In some areas of Brazil, wasp nests are offered as house warming gifts because the wasps will eat the mosqitoes. Lizards are sometimes offered as well to control roaches or ants (btw, I understand ants and roaches will not inhabit the same place). If you have any problems with mosqiotes, it might not be a bad idea to leave the hornet's nest (barring a loved one with severe allergies to their stings).