Rhododendron cicada
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Rhododendron cicada ( Graphocephala fennahi ) |
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| DA Young , 1977 |
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The rhododendron cicada ( Graphocephala fennahi , syn .: Graphocephala coccinea ) is a round head cicada from the family of the small cicadas (Cicadellidae) and the only species of the genus Graphocephala in Europe.
features
The cicadas reach a body length of eight to nine millimeters. Their body color, which is unmistakable for Central European species, is very colorful. The top of the pronotum and the forewings have a strong green base color. The pronotum bears several orange spots, some of which flow into one another, the forewings each have two slightly sloping orange longitudinal lines, both of which end at the inner edge of the wing. Like the hind wings, the edge of the wing tip is dark purple in color. The legs , abdomen and head are colored yellow. The latter has a purple to dark colored stripe on the forehead that runs over the compound eyes to below the edge of the pronotum. The scutellum is orange.
Occurrence
Originally native to North America, the species is believed to have been introduced to southern England with rhododendron plants in the early 1930s. At the end of the 1960s it was also found in continental Europe, where it has spread almost everywhere and is common to this day. In Germany the cicada was first detected in 1978 in Mönchengladbach. The animals live in parks, cemeteries and gardens where rhododendrons were planted.
Way of life
The larvae feed exclusively from the sap of the rhododendrons , which imagines suck occasionally on other plants such as ivy ( Hedera helix ), Linden ( Tilia ), sycamore ( Platanus ) or maple ( Acer ). You can often see the animals in large numbers while sunbathing on the upper side of the leaves. In the event of faults, the underside of the leaf is sought. The species produces one generation per year, overwintering as an egg in the flower buds. The yellowish larvae hatch at the end of April and begin to suckle on the underside of the leaves. After multiple moults, both the very agile larvae and empty larval skins can be observed in May and June. At the end of June the full insects develop, which can be found until November.
Harmful effects
The rhododendron bushes often show staining of the leaves due to the sucking activity and sometimes leaf fall with a high individual density of the cicadas. The cicada also transmits the North American fungus Pycnostysanus azaleae , which can cause brown, dead buds on rhododendron bushes. The infestation is favored by small slits that the rhododendron leafhoppers cut into the bud scales when they lay eggs in late summer and autumn. Fungal spores adhering to the cicadas are entered into these injuries. There the mushroom finds ideal living conditions. The extent of the damage only becomes apparent in spring when the flower buds fail to emerge. The flower buds turn gray to brown over the winter and eventually die off. The dried buds remain mummified on the bush. About 2 millimeters long “rods”, the fruiting bodies of the fungus, grow out of the buds. These outgrowths prevent fungal infestation with Pycnostysanus from other fungal diseases such as B. gray mold or flower buds damaged by frost. The fungus can also penetrate down the branch and cause it to die.
Biological agents based on natural pyrethrum or insecticides obtained from neem trees are suitable for controlling the cicadas and their larvae . They should be applied to the underside of the leaves in the morning hours in order to also control the larvae. The use of so-called yellow panels is also possible. They are hung in the infested bushes. The cicadas - but also many other insects - stick to them. These boards are usually insecticide-free.
In addition, it is strongly recommended to pluck the brown or black, dead buds - meaningfully before the hatching time of the cicada (April) - and not to drop them and not to compost, but to throw them directly into the household waste.
Sources and further information
Individual evidence
- ↑ Integrated plant protection rhododendrons - pests, diseases, yellowing. Bavarian State Institute for Agriculture (online PDF) .
- ↑ Rhododendron leafhopper: A fungus that is transmitted by the rhododendron leafhopper causes the buds of the ornamental shrub to die off. This is how you recognize and fight the pest. in mein-schoener-garten.de
literature
- Heiko Bellmann : The new Kosmos insect guide , Franckh-Kosmos, Stuttgart 1999, ISBN 3-440-07682-2
- R. Remane, E. Wachmann: Cicadas - get to know, observe - Naturbuch Verlag, Augsburg 1993, ISBN 3-89440-044-7
- H. Nickel: The leafhoppers and planthoppers of Germany (Hemiptera, Auchenorrhyncha): Patterns and strategies in a highly diverse group of phytophagous insects. Pensoft, Sofia and Moscow, 2003, ISBN 954-642-169-3
Web links
- Graphocephala fennahi at Fauna Europaea
- www.natur-in-nrw.de