How Do Butterflies Date?
For most butterflies, finding a mate to share their short lives with is their most important
mission. To meet 'the one' among a swathe of unsuitable or unwilling partners, butterflies
must adopt clever tactics.
One of the easiest ways for butterflies to find a mate is by being as colorful as possible
— a technique these insects don't need to think about. Butterflies that fly in the day
can afford to rely heavily on colors, and their displays range from delicate pastels to
iridescent blues. Colored wings are a signal to other butterflies. They allow butterflies
to recognize their own species in a complicated habitat. Colours also distinguish between
males and females — vital when you are looking for a partner.
Pastel colors in butterfly wings are caused by chemicals called pigments. They absorb
certain wavelengths of light and reflect others, causing the eye to see a particular color.
Bright, iridescent colors are produced by the structure of the wing itself. Some species,
such as the Blue Morpho, have wings that are made up of millions of tiny scales. The scales
reflect light waves repeatedly, creating a very intense color which can appear to move with
Colors are useless in the dark, so butterflies that fly at night use acoustic and chemical
signaling to reach out to others. Both males and females give off scent to communicate
with each other, releasing specific pheromones to attract the right type of mate.
During the first stages of finding a partner, males optimistically chase after almost any small,
moving object. This includes leaves, bees, and butterflies of any species — of either sex.
When they get closer, they can start working out if they’ve found the right match, by judging
colours, pheromones and behavior.
Some female hormones are so powerful that a male butterfly can sense them up to 10 miles away.
Male butterflies can create acoustic signals or pulses to let females know they are searching
for a perfect match. These pulses have the added benefit of sounding threatening to other males,
as they mimic the noises bats make when they hunt.
Evolution always tries to save energy, so lots of these signals work in two ways — both
attracting a mate and sending away the competition.
One of the most intriguing behavior to witness can be that of courtship. Each species of butterfly
has their own display or 'dance', which may be performed by both sexes or just the male. These
courtship displays help to ensure that butterflies mate with their own species, and communicate
receptivity. Think of it as the first date for butterflies to begin to get to know each other.
Once a pair of potential lovers has found each other, the courtship can start. Initially butterflies
find each other using color and sound. But at this stage a decision is made about whether to
mate based on the pheromones that both sexes give out.
In many species, the female requires the male to perform a dance before she will allow him near.
He delicately flies around her, whirring his wings in the hope that more pheromones waft in her
If she is impressed enough to accept, she will change her posture, letting the abdomen protrude
from between her wings.
In many butterfly species, females mate only when they first emerge. This is why males tend to
emerge a few days ahead of females. After mating, females then try to avoid the unwarranted
attentions of amorous males while they get on with the important task of egg-laying.
In monarchs, breeding season individuals are sexually mature 4-5 days after they emerge as
adults, and the generation that migrates is not sexually mature until after the overwintering
period. When monarchs mate, the male uses the claspers on the end of his abdomen to attach
to the vaginal groove (ostium bursa) of the female. Once attached, the female cannot get away
and the male transfers spermatophore components to the female in a process that can take
up to 16 hours.
The spermatophore, a package of sperm and nutrients the female needs to produce and lay eggs.
Some males collect specific nutrients to produce a better spermatophore in an attempt to attract
The female stores the sperm in a sac called a bursa until she's ready to lay her eggs. She fertilizes
her eggs as she lays them, using the last sperm she received first.
Butterflies and Moths of North America
Southern Wisconsin Butterfly Assn (NABA)
The Butterfly Site