Tomostethus

Konow, 1886

ash sawflies

Species Guides

Tomostethus multicinctus(brownheaded ash sawfly)

Tomostethus is a of in the Tenthredinidae, first described by Konow in 1886. within this genus are associated with ash trees (Fraxinus spp.) and are recognized as pests of economic and ecological significance. The genus includes species such as T. nigritus, T. multicinctus, and T. sinofraxini, which have been documented across Europe and Asia. Several species have shown capacity for , particularly in urban environments.

Tomostethus gracilicornis by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Tomostethus: /təˈmɒstɪθəs/

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Identification

Tomostethus are distinguished from other by their association with ash (Fraxinus) and their placement within the Tenthredinidae . Specific diagnostic morphological features for the genus are not documented in the available sources. Species-level identification requires examination of specimens.

Images

Habitat

Associated with ash trees (Fraxinus spp.), including urban environments and city infrastructure. T. nigritus has been observed utilizing city infrastructure for rapid spread.

Distribution

Europe: documented in Belgium, Denmark, Norway, Sweden, and the Republic of Ireland. Asia: T. sinofraxini is to Beijing, Tianjin, Hebei, and Shandong provinces in China.

Seasonality

timing is influenced by temperature; higher March temperatures have caused earlier emergence in T. nigritus . Phenological synchronicity with tree foliage emergence is a critical factor in .

Diet

Phytophagous; larvae feed on ash foliage. T. sinofraxini feeds on Fraxinus chinensis; T. nigritus feeds on Fraxinus excelsior and Fraxinus angustifolia 'Raywood'; T. multicinctus attacks Fraxinus spp.

Host Associations

Fraxinus chinensis - Chinese ash; primary of T. sinofraxini
Fraxinus excelsior - European ash; native of T. nigritus
Fraxinus angustifolia 'Raywood' - Non- cultivar; documented in Belgium

Life Cycle

T. sinofraxini development includes , larval, and stages. Developmental duration varies with temperature: at higher altitudes with lower average temperatures, egg, larval, and adult stages were 19%–31% longer than at lower elevations.

Behavior

can occur on non- trees. T. nigritus has demonstrated rapid spread using city infrastructure. appear linked to phenological synchrony with host foliage . Some evidence suggests dramatic decline after reaching peak levels, though the mechanism remains unexplained.