SIG mosquito is actually a semi-automatic pistol manufactured by the Swiss/German company SIG SAUER. It is sometimes called simply Mosquito, SigArms Mosquito or SigSauer Mosquito Pistol.
Sig Mosquito is based on the Sig Sauer P226 chambered for the .22 Long Rifle Cartridge and is said to be the ideal choice for hours of shooting fun. The Sig Sauer Mosquito pistol is equipped with a wear-resistant polymer frame set with an included Pica tinny rail.
Here are some of the specifications:
Overall Length 7.20 inches
Overall Height 5.28 inches
Overall Width 1.46 inches
Weight w/ Mag 24.6 oz
Mag Capacity 10 Rounds
It would be really interesting to know how the gun got its name, but this is a hard task, I guess. I keep wondering why people give "mosquito" names to such things as guns, songs, toys or similar even when there is not direct resemblance with e.g. the sound of true mosquito. Any ideas?