Thymelicus lineola

Distinguished from the similar Small Skipper (Thymelicus sylvestris) by the black tip of the antenna club, which extends along the upper edge (T. sylvestris has an orange tip). The sex brand on the male forewing is a short, straight line rather than the longer, curved line found in T. sylvestris. Underside of hindwing is greenish-gray. Wingspan approximately 24–28 mm.

Grassy areas including meadows, pastures, roadsides, and hayfields. In Europe, agricultural practices have reduced its presence in hayfields. Larvae develop on various grasses. Adults require sunny conditions for activity and avoid shaded areas for oviposition.

Native to Europe and northern Asia. Introduced to North America prior to 1910, with established populations throughout southern Ontario, Quebec, Manitoba, and parts of the northern United States including Michigan, Ohio, New York, Pennsylvania, Maryland, New Jersey, and Connecticut. Range extends west to British Columbia.

Univoltine. Adults active from late June to August in North America, with peak activity varying by region and year. Egg, larval, and pupal stages occur during remainder of year.

Larvae feed on grasses including timothy (Phleum pratense), orchard grass (Dactylis glomerata), and other Poaceae. Adults feed on nectar from various flowers.

Five larval instars. Eggs are laid on grass stems. Larvae feed within silken tubes on host grasses, overwinter as partially grown larvae, and complete development in spring. Pupation occurs in silken cocoons among grass stems or debris. Adults emerge in summer.

Males perch on grass stems and dart at passing objects to detect females. Courtship involves pursuit, hovering near perched females, and release of pheromones from androconial scent scales on forewings; osmophores break off during courtship to release pheromone. Females exercise mate choice and may reject males through evasive flight. Both sexes bask with wings held in characteristic posture to elevate thoracic temperature; basking occurs when black globe temperature exceeds 20°C. Males divide time equally between flying and feeding in warm weather; females spend majority of time feeding.

Larval herbivore on grasses. Adults may incidentally interfere with pollination of some orchids (e.g., Cypripedium reginae) by becoming trapped in flowers, potentially reducing seed development. Serves as host for multiple parasitoid species in Europe including Stenichneumon scutellator, Rogas tristis, and Phryxe vulgaris.

Considered a pest of timothy hay in North America, where larval feeding reduces forage quality. Subject to control efforts including cutting infested areas before adult emergence or application of Bacillus thuringiensis. Transported unintentionally via contaminated timothy seed. Target of biological control research involving introduction of European parasitoids to North America. Genome sequenced as part of Darwin Tree of Life project.

• Thymelicus sylvestrisSimilar size, habitat, and appearance; distinguished by orange (not black) antenna club tip and longer curved male sex brand
• Thymelicus acteonLarger size and more southerly distribution in Europe; male has more extensive sex brand

• skipper
• grass-feeder
• introduced species
• pest
• thermoregulation
• pheromone
• parasitoid host
• genome sequenced

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
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• Mate Location and Mating Behavior of Thymelicus lineola (Lepidoptera: Hesperiidae)
• THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE) AND ITS PARASITES IN EUROPE
• SAFETY TESTS FOR THE BACULOVIRUS OF THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE)
• European skipper butterfly (Thymelicus lineola) associated with reduced seed development of showy lady’s-slipper orchid (Cypripedium reginae)
• THE NUMBER OF LARVAL STAGES OF THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE) IN EASTERN CANADA
• The Present Status of the Introduced Skipper, Thymelicus lineola (Ochs.) (Lepidoptera: Hesperiidae), in North America and Possible Methods of Control
• RANGE EXTENSION FOR THE EUROPEAN SKIPPER, THYMELICUS LINEOLA (OCHSENHEIMER), 1808 (LEPIDOPTERA: HESPERIIDAE), IN MANITOBA
• KNOWN DISTRIBUTION OF THE EUROPEAN SKIPPER, THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE), IN QUEBEC
• TRANSPORT OF THE EUROPEAN SKIPPER, THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE), ASSOCIATED WITH THE PRODUCTION OF CERTIFIED TIMOTHY SEED
• SEASONAL BIOLOGY IN QUEBEC AND PREDICTION OF PHENOLOGY OF THE EUROPEAN SKIPPER,THYMELICUS LINEOLA(LEPIDOPTERA: HESPERIIDAE)
• Diel patterns of activity of Thymelicus lineola adults (Lepidoptera: Hesperiidae) in relation to weather *
• Expanding Distribution and Evolutionary Potential of Thymelicus lineola (Lepidoptera: Hesperiidae), an Introduced Skipper, With Special Reference to its Appearance in British Columbia
• The role of the androconia in the mating behaviour of the European skipper, Thymelicus lineola, and evidence for a male sex pheromone
• European Skipper Butterfly (<i>Thymelicus lineola</i>) Associated with Reduced Seed Development of Showy Lady’s-slipper Orchid (<i>Cypripedium reginae</i>)
• The genome sequence of the Essex Skipper butterfly, Thymelicus lineola (Ochsenheimer, 1808).