Stipa nevadensis), reed canary grass (Phalaris arundinacea), slender hairgrass (Deschampsia elongata), and Tridens spp.

Family Pieridae

The whites, sulphers, and yellows comprise the family Pieridae. Unsurprisingly, they come in the colors white, yellow, orange, and occasionally black and many have ultraviolet markings used in courtship. They are mostly native to the tropics though there around sixty species native to North America. Some are introduced pests of plants in the cabbage family (cabbage, mustard, etc.) and legumes.

Subfamily Pierinae

Pieris rapae (October)
The cabbage white, Pieris rapae, is an introduced species. Caterpillars are very common pests of mustard family plants in spring and summer. Adults are common from spring to fall, widely distributed throughout the US but mostly found in agricultural and urban areas. They seek nectar on a variety of plants, both native and exotic. Caterpillars of P. rapea and the related P. brassicae are parasitized by the braconid wasp Cotesia glomerata.

Family Nymphalidae

The brush-footed butterflies are so named because their front two legs are much reduced in size and have small brushes that may be used to enhance their ability to smell or taste. In appearance they have only four legs because they use only four legs to walk, the two front legs are kept tight against their bodies when not in use. While many feed on flower nectar, many other feed mostly or solely on tree sap, rotting fruit, dung, or carrion. Brushfoots overwinter as adults or sometimes as larvae.

Subfamily Limenitidinae

Adelpha californica (syn. A. bredowii) taking up sweat from my finger (October)
The California Sister (Adelpha californica) is found in montane forests and oak woodlands from Western Oregon to Southern California. Caterpillars are common in late spring, when they feed on oaks (Quercus spp.), tanoak (Notholithocarpus densiflorus), and western chinquapin (Chrysolepis chrysophylla), all of which in the Fagaceae.
Adelpha californica (October)
The California Sister feeds mostly on honeydew and tree sap, though they occasionally take nectar from milkweeds, plants in the Asteraceae, or a variety of others. On the day I photographed this butterfly, it was attracted to the top bars of the frames in an empty beehive. The sweet smell of the propolis or other honeybee residues may have offered the butterfly a foodsource. Propolis, after all, is made from tree sap and plant resins.
Adelpha californica (October)
With some patience, and by moving very slowly, I had coaxed this butterfly to climb onto my finger. There it remained for over ten minutes, continuously probing my finger with its propolis. I had been working that day, so it may have been lapping up sweat. Aside from sap and honeydew, the California Sister will occasionally feed on sweat or animal scat, a source of salts and other minerals not found in sap, nectar, or honeydew.

Subfamily Nymphalinae

Junonia coenia with a damaged wing (September)
The common buckeye is common in most of the United States and eastern Canada, but in the West it is only found as far north as Oregon. They use a variety of host plants in a handful of families. Most of their host plants are in the Plantaginaceae (Antirrhinum, Gambelia speciosa, Hippuris vulgaris, Maurandya antirrhiniflora, Penstemon, Plantago, Veronica, and Kickxia spp.) and Scrophulariaceae (Cordylanthus rigidus subsp. rigidus, Keckiella, Nuttallanthus texanus, Scrophularia californica, and Linaria spp.), though they have also been known to utilize paintbrush (Castilleja spp., Orobanchaceae), monkeyflower (Mimulus spp., Phrymaceae) and western vervain (Verbena lasiostachys, Verbenaceae). They aren't strong fliers, but I had observed on more than one occasion that the common butterfly was more skittish than others.
Junonia coenia (October)
Peculiarly, common buckeyes have been documented by many observers as visiting various grasses and probing them with their proboscis as if they are attaining something from them. Poaceae do not produce nectar, being purely wind pollinated, so it is a mystery. The grasses yellow bluestem (Bothriochloa ischaemum var. songarica), spear grass (Heteropogon contortus), and dallisgrass (Paspalum dilatatum) have been documented as species visited by the buckeye. Two possibilities seem plausible to me, the first being that there are sap sucking insects leaving behind honeydew, and the second being that the grass sap had been exposed somehow (like a broken stem). Yet, a mystery it remains.

Further Reading

The Xerxes Society. Gardening for butterflies: how you can attract and protect beautiful, beneficial insects. Portland, OR: Timber Press, 2016. Print.
Caldwell, Jeffrey Allen. "California Plants as Resources for Lepidoptera: a guide for gardeners, restorationists and naturalists." (2016)
Carlson, Robert W. "Database of Hymenoptera in America north of Mexico: Ichneumonidae." Discover Life (2009) 
Coleman, R. A.; Barker, A. M.; Fenner, M. (1999). "Parasitism of the herbivore Pieris brassicae L. (Lep., Pieridae) by Cotesia glomerata L. (Hym., Braconidae) does not benefit the host plant by reduction of herbivory". Journal of Applied Entomology. 123 (3): 177-7. 

Er, Aylin, Fevzi Uçkan, David B. Rivers, Ekrem Ergin, and Olga Sak. "Effects of Parasitization and Envenomation by the Endoparasitic Wasp Pimpla turionellae (Hymenoptera: Ichneumonidae) on Hemocyte Numbers, Morphology, and Viability of Its Host Galleria mellonella (Lepidoptera: Pyralidae)." Annals of the Entomological Society of America 103.2 (2010): 273-82. Web. 

Dowdy, Nicolas J., and William E. Conner. "Acoustic Aposematism and Evasive Action in Select Chemically Defended Arctiine (Lepidoptera: Erebidae) Species: Nonchalant or Not?" Plos One 11.4 (2016): n. pag. Web. 

Er, Aylin, Fevzi Uçkan, David B. Rivers, Ekrem Ergin, and Olga Sak. "Effects of Parasitization and Envenomation by the Endoparasitic Wasp Pimpla turionellae (Hymenoptera: Ichneumonidae) on Hemocyte Numbers, Morphology, and Viability of Its Host Galleria mellonella (Lepidoptera: Pyralidae)." Annals of the Entomological Society of America 103.2 (2010): 273-82. 

French, Steven P., Marilynn G. French, and Richard R. Knight. "Grizzly Bear Use of Army Cutworm Moths in the Yellowstone Ecosystem." Bears: Their Biology and Management 9 (1994): 389.
Graves, Sherri D., and Arthur M. Shapiro. "Exotics as host plants of the California butterfly fauna." Biological Conservation 110.3 (2003): 413-33. 

Grehan, John. "Hepialidae." Hepialidae (ghost moths) and other Exoporia of the world. 

James, Windmill. "Ultra high frequency hearing in a moth." Frontiers in Behavioral Neuroscience 6 (2012): n. pag. Web.Miller, Jeffrey C., and Paul C. Hammond. "Lepidoptera of the Pacific Northwest." USDA Forest Service, n.d. Web. 

Karowe, D. N.; Schoonhoven, L. M. (1992). "Interactions among three trophic levels: The influence of host plant on performance of Pieris brassicae and its parasitoid, Cotesia glomerata". Entomologia Experimentalis et Applicata. 62 (3): 241–51. 

Kryukova, Natalia A., Ekaterina A. Chertkova, Alexandra D. Semenova, Yuri I. Glazachev, Irina A. Slepneva, and Victor V. Glupov. "Venom from the Ectoparasitic Wasp Habrobracon hebetor Activates Calcium-Dependant Degradation of Galleria mellonella Larval Hemocytes." Archives of Insect Biochemistry and Physiology 90.3 (2015): 117-30. 

Miller, Jeffrey C., and Paul C. Hammond. "Lepidoptera of the Pacific Northwest: Caterpillars and Adults." Forest Health Technology Enterprise Team: USDA (2003) 

Owen, T. "Lepidoptera of 2015." The Amateur Anthecologist. N.p., 20 Dec. 2015. 

Owen, T. "Trichostema lanceolatum." The Amateur Anthecologist. N.p., 4 Sept. 2016. 

Ramarao, Nalini, Christina Nielsen-Leroux, and Didier Lereclus. "The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis." Journal of Visualized Experiments 70 (2012): n. pag. Web. 

Shapiro, Arthur M. "The Californian urban butterfly fauna is dependent on alien plants." Diversity Distributions 8.1 (2002): 31-40. 

Sourakov, Andrei, and Everett Mitchell. "Meteorus autographae Muesebeck (Insecta: Hymenoptera: Braconidae)." Wasp Parasitoid. University of Florida, 2000. 

Tsai, Catherine Jia-Yun, Jacelyn Mei San Loh, and Thomas Proft. "Galleria mellonellainfection models for the study of bacterial diseases and for antimicrobial drug testing." Virulence 7.3 (2016): 214-29. Web.

Useful Websites

Eupithecia sp. caterpillar blending in with the reproductive organs of Crocus vernus