258 JOURNAL OF THE LEPIDOPTERISTS' SOCIETY Journal of the Lepidopterists' Society 33(4), 1979, 258 ERYNNIS BAPTISIAE (HESPERIIDAE) ON CROWN VETCH (LEGUMINOSAE) Crown vetch, Coronilla varia L., is a European perennial leguminous ground cover introduced to North America after 1890. It has been extensively planted by the Penn­ sylvania highway authorities to control embankment erosion. This program began in the mid-1930s and accelerated in the past 20 years (Wheeler, 1974, Can. Entomo!' 106: 897-908). Crown vetch is now thoroughly naturalized in Pennsylvania as a common component of old-field successional vegetation; it has also spread to adjacent south­ eastern New York and northern Maryland and Delaware. Wheeler (loc. cit.) conducted an insect survey of the plant and found two butterflies breeding on it (counties un­ specified): Colias eurytheme Bdv. (Pieridae) and Erynnis baptisiae (Forbes) (Hesper­ iidae). He did not consider either to be of potential economic importance. Shapiro (1966, Butterflies of the Delaware Valley, p. 53) judged E. baptisiae to be "locally common" in southeastern Pennsylvania but did not find it on Coronilla, al­ though C. eurytheme was recorded on that plant (p. 38). In 1966 and 1967 it was noted as singletons in the vicinity of Coronilla in Montgomery and Chester Counties. From 10-12 July 1978 I collected intensively in areas of Montgomery, Delaware, and Chester Counties, Pennsylvania which I had often visited from 1955 through 1966. In many of these localities I found E. baptisiae the commonest butterfly, a situation never previously observed. Where Coronilla was abundant E. baptisiae usually out­ numbered all other butterflies and skippers combined. Numerous ovipositions on crown vetch were observed, and, notably, male "territoriality"-which is very con­ spicuous in low-density populations of E. baptisiae-was much reduced or even ab­ sent. Thirty specimens were eullected in an hour at a 0.5 ha stand of the plant in Malle Township, Delaware Co. This unprecedented abundance may reflect an upward shift in the carrying capacity of the environment for E. baptisiae in the presence of a newly adopted, exotic host. A precisely parallel situation is believed to exist with populations of Pieris napi micro­ striata Comstock (Pieridae) on introduced watercress in California (Shapiro, 1975, J. Res. Lepid. 14: 158-168). Ongoing monitoring of the range and population levels of E. baptisiae where Coronilla occurs would be most desirable. ARTHUR M. SHAPIRO, Department of Zoology, University of California, Davis, Cal­ ifornia 95616. Journal of the Lepidopterists' Society 33(4), 1979, 258-260 DOES HESPERIA JUBA (HESPERIIDAE) HIBERNATE AS AN ADULT? The life history of Hesperia juba Scudder is very poorly known. The early stages were described by MacNeill (1964, Univ. Calif. Pub!. Entomo!. 35: 67-77), who ob­ served that "the adults are present from April through October, with some variation according to locality; evidently emergence is rather continuous and there are no distinct seasonal broods." This was inferred from the data on 769 specimens from hundreds of localities, not incorporating long series from single places. For southern California, Emmel and Emmel (1973, Butterflies of Southern California, p. 84) record two broods, April-June and August-September. This is closer to the pieture which emerges when VOLUME 33, NUMBER 4 259 long series from single localities in northern California are examined. Since 1972 reg­ ular, frequent butterfly sampling has been done in the Donner Pass vicinity (2,100 m), Nevada and Placer Counties, as part of a larger phenological study. During this period 525 individuals of H. juba have been examined. Emmel and Emmel (1962, J. Lepid. Soc. 16: 36) collected in Donner Pass from 17 June-26 August 1960 and recorded H. juba from 17 June-l July only. My records, given below, corroborate this spring flight but also indicate an autuinn flight missed by the Emmels: Spring Year Locality Spring dates Fall dates snowpack 1972 Boreal Ridge v. 24-vi. 7 viii. 10-x. 4 light 1973 Soda Springs-Norden not seen ix. 7-x. 5 heavy 1974 vi. 9 viii. 24-ix. 27 heavy 1975 vi. 11 ix. 2-ix. 30 moderate 1976 v. 14-vii. 1 viii. 20-x. 8 very light 1977 vi. 4 ix. 2-ix. 23 light 1978 vi. 14-vii. 1 viii. 15-x. 23 very heavy 1979 vi. I-vii. 12 ix. 4-ix. 30 moderate This is an unusual phenology for a skipper, especially in montane habitats. The fall flight appears just as rabbitbrush (Chrysothamnus nauseosus (Pall.) Britton, Compos­ itae) comes into flower and ends just as the last individuals of that species go to seed. During this time nightly low temperatures are usually near to below O°C. Twenty or more H. juba may be found on individual rabbitbrush plants, and they are rarely seen elsewhere: feeding occurs throughout the day if the sun is shining and the air warm. Many other insects also visit Rabbitbrush at this time, including tachinid and syrphid flies, a wide variety of bees including Bombus spp., several day-flying noctuid moths, and such butterflies as Vanessa virginiensis Drury and Polygonia zephyrus Edwards (Nymphalidae), Apodemia mormo Felder & Felder (Riodinidae), Neophasia menapia Felder & Felder (Pieridae), and Ochlodes sylvanoides Boisduval (Hesperiidae). All of the autumn H. juba are fresh, with bright green ventral hindwings bearing lustrous silvery spots; only at the very end of the flight, in October, do any individuals show noticeable wear or fading, and this is uncommon. In spring H. juba appears shortly after snowmelt, often flying on warm south slopes while the north-facing ones are under 2 m of snow. At this time most flower visits are to dandelion (Taraxacum officinale L., Compositae) but many individuals can be seen "body basking" on the bare ground in sunlight, courting, and ovipositing. The popu­ lation density in spring is consistently about one-tenth of the previous autumn's levels, and contrary to MacNeill's observations there has been little year-to-year variability in numbers. The spring flight is very short, often observed only in one weekly sample. In 1976, a year of record low snowpack, H. juba was fairly common on 14 May and singletons were seen weekly to 1 July. Most strikingly, the average condition of spring individuals is much poorer than in autumn. Although a few could be called "fresh" in appearance, most have the green faded to dull brown and the silver entirely lost. Under a dissecting microscope such specimens show up to 20% scale loss on the ventral hind wing. Dorsally the golden ground color is usually intact but the dark borders appear somewhat faded. All this points to adult hibernation. Of the five species of butterflies listed above as visiting rabbitbrush, the two nymphalids reappear at the same time as H. juba and are generally considered to be hibernators. Like H. juba they are very fresh in autumn but appear relatively worn in spring. Also like H.juba, they feed almost continuously from rabbitbrush in good weather. The other three species do not hibernate as adults and have only an autumn flight. They all feed only at midday to mid-afternoon. Adult hibernation has never been reported in the family Hesperiidae in rigorous climates, but the circumstantial case for it at Donner Pass is duplicated by admittedly less mas­ sive documentation in Trinity, Sierra, Plumas, Siskiyou, Shasta, and Alpine Counties. 260 JOURNAL OF THE LEPIDOPTERISTS' SOCIETY In the Great Basin at lower elevations H. juba also flies at rabbitbrush season and engages in massive, continuous flower visitation. Could a spring generation emerge in June from eggs laid the past September at Donner? It is difficult to see how. Skippers grow slowly as a rule; in optimal weather development from a June egg to a fall adult requires 8-11 weeks. A September egg would have, on the average, 6 to 8 weeks before continuous snow cover developed. During this time the days are shortening rapidly, and ambient temperatures exceed 10°C for only a few hours a day while nightly minima may reach _10°. An increasing number of days have little or no sunshine. MacNeill found that captive larvae kept outdoors in the San Francisco Bay Area would not feed in cool, cloudy weather but resumed activity immediately in strong sunshine or at indoor temperatures. It is dif­ ficult to envision much activity or growth after early October at Donner, and impossible to envision under snow. Moreover, the grasses are in poor condition at this time. The most important spring host seems to be Agrostis idahoensis Nash, which is mostly brown in October but grows rapidly after snowmelt. After snow leaves an area adults are generally not seen for 2 or 3 weeks. Ambient temperatures are often high and the days are quite long, but this is a very short developmental time for a skipper! Moreover, most of the H. juba at Donner in spring are worn when first encountered. If little or no wear is shown by fall adults three weeks into the flight, why should newly emerged spring animals deteriorate so rapidly? It is not inconceivable that H. juba could have a "mixed strategy" of overwintering as adults, eggs, and perhaps young larvae. The two latter stages are common among Hesperiines. Absolute proof of overwintering will require detection of hibernating adults in midwinter, or the recapture in spring of individuals marked the previous autumn. In the absence of such direct evidence the inferential case is rather compel­ ling. ARTHUR M. SHAPIRO, Department of Zoology, University of California, Davis, Cal­ ifornia 95616. Journal of the Lepidopterists' Society 33(4), 1979,260-261 A MIGRATORY FLIGHT OF URANIA FULGENS (WALKER) IN HONDURAS (URANIIDAE) Urania fulgens has long been known as a migratory diurnal moth.