This work presents the results of a molecular investigation (mtDNA: COI) of Nearctic Euchloe species. The five hitherto accepted species, E. creusa (Doubleday & Hewitson, 1847), E. hyantis (W.H. Edwards, 1871), E. guaymasensis Opler, 1986, E. olympia (W.H. Edwards, 1871), and E. ausonides (Lucas, 1852), are supported. They are part of the species groups II and V of the existing phylogeny of Palaearctic Euchloe species (Back et al. 2008). The subspecies so far described, as well as additional populations with respect to ecology and phenotype, show no or little sequence divergences and we conclude that these represent intraspecific variation. This lack of divergence appears for members of the Euchloe hyantis complex where we assert that biological and phenotypic characters indicate that species-level isolation has been attained for E. hyantis, E. lotta Beutenmüller, 1898 and E. andrewsi Martin, 1936, respectively. Interestingly, there are also no differences between Nearctic and Siberian populations of E. creusa. Despite these findings, E. ausonides is supported as a discrete species, while its affiliation to species group V points towards a certain relationship to E. ausonia (Hübner, 1804). However, it is evident, that all samples of E. ausonides ogilvia Back, including one specimen with a dark color pattern that resembles E. ausonia naina Kozhantshikov, are genetically very similar to E. ausonides, which leads to consideration of E. ogilvia as a subspecies of E. ausonia. The occurrence of the Palearctic species E. ausonia naina in Yukon Territory is not treated, because we lacked material suitable for DNA analysis. The species status of the most recently described E. guaymasensis was also reaffirmed. Although this species shows some similarities in phenotype and haplotype to E. hyantis, our genetic analysis, especially the COI DNA sequences detected a closer relation to E. olympia. In fact, there are also specific similarities in phenotype between these two species. E. olympia is distinct according to both phenotype and genetic features. Phylogenetic assignment is not explicit. While the more conservative method of nuclear DNA comparison points towards a closer relationship to E. ausonides, analysis of the faster-evolving, maternally-inherited mitochondrial COI gene shows a closer relatedness with E. hyantis and especially with E. guaymasensis. Male Euchloe use either ridge and peak patrolling or drainage course patrolling as mate location strategies. Use of these disparate strategies by sympatric species may be most important as a barrier to hybridization and may serve as a mechanism for speciation.

Each spring, Vanessa cardui (Linnaeus) migrates into Europe, sometimes in huge numbers. Although it is widely accepted that migrants come from North Africa, there is currently a dearth of information on the source areas they originate from. However, in a recent study, a strong association between V. cardui arriving in spring in Catalonia (NE Spain) and synoptic-scale winds originating in North Africa was found, which allowed us to predict the most likely location for the source areas in the Maghreb. In March 2009 we organized an expedition to confirm in situ the occurrence of immature stages and/or emerging adults at one of the hypothetical breeding areas in Morocco. Immatures were found at virtually all the sampled sites, with the maximum abundance being recorded in the Souss valley. Breeding habitats with plenty of thistles and mallows were sufficiently common to permit populations of great density to build up. We found a massive emergence site of 1.8 ha with an estimated population of 170,000 larvae, of which 155,000 had successfully pupated, the rest having been parasitised by the wasp Cotesia vanessae. Bird predation of adults was also recorded at this site. Our observations, together with the typical patchy distribution of the ruderal habitats used for breeding, suggest that source populations most frequently originate in small habitat pockets with favourable conditions that allow for high patch occupancy and levels of oviposition.

During winter, monarch butterflies form dense colonies in oyamel fir forests on high mountains in central Mexico, where the forest canopy serves both as a blanket, moderating temperature, and an umbrella, shielding the butterflies from rain. In this study we investigated the vertical dimension of the butterflies' use of the oyamel forest: we predicted that clusters form at the heights above ground that provide the greatest protection from freezing. By suspending temperature recorders at eight heights, from ground level up to 22m, we established two vertical transects in the forest. We set one transect in a densely forested area and the other in a thinned area, and we recorded hourly temperatures from Jan 13 through Feb 5, 2006. Intermediate heights in the forest, from 10 to 15m above ground, remained the warmest during the cold night and early morning. We also determined that this temperature distribution matched available records of the vertical distribution of butterflies roosting in branch and trunk clusters. The vertical temperature profiles became uniform during mid-day. Temperature extremes were moderated more during clear than during cloudy periods and more in the denser than in the thinned forest. Our results illustrate how the monarch butterfly is behaviorally adapted to the three-dimensional complexity of microclimate in the oyamel forest. A denser forest provides better protection for the overwintering survival of monarch butterflies than a thinned forest. This research bolsters our other microclimatic studies, all of which point to the urgency of prohibiting logging within the oyamel forest used as wintering habitat by monarch butterflies.

A new species of Euclemensia (Cosmopterigidae) is described from Louisiana. The imago and genitalia of the male and female are illustrated, and diagnoses are provided to differentiate the new species from the four other described species of the genus.