Necydalis ulmi Chevrolat, 1838

Subfamilia: LEPTURINAE  /  Tribus: NECYDALINI

necydalis ulmi (bezděz mt.)

necydalis ulmi (bezděz mt.)

necydalis ulmi (bezděz mt.)
Photo © M.Hoskovec


Necydalis ulmi (Bezděz)
Photo © M.Hoskovec

Necydalis ulmi Chevrolat, 1838 is a remarkable insect species of the West-Palaearctic region. The species is distributed throughout Central and South Europe, and the Caucasus, reaching the Transcaucasian region, and requires old well preserved broad-leaved forests (cf. Figure 1) growing in altitudes ranging from 0 to 800 metres above sea level. A paper dealing with larval nutrition and female oviposition preferences of some Necydalis species has appeared recently (Rejzek and Vlasák, 2000[1999]). In this paper the biology of Necydalis ulmi is summarised in the following way:

"Necydalis ulmi develops primarily in Fagus sylvatica, Quercus cerris, and Aesculus hippocastanum. As alternative host plants other Quercus spp., Ulmus, Carpinus, Celtis, Tilia, and also Fraxinus, Populus, Salix, and Juglans should be named. The larvae of Necydalis ulmi develop in a substrate present in the inside of hollows of living trees (cf. Figure 2). These hollows are created by two species of polyphores: Inonotus obliquus (cf. Figure 3a) and Inonotus cuticularis (cf. Figure 3b). The inside of a typical hollow is in parts covered with a thin and dry black layer (cf. Figure 4). Next there is a thick layer of a quite moist, red-brown to yellow decayed wood, followed by the firm heartwood, and finally the living tissue (sapwood). The red-brown to yellow wood that comprises the larval substrate has a spongy-fibrous structure typical for wood decayed by various white rot (ligninolytic) fungi. Their mycelium regularly create a yellow to red-brown circle surrounding the larval galleries (cf. Figure 5). This mycelar circle is well recognisable on the substrate background and serves as a clear hallmark of the species presence. The convenient substrate is not only present inside the hollows, but it is also regularly present inside a substantial part of the living trunk, especially in the part above the hollow entrance. The substrate completely surrounded by living tissue is of a different colour to the insides of the hollows. It is usually light yellow and therefore the mycelar circles surrounding the larval galleries are more clearly visible because the circles are of a contrasting red-brown colour. Sometimes, the entrance into the hollow is small and hardly visible, and although the tree seems to be perfectly sound, a substantial part of the heartwood is decayed, infested by fungi, and by larvae (cf. Figure 6) of Necydalis ulmi."



Body length:18 - 35 mm
Life cycle:3 - 4 years
Adults in:June - August
Distribution:Central and South Europe, Caucasus, Transcaucasia

The mounted beetle and living beetle in the upper pictures were collected in a hollow trunk of an old living beech tree (Fagus sylvatica) in Bezděz Mt. (North Bohemia, Czech Republic). The living beetle in the lower pictures was reared from a larva collected in a hollow trunk of a living beech tree (Fagus sylvatica) in Křivoklát (Rejzek and Rebl, 1999), Central Bohemia (Czech Republic).

Collected by M.Rejzek and M.Hoskovec.


Necydalis ulmi (Křivoklát)

Necydalis ulmi (Křivoklát)
Photo © M.Hoskovec



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MH & MR © January 14, 2010