Cala D'or is a lovely place to take little ones - we return year after year! (have 5 year old) - You may get the odd mozzie, my mum always seems to get bitten at least once, but nothing really to speak of. Avoid Alcudia for the mozzie's - we tried it for a change - I looked like I had a disease I was bit soo much! Never again!

i agree,Cala D"or is a lovely place.There are a few beaches to choose from,all nice and clean.It is a great choice for families with young children,there is plenty to do and see,without the rowdiness of the more youngster orientated parts.There are some lovely hotels also

Cala dor is a fab place for children, there is not the risk or running into the typical hooligans over there.
regarding the mozzi problem, here is some great advice.

A really cheap and effective method is to apply lemon juice to your skin, you know the jif ones that you can buy in the yellow lemon shaped bottle. this does not smell, it is not sticky and is cheap!
The reason that mosquitos bite is the attracting smell and taste of the skin, therefore if you apply a bad tasting cover to the skin they will reject this and find someone else to bite! Normally the mosquitos come out during the evening, normally after sunset etc, so make sure you buy a liquid plug for your room and turn this on when you leave for dinner, leave a window or shutter open so that they can fly out, these plugs do not kill the insects they repell them, so they need an escape route as such.
Make sure that you buy an antihistime cream in Mallorca for the bites as the composition is more effective for the insects here rather than the uk, be careful taking any tablets and drinking as this is similiar to overdosing.
I am sure you will be fine and make sure you don't scratch any bites as they will scar.

Regards

can't help you with the mozzie situation - we believe there is a whole world to go and see,and why go anywhere twice - we went last year for the first time to cala d'or and it was so lovely we are returning this year