Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Eristalis arbustorum is a European species of hoverfly. The size of the coloured patches on the abdomen varies with larval rearing temperature, as does wing length. They are attracted to the flowers of cow parsley, hogweed, creeping thistle and knapweed.Hoverflies, sometimes called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams.