Hi Sue,
I did this trip last October - it was fabulous! Some of the hotels had anti-mozzie plug ins in the room, I remember at Kruger they did and also in Zambia. I didn't get bitten once - not sure if this is because I was using deet and wearing special bracelets but I don't remember seeing many insects. I don't think a net would be necessary.
My top tip would be to do the microlight over Victoria Falls if you get the chance. I wasn't sure before the trip but was so glad I did, such an amazing experience. (My avatar pic is from then). Another tip would be to pack a small sunscreen in your hand luggage as we went straight from the airport to Table Mountain and could have fried in the queue otherwise.
Have a wonderful time and feel free to ask if you have further questions.