Mother Mosquito
     At  the  Character Selection screen, hold L1 and press Up, Right,
Left,  Down,  Square,  Square, R1, R1, R1. If done correctly, you will
hear a shout.

Father Mosquito
     At  the  Character Selection screen, hold L2 and press Up, Right,
Left,  Down,  Square,  Square, R2, R2, R2. If done correctly, you will
hear a shout.