Mosquito bus?

I was taking 86 home from tution. The ride was pretty peaceful at first. When the bus was moving to the Seletar airport area, something black and small was flying near me. So instinct told me to kill it (a.k.a smack it lah) and then.. BLOOD!! I looked closely at my "kill", it was a mosquito! A mosquito on a BUS!! It was pretty scary. So after I became slightly paranoid. My paranoia was confirm when I saw more flying bugs near the exit of the bus. Of course, I was scared. Paranoid too! Some few near me (I was seated opposite the exit) I moved my legs so as not to be their meal. OMG. How did mosquitoes board the bus? They didn't even tapped E-Z link card. I guess probably during the turn towards Seletar after Jalan Kayu. There were some plantations there. Scary!! Oh! I took a picture of the dead bug.