The antennae are the butterfly’s nose, with which it can sniff out flowers with nectar and the right mate. They are also its clock and compass. From the position of the sun in the sky they tell both what “time” it is and make sure the butterfly flies in the direction it wants. This also applies on long journeys if it is a migrant.
At the base of the antennae is an organ (Johnston’s organ) that works as a gyroscope and controls balance, for example in windy weather.
As a rule, butterflies (ex. 3) have straight, smooth, club-shaped antennae, and moths have pointed antennae (ex. 1 and 2). In some moth species the male has hairy, feather-like antennae (ex. 2), which make it easier to track down the female for mating.
Sooty Copper – with thread-like antennae ending in a club – typical of butterflies
Antler Moth – moth – male with clearly feathered, pointed antennae
Skippers – butterflies – differ slightly from the norm, as their antenna tips are angled
Drinker – moth – male with extra-broad antennae to track down the female more easily
Egelanghornsmøl (a longhorn moth) – moth – with extra-long antennae
The burnet family, which are moths, is an exception to the general rule. As their Danish name suggests, they have club-shaped antennae, as can be seen in the photo of the Transparent Burnet.