Here are complex actions I’ve seen Monarchs perform spontaneously:
caterpillar crawling DOWN the milkweed, across a distance of 10ft to 40ft, then UP an object, to turn into a chrysalis
butterfly, while eclosing, grabbing the rim of the chrysalis with front claws to hang on
caterpillar, turning into a J near a wall: orienting so that the airholes of the eventual chrysalis will face away from the wall
caterpillar, very tiny, seeing a praying mantis above it, creates a silk thread and descends to the edge of a lower leaf, then crawls under the leaf
caterpillar, being stung by an ant in its tail area, turning its head and body to grab the ant with its mouth and throw the ant away
caterpillar moving to underside of a leaf to shelter from direct sunlight
butterfly, female, tucking under the male while mating in flight
caterpillar crawling on the edge of a leaf
caterpillar chewing a leaf a section at a time
caterpillar stops chewing a milkweed leaf when an animal is nearby
caterpillar curling into a ball when disturbed and playing dead for a few minutes
butterfly, climbing up a human finger, said finger held nail-first toward the butterfly’s head
butterfly, male, chasing a female butterfly
butterfly, female, evading a male butterfly
butterfly, female, laying eggs on the underside of a leaf, despite a human trimming the milkweed plant
butterfly, newly emerged, setting out on the species migration route, to a place it has never been
butterfly, newly emerged, hanging upside down from the chrysalis for several hours while its wings unfold below it
As the ‘hanging J’ phase ends, the caterpillar splits and the chrysalis emerges, the chrysalis rotates clockwise five times, then counterclockwise five times, and continues to alternate until the husk of skin finally falls away.
The mature caterpillar always tries to crawl away from the milkweed plant. It will crawl a certain distance and begin anchoring itself under an object and then becomes a hanging J. If confined in a cage, the mature caterpillar will crawl the equivalent distance around and around in the cage, then finally go to the top of the cage and begin turning into a hanging J. It seems that the mature caterpillar is compelled to crawl a certain distance. The advantage of this may be to disassociate itself from a milkweed that no longer has much concealing foliage.
A small caterpillar, placed on a leaf, will usually begin crawling toward the stalk.