Sharon,whatever you do,remove the ivy from the tree.You can do this by using
a hand pruner,and cut the ivy down as close to the base of the trunk as
possible.Once the ivy is cut,the remaining ivy on the tree will die and fall
off.The ivy can choke the life out of the tree.In winter if you have an ice
storm,the ivy can freeze and the weight of it can actually bring down limbs
or the whole tree,I have seen that happen too many times.
All I know about mosquitoes is that I hate them.Good Luck!