Sluggish weevil
Distelgallenrüssler
The Distelgallenrüssler ( Cleonis pigra, formerly erroneously piger ) is a beetle of the weevil family and the subfamily Lixinae. The scientific genus name is Cleonis AltGr. κλέος kleos " glory " is derived. The species name piger (Latin ) means "slow". The German name " Distelgallenrüssler " is explained by the fact that the larval feeding in the thistle roots gall formation causes.
Characteristics of the beetle
The clunky -looking black body is densely hairy white gray woolly. The slurred drawing on pronotum and elytra is due to different degrees of hairiness and so varies with each appearance of the dark body color. The more the hair is worn, the darker the Beetle appears. The body length varies between ten and sixteen millimeter.
The mouthparts are on an extension of the head forward, the trunk. The trunk is angular and flattened on the top. It is longer than the rest of the head. On top of the trunk bears three longitudinal furrows, of which the middle reaches of the pronotum. The longitudinal furrows are light haired and separated by keels, the lateral longitudinal grooves are defined externally by a keel. There are so visible from the top four keels and three troughs. Under the side keel stems from the probe, the base of which can be inserted into a current at 45 degrees downward groove-like furrow. These sensors furrow can not be seen and reached far from the eyes, the underside of the snout from above.
The geknieten sensor consist of a strong on the outside keulig thickened stem which hardly reaches the anterior margin. The following is a thick seven-membered scourge to which a tightly attached and long oval leg connecting. The first whip element is longer than the second. The roundish eyes are on the side of the head, slightly arched, oval, and much higher than wide.
The pronotum bears on each side, two more or less distinct light longitudinal bands, a wider top lying on the side and in parallel on the inside a narrower, which rises approximately at the level of the outer keels of the proboscis. The anterior margin of the pronotum is laterally at the bottom of the front extended (eye lobes). The pronotum is usually keeled, the keel before the middle wide pressed something. As the base of the elytra is set with shining grains and the pronotum.
On each wing covers are three often indistinct oblique dark binding that to run at about 45 ° from the front to the rear outside to the inside seam. The scutellum is small but clearly visible.
The powerful legs have four-membered tarsi. The three Tarsenglieder are short, the first longest, the other two approximately equal length.
Biology
The larvae develop in the root collar of various thistle plants ( Nodding Thistle, Thistle Way, Spear Thistle, Creeping Thistle, cabbage thistle, cotton thistle, milk thistle, Woolly Thistle ) as well as Greater and Lesser Burdock. Beetles were also drawn from the root galls of different types Knapweed (Centaurea maculosa, Centaurea diffusa, Centaurea arenaria ). However, the main host is the creeping thistle.
Imagines are to be found throughout the year, the new generation will appear in August. The adult animals hibernate. The females lay in the following year in mid- April to the end of June their eggs in the root collar, the lower stem area or even in the base of the midrib of the leaves from. The larvae eat their way down to the root. The root develops around the feeding site a spindle-shaped gall. Pupation takes place in the root.
According to the spectrum of host plants encountered the Beetle Although frequently but not exclusively in warmer and drier habitats on.
Dissemination
The Palaearctic species is found in Europe, except in the northern parts of Scandinavia almost everywhere and is the most common type of the tribe. In the south, it is also found in North Africa, to the east, the area of distribution over Siberia, Mongolia and China expands to the Pacific Ocean from.
The Beetle is also reported from North America.