Would you raise the baby that ate your siblings? - Francesca Barbero
You might not guess it,
but this Alcon blue butterfly
is a parasite whose offspring
will live highly unusual lives.
She lays pinhead-sized eggs
on a wildflower and is off.
The first tiny caterpillar
hatches a few days later.
After two weeks living
within a flower bud,
he embarks on a high-risk operation
that will require infiltrating
a densely guarded fortress undercover.
He secretes a thread of silk
and descends to the ground.
Here, he's more vulnerable than ever,
but he holds still and waits.
His descent perfectly coincides
with the peak foraging hours
of the nearby red ant colony.
Soon enough, a worker ant
encounters the caterpillar.
She inspects his cuticle
with her sensitive antennae
and picks up on key chemical cues
that she uses to recognize her kin.
This is all part of the
caterpillar's disguise.
The worker picks him up
and reverses course.
Indeed, the caterpillar doesn't battle
his way into the fortress.
No— he wouldn't stand a chance.
He's shepherded in because the ant
is treating him like one
of her colony's own larvae.
They pass legions of ants
poised to attack invaders
and enter the intricately architected,
subterranean nest,
which is sheltered, moist,
and stockpiled with resources.
If the caterpillar's mimicry didn't work,
he might have been left for dead
or taken as food himself.
Instead, the ant places the caterpillar
in the nursery,
among the colony's own cherished brood.
Here, he produces sugary secretions
that the worker ants feed from.
The nurse ants dote upon him,
regurgitating food
into his mouth frequently.
But he has a voracious appetite.
He arches his body in a begging
posture to obtain more food,
and, every now and then,
eats one of his own nestmates.
The caterpillar also does things
that the ant larvae can't:
he makes noises that sound a lot
like those emitted by the ant queens.
In effect, he signals that he's royalty
and should be prioritized
over the actual ant larvae.
And that's exactly what happens.
The nurse ants feed him extra.
And when a wild boar causes part
of the nest to collapse,
the ants rescue the caterpillar first.
While members of the ant colony suffer
reduced survival rates
because of the burdensome caterpillar,
he passes the harsh winter
living like royalty.
Come June, he's stored up plenty
of nutrients
to make a dramatic transformation.
He forms his chrysalis,
and for three weeks,
he uses a tooth-and-comb organ to create
more queen-like acoustic vibrations,
attracting workers to clean him.
Then, at dawn one day,
he emerges an adult butterfly.
Wings still wet, his body easily fits
through the gallery opening,
and finally,
11 months after being taken in,
he basks in the sun
and begins searching for a mate.
When he dies about a week later,
he'll have spent the vast majority
of his life in the realm of the ants.
The Alcon blue is one of as many
as 200 parasitic butterfly species,
all of which target ants.
Sometimes, multiple caterpillars inhabit
the same ant colony at once.
Some stay for almost two years.
But researchers are still parsing
these complex relationships.
For instance, certain ants guard Japanese
oakblue caterpillars from predators
and consume the sugary secretions
the caterpillars produce in return.
But it turns out that this
sweet concoction
isn't a simple form of mutual assistance.
Instead, chemicals in the secretions
actually manipulate the ants' behavior,
inhibiting their movement
and making them more protective
and aggressive caterpillar guards.
Despite these masterful manipulations,
parasitic butterflies are
vulnerable themselves.
They're also the targets of parasitism.
Even within their adopted,
high-security hideaways,
parasitoid wasps sometimes track
the caterpillars down
and lay eggs on their bodies.
When the wasp larvae hatch,
they consume the caterpillars alive.
And because their life cycles consist
of such a complex choreography
involving specific plants and ants,
small environmental changes can
affect their populations.
One parasitic butterfly species actually
went extinct in the UK in 1979,
before being reintroduced
a few years later.
They've since rebounded alongside
efforts to restore the meadow habitats
their host ants require to thrive—
helping preserve these
riveting relationships
and the astonishing adaptations
they inspire.
