Longitarsus jacobaeae

Small flea beetle with enlarged hind femora adapted for jumping. Distinguished from other Longitarsus species by strong association with tansy ragwort; positive identification requires examination of male genitalia or expert taxonomic verification.

Open grasslands, pastures, and disturbed areas where tansy ragwort occurs.

Native to Europe; introduced to North America, Australia, and New Zealand for biological control. GBIF records confirm presence in Europe, North America, and Australia.

Active spring through early summer (May–July) and late summer through autumn (August–October). Adults enter summer aestivation in mid-summer (July) and winter inactivity (January), during which they do not respond to host plant odors.

Adults and larvae feed exclusively on tansy ragwort (Senecio jacobaea). Adults consume foliage; larvae mine roots and crown tissue.

• Senecio jacobaea - OBLIGATETansy ragwort; sole host for feeding and reproduction. Highly host-specific; does not attack native Senecio species in New Zealand or economically important plants.

Complete metamorphosis. Adults emerge in spring, feed on foliage, and oviposit at base of host plants. Larvae develop in roots and crown, pupating in soil. New adults emerge in late summer. Italian biotype exhibits adult aestivation during summer months.

Adults orient to upwind host plants using olfactory cues, responding to plants 60–300 cm away. Starved individuals show directed upwind movement; satiated beetles move randomly. Males are attracted to volatiles from females, female feces, and host plants fed upon by females, but not to clean host plants or male feces. Synthetic jacobine (a pyrrolizidine alkaloid from tansy ragwort) attracts males when combined with host plant volatiles.

Specialist herbivore; primary biological control agent reducing tansy ragwort populations. Works in combination with cinnabar moth (Tyria jacobaeae) and ragwort plume moth (Platyptilia isodactyla) in integrated weed management programs.

Widely used biological control agent for tansy ragwort in pastures and rangelands. Reduces reliance on chemical herbicides. Success documented in New Zealand, where combined bio-agent pressure has reduced ragwort from dense infestations to negligible levels within several years.

• Other Longitarsus speciesMany Longitarsus are flea beetles with similar morphology; L. jacobaeae distinguished by host specificity and association with tansy ragwort.
• Cinnabar moth (Tyria jacobaeae)Shares host plant and biological control role; distinguished as lepidopteran with conspicuous black-and-red warning coloration, versus coleopteran flea beetle.

• flea beetle
• biological control
• ragwort
• herbivore
• invasive species management
• Chrysomelidae

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Senecio jacobaeae Archives - Entomology Today
• Meet six unsung heroes of the pollination world - Buglife Blog - Buglife
• New Zealand Farmers use Moths and Beetles to Fight Weeds
• Host specificity of the ragwort flea beetle Longitarsus jacobaeae (Waterhouse) (Coleoptera:Chrysomelidae)
• Attraction of Longitarsus jacobaeae Males to Cues Associated with Conspecific Females (Coleoptera: Chrysomelidae)
• Factors affecting the response ofLongitarsus jacobaeae(Coleoptera: Chrysomelidae) to upwind plant odours
• Responses of ragwort flea beetleLongitarsus jacobaeae(Coleoptera: Chrysomelidae) to signals from host plants
• Longitarsus jacobaeae (Coleoptera: Chrysomelidae), a Flea Beetle for the Biological Control of Tansy Ragwort. 1. Host Plant Specificity Studies2
• Field and laboratory observations of the life history of the Swiss biotype of Longitarsus jacobaeae (Coleoptera: Chrysomelidae).
• Longitarsus jacobaeae (Coleoptera: Chrysomelidae), a Flea Beetle for the Biological Control of Tansy Ragwort. Ii. Life History of a Swiss Biotype2
• Longitarsus jacobaeae (Coleoptera: Chrysomelidae), a Flea Beetle for the Biological Control of Tansy Ragwort. 4. Life History and Adult Aestivation of an Italian Biotype2