The latest was in Pound Lane, Upper Beeding, last week.
The victims were in the rear garden and had left a side door open.
Someone entered the house and stole a jewellery box.
Other incidents have been reported in the Worthing area.
Police advice is:
If you leave your house empty – even when you are in the back garden – lock all the doors and windows and make sure fanlight windows are closed. Be especially careful about those on the ground floor and above flat roof areas.
When you leave a room unattended, close the windows and doors – especially on the ground floor.
Keep all wallets, purses, credit cards and car keys out of sight. If you want to leave your windows open while you are asleep, have window restrictors fitted to stop people climbing in.
Double check fences and boundaries to make sure they keep burglars out.
Secure garden tools and ladders in a locked shed or garage to prevent them being used to break in to your or a neighbour’s home.
Consider laying gravel on your footpaths or driveway, which can deter burglars from approaching your property.
Fit outside security lighting and a visible burglar alarm to help deter burglars.
The best defence against burglary is prevention.