:'''Symphyta' redirects here. For the
moth genus, see ''
Symphyta (moth).
'Sawflies' make up the suborder 'Symphyta', a group of largely
phytophagous insects in the order
Hymenoptera. This group is an artificial assemblage of superfamilies (the overall group is
paraphyletic), but the name is still in common use, and treated as a suborder, though it seems likely it will be phased out in future classifications. These superfamilies are essentially the most primitive taxa within the Hymenoptera (some going back 200 million years), and one of the taxa within the Symphyta gave rise to the suborder
Apocrita (
wasps,
bees and
ants - this group is considered
monophyletic). In the opinion of many experts, the most likely
sister taxon to the Apocrita is the family
Orussidae, the only Symphytan group which is
parasitic.
Sawflies are distinguishable from most other Hymenoptera by the broad connection between the
abdomen and the
thorax ''(see image)'', and the caterpillar-like larvae (below). The common name comes from the appearance of the
ovipositor, which looks much like the blade of a saw. This ovipositor, which is modified into a "
sting" in some members of the Apocrita, is not used as a weapon. Females use the ovipositor to cut into plants where they lay their eggs. A few species have long thin ovipositors used to drill holes deep into wood. Large populations can cause economic damage in cultivated areas and forests.
The larvae look like caterpillars (the larvae of moths and butterflies), with two notable exceptions; (1) they have five or more
prolegs on the
abdomen (caterpillars have five or fewer), and (2) they have two
ocelli instead of the caterpillar's six. Typical sawfly larvae are
herbivorous, the group feeding on a wide range of plants. Individual species, however, are often quite specific in their choice of plants used for food. The larvae of various species exhibit
leaf-mining, leaf "rolling", or
gall formation. Three families are strictly
xylophagous, and called "
wood wasps", and one family is parasitic. The larvae that do not feed externally on plants are grub-like, without prolegs.
Adult sawflies, except for those in the family
Cephidae, have structures that latch onto the underside of the forewings to help hold the wings in place when the insect is at rest. These "
cenchri", which are absent in the suborder Apocrita, are located behind the
scutellum on the thorax. Adults of some species are carnivorous, eating other insects, but many also feed on nectar.
External links
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Sawfly - Tenthredininae subfamily - diagnostic photographs and information
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Sawfly - ''Dolerus unicolor'' photos and information
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Sawfly - ''Dolerus nitens'' photographs
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Sawfly ''Arge humeralis'' photographs
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''A sawfly injurious to young pines'' hosted by the
UNT Government Documents Department
References
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The American Museum of Natural History 2004-01-15
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Kendall Bioresearch Services (Image)