In the last 3 weeks i have noticed these bluebottles covering my wall. They only appear when the sun is shining on this wall. My neighbour removed ivy which was covered in these insects, She assures me her bins have nothing untoward in them.. We have removed everything from the area but still they are appearing.Is there an epidemic at the moment. There is nothing dead in the garden.my garden is small and i cannot enjoy it at the moment. Please help?