Latin: Thaumatomyia notata
Thaumatomyia notata is the Latin name for the yellow swarming fly, which is especially visible in autumn, where it can find its way into habitats to overwinter.
Appearance
The yellow swarming fly is a rather small, as a full-grown fly only grows about three millimeters long. The fly has a yellowish color, while over the back it has several black drawings as well as dark, wide transverse stripes on the hind body.
Biology and behavior
The yellow swarming fly belongs to the family (Chloropidae), a large family of small flies, most of which are associated with plants in the grass family. The yellow swarming fly larvae develop in the plant roots from, especially grass. Here the larvae feed on the small root lice that are under the grass. Each season can offer many generations of new yellow swarming flies, but the fly only overwinters as an adult fly and not as a larva.
During the spring months, the air can swarm by small yellow swarming fly that are on their way out of their wintering grounds and are in search of food. The adult flies’ feeds, among other things, on the nectar that comes from flowers. However, the spring swarms are not at the same height as the swarms that occur in the fall. On hot days in October, invasion-like conditions can even occur, where the flies pull towards buildings where they enter through all openings and cracks. However, these periods are short and are over in a few days. In heated rooms, the flies will die, but on ceilings and in small cracks and crevices, the very cold-tolerant flies will overwinter. The flies like to visit the same buildings year after year.
Damage
Residents with surrounding grasslands will often find that they are visited by the yellow swarming fly in early autumn. Especially in properties located on the upper floors of tall houses and buildings. But the yellow swarming fly also has a particular tendency to visit – or invade – houses covered with ivy or wild wine. The reason for this is presumably because such areas can constitute ideal natural wintering sites for the grass fly.
However, there is no reason to move heaven and earth if the yellow swarming fly should have found its way inside. They cannot cause damage inside but can at most be an annoying element. At the same time, the flies will automatically die if they come inside. They cannot overwinter in heated rooms and therefore die on their own after a short time.
It is different outside. Here, the yellow swarming fly can survive temperatures down to minus 30 ° C if they stay in a protected area.
Prevention and pest control
As described, the grass fly does not pose any harm to humans or crops. Therefore, there is also no reason to prevent or control them, as for instance, spraying grass areas outside buildings with pesticides.
On the other hand, one should take his precautions during the period when the yellow swarming fly is preparing to overwinter, and one should therefore try to prevent the flies from entering. This is best done by treating windowsills, door frames and similar areas and cracks with a spray against creeping and crawling insects that contain permethrin.
Flies that have already entered the home are controlled with ordinary insect or fly spray or removed with a vacuum cleaner.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)