The iris sawfly (''Rhadinoceraea micans'') is a species of

sawfly Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...

in the family ''

Tenthredinidae Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem ...

''. Native to Europe, the larvae — more often noticed than the adults — can occur in large numbers causing damage to garden plants such as the yellow iris or flag, ''

Iris pseudacorus ''Iris pseudacorus'', the yellow flag, yellow iris, or water flag, is a species of flowering plant in the family Iridaceae. It is native to Europe, western Asia and northwest Africa. Its specific epithet ''pseudacorus'' means "false acorus", ref ...

''.

Description

Adult

The adult sawfly is shiny, black, and hairy. The antennae are thick, and longer than head and thorax combined. The wings are slightly smoky. The head is as wide as the thorax.

Larva

The larvae, up to 1 inch (25 mm) long, look like caterpillars but have six pairs of

proleg A proleg is a small, fleshy, stub structure found on the ventral surface of the abdomen of most larval forms of insects of the order Lepidoptera, though they can also be found on other larval insects such as sawflies and a few other types of in ...

s rather than five. The head is shiny black; the body greenish brown, becoming darker with age. There are double rows of white dots around the segments. Larval host plants are all waterside irises, including ''

'', ''

Iris ensata ''Iris ensata'', the Japanese iris or Japanese water iris ( Japanese: ''hanashōbu''), formerly ''I. kaempferi'', is a species of flowering plant in the family Iridaceae, native to Japan, China, Korea and Russia, and widely cultivated as an orna ...

'', '' Iris laevigata'', '' Iris spuria'' and '' Iris versicolor''.

Life cycle and behaviour

The adult iris sawflies lay their eggs in May on the leaves of irises (especially the yellow flag). The eggs are in large flat placards on iris leaves. The female lays the eggs by inserting her "saw" into the blade of the leaf near the thickened middle, not far from the leaf base. As many as 19 eggs may be inserted into separate cells of a single leaf. The larvae eat the leaves until about July and then crawl into the ground. There, they spin cocoons and pupate. They overwinter as pupae. The adults hatch in May of the following year. The adults fly reluctantly and may sham death if touched. The larvae are serious garden pests and can completely defoliate irises, especially the yellow iris, when these are growing by water. Irises on dry ground are however not attacked.

Distribution

The iris sawfly is endemic to Europe, being found in Britain, France, Sweden, Finland, Denmark, the low countries, Germany, Poland, Italy, Bulgaria and Romania. It is absent from Spain, Sicily and the Mediterranean islands, Greece, former Yugoslavia and countries east of Poland.

Bibliography

* Alford, David V. ''Plant Pests''. Collins New Naturalist Library, 2011. * Cameron, Peter.
A monograph of the British phytophagous Hymenoptera (Volume 1)
'' Ray Society. 1882
Archive.org
Entry "''Blennocampa micans''", page 237. * Halstead, Andrew, and Beatrice Henricot. ''Pests and Diseases: simple steps to success''. Royal Horticultural Society/Dorling Kindersley, 2010. .

References

External links

Nearctic sawflies
{{Taxonbar, from=Q7320039 Hymenoptera of Europe Insect pests of ornamental plants Insects described in 1816