Characteristics
- No wasp waist: broad junction between thorax and abdomen
- Wings with complete venation, no longitudinal folding
- Filiform antennae, sometimes short or pectinate
- Ovipositor shaped like a saw, used to cut into plant tissues
- Larvae with more than 5 pairs of prolegs, without crochets (unlike caterpillars)
Notable Families
- Tenthredinidae – Common sawflies, larvae on many plant species
- Cimbicidae – Large robust sawflies with pectinate antennae
- Argidae – Simple antennae, often gregarious larvae
- Diprionidae – Larvae on conifers, sometimes considered pests
- Siricidae – Wood wasps, larvae develop inside trunks
- Xiphydriidae, Pergidae – Exotic or rare families
Habitat
Symphyta can be found in:
- Deciduous and coniferous forests
- Hedgerows, forest edges, gardens, orchards
- Humid environments (some species linked to alders, willows, etc.)
- Tree trunks or stumps (for xylophagous species)
Biology
Adults are floricolous or discreet
Larvae:
- Herbivorous (leaves, stems, sometimes roots or wood)
- Active in plain view on vegetation
- Some species are gregarious and capable of mass defoliation
Often univoltine, sometimes bivoltine cycles
Pupation occurs in soil or wood depending on species
Distinctive Features
- Resemble wasps, but lack the narrow waist
- Larvae often mistaken for caterpillars but differ morphologically
- Some xylophagous species (e.g. Sirex) are associated with symbiotic fungi
- Ecological importance as herbivores, prey, or bioindicators