To attract hoverflies I grow lilies, or on a bad year, I may have to resort to buying them from the florist. Make sure that the flowers still have their stamens, as these are essential for keeping the flies interested, some flower shops remove the stamens.

I use a 100mm macro lens usually fitted with a (typically 21mm) extension tube. I prefer to shoot in full sunlight and use a ring flash to provide fill lighting.

The key ingredient for photographing hoverflies is patience as the attrition rate is painfully high. The difficulty is in getting accurate focus and sufficient depth of field, 10% technique and 90% luck.