Hoverflies, unlike many other families of flying insects, enjoy a fairly good relationship with humans. This is in spite of the fact that many species practice mimicry and resemble wasps or bees. The sight of a hoverfly, hanging suspended above a flower, seems redolent of warm, summer days, with the still air full of drowsy buzzing. Hovering in still air requires a high expenditure of energy, and hoverflies visit flowers, primarily, to feed on nectar or, in some cases, pollen. Nectar consists largely of sugar and water, and many species of animals rely on it as a food source. Some hoverflies display a preference for a certain species of plant, and the golden hoverfly seems to favour ivy. A number of similar insects feed from ivy as well, and it can be difficult to distinguish them from visiting wasps and hornets.
Male hoverflies visit flowers for other purposes, too. They may be looking for females and it is thought that courtship flights take place, with the males hoping to mate. Having mated, female golden hoverflies search for trees in which to lay their eggs. They usually choose live, standing beech and ash trees, which have lost a branch and, through the activities of fungus and bacteria, developed a rot hole. A number of different types of animals use these rot holes, including birds such as owls, and they are an important part of the woodland ecology.
Hoverfly larvae are unusual among other insect grubs in having a 'tail', which consists of two fused breathing tubes. In most cases, such as with the golden hoverfly, this tail is short, but a few species that lay their eggs in water have larvae that have breathing apparatus several centimetres in length. These breathing tubes are vital to the grubs as the interiors of rot holes are frequently wet. The golden hoverfly larvae take two years to reach the pupation stage in their life-cycle. The adult flies emerge in September or October, unlike most other hoverflies which are on the wing in spring and summer. Just before hatching, the pupa moves to a drier part of the rot hole so the emerging adult hoverfly avoids getting wet. Tree holes can provide food and accommodation for many generations of hoverflies, so it is important to retain these features within a wood. All too frequently, trees which show signs of rot are removed by woodland managers.