| Tenthredo of the marginella group (Tenthredo marginella-thompsoni (Fabricius, 1793 - Curtis, 1839)) |
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Scientific name: Tenthredo marginella-thompsoni (Fabricius, 1793 - Curtis, 1839) Common name: Tenthredo of the marginella group French name: Tenthredo du groupe marginella Order: Hymenoptera Family: Tenthredinidae Wingspan : 9-12 mm. Biotope: Damp meadows. Geographic area: Tenthredo marginella : Central and southern Europe, North Africa, the Caucasus and Central Asia. Tenthredo thompsoni : Central and southern Europe. Observation period : Larvae are observed from September to November, Imagos just before. |
Sawflies are Hymenoptera with no wasp-like waist between thorax and abdomen. Females' ovipositor show some kind of saw-like genitalia, located inside a sheath. It is used to cut out plants in order to lay the eggs. You cannot differentiate sawflies Tenthredo marginella and Tenthredo thompsoni on a picture. These are black and yellow insects. The head is black, the upper part is punctuated and appears dull. The clypeus and the base of the mandibles are yellow. The antennae, of 9 articles, show one yellow article at the base while all the other ones are black. The angles of the pronotum are yellow. There is one or two yellow patches on the scutellum. The abdomen is black with one yellow stripe on the first, fourth and fifth tergites. The stripe on the fifth tergite may be interrupted. The tip of the abdomen shows one median yellow patch on the seventh tergite and completely yellow eighth and ninth tergites. There are sometimes lateral yellow patches on the sixth tergite. The legs are mainly yellow. The femora are black except on the tips and sometimes on the under side of femur 1 which is yellow. The tarsi are black or brown. The wings are darkened in the radial zone. The stigma and the costal vein are pale yellow. There are several similar species and here is some information to try to tell them apart. Tenthredo vespa has a completely black scutellum, without any yellow marking. Tenthredo zona has the two first articles of the antennae which are yellow. Tenthredo amoena has a smooth upper side of the head. Other species like Tenthredo scrophulariae have yellow or reddish antennae. This is only a short list ... The larvae of Tenthredo marginella look like caterpillar as all other sawfly larvae. They are dark greyish with a black head. They show one large yellow patch on both sides of each segment with one black patch above and another one below. They grow on Mint (Mentha), Plantain (Plantago) and some other low growing plants. |
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I Think that this saw fly shows most of the characteristics of the Tenthredo marginella-thompsoni group. The upper side of the head is punctuated. Only the first article of the antennae is yellow. You can see one yellow patch on the scutellum. I have been intrigued by the colour of the tarsi at first, but I have read that they can be black or brown. They are rather light coloured here … The large number of species in this genus, their similarities and variations, do not make me quite sure of this species identification. |
André Bon September 2013