Life Histories of Cascadia Butterflies

Checkerspots and Crescents

266 life histories of cascadia butterflies Checkerspots and crescents are represented in Cascadia by 10 species in 3 genera. They are medium-sized orange and black butterflies found in habitats ranging from low shrub-steppe and coastal lowlands to alpine meadows. Males and females are similar in most species, and males eclose a week or so before females. Some species are widespread and can be abundant (Euphydryas spp.) while others are uncommon and localized (e.g., Phyciodes pallida). All nectar readily on flowers, and males are often seen in mudding congregations. Eggs are laid in close-packed masses of 10–300, usually on the undersides of leaves. The rounded barrel-shaped green or yellow eggs are shiny with subtle vertical ridges. The spiny larvae are dark with bright yellow or orange aposematic markings when mature but drab gray/black in early instars, living in messy silk communal nests for protection. Mature larvae are solitary, coiling and falling to the ground if disturbed. There are usually 5 instars, but larvae may go through additional instars if there is more than 1 diapause. Pupae hang and are either tan-gray or white with black and orange markings. The Mylitta Crescent is multibrooded and the Northern Crescent may have 2 generations, but all other species have a single annual generation. Larval hosts include asters (Compositae), figworts (Scrophulariaceae), and plantains (Plantaginaceae). Chlosyne checkerspots use only asters or rabbitbrush, while crescents use asters or thistles. Euphydryas checkerspots use a variety of figworts, including penstemon, paintbrush, snowberry, honeysuckle, and monkeyflower, as well as plantains. Many of these hosts contain iridoid alkaloids that are sequestered by aposematic larvae, making them unpalatable to vertebrate predators. Overwintering occurs as partly grown larvae, often in communal nests, and some species remain partially active, feeding opportunistically as conditions permit. Some species are able to reenter diapause if spring conditions are unfavorable, extending life spans to 2–3 years. Postdiapause larvae sometimes switch host plants and spend much time basking in sunshine to hasten development. Family Nymphalidae Subfamily Nymphalinae (part) checkerspots and crescents c 267 subfamily nymphalinae (part) | family nymphalidae checkerspots and crescents 268 life histories of cascadia butterflies Hoffmann’s Checkerspot Chlosyne hoffmanni (Behr) Adult Biology Chlosyne hoffmanni ranges in a narrow band along the Cascades from S BC to OR. Beyond Cascadia the range extends into central CA in a narrow band along the Sierra Mts. The single flight is early May– mid-Aug. In Cascadia C. hoffmanni is found from 1,000 to 7,000 ft (Pyle, 2002; Warren, 2005), although most populations occur below 4,000 ft. Larval hosts are asters, including Eucephalus ledophyllus (Cascades Aster), Eurybia conspicua (Showy Aster), and probably others; Scott (1986a) reported that Eucephalus breweri (Brewer’s Aster) is used in CA. It is a montane butterfly, preferring mountain meadows, logging roadsides, riparian zones, and seeps. Males frequently mud-puddle at wet spots along unpaved roads or along stream margins, often in the company of blues and Euphydryas spp. Both sexes visit flowers, and males patrol corridors in search of mates. After mating, typically in July, females lay large masses of eggs on the undersides of aster leaves, usually at midheight on the host, with a preference for plants in partial shade. Eggs are placed in neat rows crowded together. We found egg masses of 82 and 108 eggs; Newcomer (1967) determined that masses averaged 72 eggs (range 25–179) in 12 masses found in Bear Canyon, Yakima Co., WA. A female observed in Reecer Canyon., Kittitas Co., WA, took ~20 min to oviposit on a small aster, body inverted and with outspread wings; Newcomer (1967) observed a female lay a mass of 82 eggs in 7 min. Immature Stage Biology Wepartiallyrearedthisspecies10timesfromcollected eggs or larvae. On July 7 and July 12 eggs were collected at Reecer Canyon, and on Aug 4 and Aug 11, L2 were collected at the same locality (all different years). Overwintered larvae were collected 6 times between June 2 and June 10 (different years) at Liberty, Kittitas Co., and on Aug 28 more than 100 nests with diapausing larvae were found at Reecer Canyon. In several cases the larvae were reared through to adults. Eggs hatched 11–16 days post oviposition at 20–22 °C. Development from L1 to L3 took ~16 days, after which the larvae ceased growing but continued feeding, then entered diapause. Postdiapause development from L3 to pupation took ~14 days, and adults eclosed ~15...