Latin: Psychodidae
The Butterfly mosquitoes go by several names, drain flies, sink flies, filter flies, sewer flies or sewer gnats and in Latin Psychodidae. They are often noticed when they fly around in the bathroom.
Appearance
The butterfly mosquitoes can be confused with moths because of the extremely hairy wings. To distinguish them from one another the moths only have a single pair of wings, which is the opposite of butterfly mosquitoes. In addition, the butterfly mosquito is small only two to three mm long.
Color wise, the adult butterfly mosquito is greyish, and the larvae are whitish. The larva has a dark head and a small breathing tube at the backend. Typically, only this breathing tube protrudes.
Although the butterfly mosquito is small and with relatively large wings, it is poor at flying. When it moves, this happens in a bouncing and soft manner- or simply just by wandering around. At rest, the wings are held over the body like a roof.
Biology and behavior
Butterfly mosquitoes lay up to 100 eggs. The small eggs are oval, white, and long, but measures only 0.2 mm. The indoor species of the butterfly mosquitoes, Psychoda, usually lay all their eggs in sludge that end up in drains, and water traps in areas like the bathrooms.
Sludge is an obvious place for eggs and butterfly mosquito larvae, as it is always moist without being directly covered with water. In addition, there are fungi, algae, bacteria, and decayed organic material in sludge, which the larvae nourish on. The development from egg to larva to adult butterfly mosquito usually takes one to three weeks.
If they are instead outdoor species of butterfly mosquitoes, they live in sludge basins, filters, manure, lakes, and streams. Especially at sewage treatment plants, the number of butterfly mosquitoes is large, which is precisely due to the good living conditions for the mosquitoes.
Damage
In Denmark, butterfly mosquitoes are not harmful. They do not sting and does not inflict any damage to humans or buildings. They are in fact useful in converting organic matter in filters at sewage treatment plants. In large numbers they can however be annoying.
In subtropical and tropical regions, it is a completely different story. Here there are members of the butterfly mosquito family which bites. And not only are they very annoying, but they are also able to transmit serious diseases. If you are in a foreign country, you should be more careful regarding the butterfly mosquitoes in relation to the Danish types.
Prevention and control
Although butterfly mosquitoes in Denmark are not harmful, they can still be a nuisance. If you wish to prevent the appearance of butterfly mosquitoes, you should clean your bathroom drain on a regular basis.
If they appear in great numbers, they can be controlled by removing the sludge, in which the larvae are living. It is necessary to remove the sludge manually. Either by rinsing or by using a brush. Then rinse with drain-cleaner or boiling water, which soda may be added to. Be aware that sludge can accumulate in the overflow of the sink.
If it is not possible to clean toughly, the adult butterfly mosquitos can be controlled in other ways. You can use an insecticide for flying insects. Spray the room daily for a period, to kill all the newly hatched butterfly mosquitoes. In this way they will not have time to lay new eggs and the occurrence will stop. Remember to follow the instructions on the insecticide carefully, so that you are using the product correctly.
If the source for their appearance is outside, you can only solve the problem by finding the place of origin. Suspect all kinds of places with manure and sludge in this case and carry out a treatment that is aimed at the specific conditions.
"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)