What are hoverflies?
The small flies at home in your flowers are NOT hoverflies. They are fruit flies and have their own projects and websites. In this project we are interested in genuine hoverflies, thus pollen and nectar-eating flies that often resemble bees, wasps, bumblebees and other insect pollinators, which the birds early learn are unpleasant to eat. Hoverflies mimic hymenopterans (i.e. such as bees and wasps) not only in appearance but also to some extent in behavior. This is called Batesian mimicry, where a harmless species mimics a dangerous one to avoid a common enemy. However, there are some differences. Hoverflies do not have the characteristic "waistline" that hymenopterans have, and not as sturdy legs and their eyes occupy a much larger portion of the head. The eyes are one of the ways I personally use to distinguish a hoverfly in the field from a hymenopteran, if it is a species I am not as familiar with. If you manage to capture a hoverfly you can also note that hoverflies only have two wings, unlike bees and wasps who have four. When you begin to get really good, you can soon see that flight pattern differs slightly between hoverflies and hymenopterans. Eg bumblebees fly very heavy and also land very heavy, while the hoverflies that imitate them often have a "lighter" way of flying. Hoverflies, in my opinion, often fly very gracefully, a little like as if hoverflies were figure skaters and hymenopterans were hockey players. Another comparison of behavior is that bees often creep into the flowers they visit while hoverflies move much more superficial. This has to do with bumblebees and bees having longer tongue than hoverflies, as hoverflies need to find relatively flat flowers to reach the food.
Eristalis
Eristalis are some of the largest flower flies we have in Sweden. Generally, they look like bees but with large eyes and no waist (they are much closer drone bees, males, in appearance, but it's very seldom we see drones outside the hive so the comparison is relatively meaningless in the field). They are usually dark with orange or brown patterns on the abdomen. In comparison with the bees, they are also relatively hairless and with slimmer legs. Eristalis can also sound rather bee-like for those who manage to get close enough.
Episyrphus – E.g. Marmalade fly
Marmalade flies are also one of the most common species we see in the field. They are quite small, have reddish eyes and beautiful black, fairly thin, stripes on its orange abdomen. Something that goes to note for those who are patient is that abdomens of marmalade flies can sometimes be seen as relatively transparent. In comparison to Eristalis, the marmalade flies are also more elongated and sounds much less.
Sphaerophoria
Sphaerophoria has a very narrow abdomen, especially the males. The females have a slightly more pointed abdomen, but remains narrower than the abdomen of a marmalade fly, which are otherwise similar in size. Sphaerophoria have thicker black lines on their abdomens than marmalade flies and in many males the last segments are very orange. They also often have a darker eye color than the marmalade flies.
Syrphus
In our list, the Syrphus are in the middle in size. They have wider abdomen than marmalade flies, and are proportionally more like Eristalis since they are not so long and narrow, but have a slightly wider abdomen. They have similar eye color as marmalade flies. The abdomen is yellow with thick black lines.
Text: Malin Thyselius
Eristalis
Eristalis are some of the largest flower flies we have in Sweden. Generally, they look like bees but with large eyes and no waist (they are much closer drone bees, males, in appearance, but it's very seldom we see drones outside the hive so the comparison is relatively meaningless in the field). They are usually dark with orange or brown patterns on the abdomen. In comparison with the bees, they are also relatively hairless and with slimmer legs. Eristalis can also sound rather bee-like for those who manage to get close enough.
Episyrphus – E.g. Marmalade fly
Marmalade flies are also one of the most common species we see in the field. They are quite small, have reddish eyes and beautiful black, fairly thin, stripes on its orange abdomen. Something that goes to note for those who are patient is that abdomens of marmalade flies can sometimes be seen as relatively transparent. In comparison to Eristalis, the marmalade flies are also more elongated and sounds much less.
Sphaerophoria
Sphaerophoria has a very narrow abdomen, especially the males. The females have a slightly more pointed abdomen, but remains narrower than the abdomen of a marmalade fly, which are otherwise similar in size. Sphaerophoria have thicker black lines on their abdomens than marmalade flies and in many males the last segments are very orange. They also often have a darker eye color than the marmalade flies.
Syrphus
In our list, the Syrphus are in the middle in size. They have wider abdomen than marmalade flies, and are proportionally more like Eristalis since they are not so long and narrow, but have a slightly wider abdomen. They have similar eye color as marmalade flies. The abdomen is yellow with thick black lines.
Text: Malin Thyselius