from the takes-something-like-this dept.
Not all caterpillars grow up to be beautiful butterflies. Some become living milkshakes for their dads, who guzzle caterpillar body fluids to attract the ladies.
Recently, scientists reported the first evidence of butterflies sipping from the bodies of caterpillars — dead and alive. They observed adult milkweed butterflies in North Sulawesi, Indonesia, using tiny claws on their feet to scratch wounds in caterpillars' bodies so they could lap the liquid that oozed out.
Male butterflies seek certain compounds produced by milkweed (flowering plants in the family Apocynaceae), which repel predators and help the butterflies produce pheromones that attract females. Since caterpillars are stuffed with juices from chewed-up plants, they make an easy target for butterflies looking to chemically boost their attractiveness to females.
[...] "The caterpillar larvae would contort their bodies rapidly in what appeared to be futile attempts to deter the persistent scratching of adults," said the researchers who observed the butterfly baby-drinking. They described their observations in a study published Sept. 8 in the journal Ecology.
Butterflies in the Danainae family are known as milkweed butterflies because most of the caterpillars in this group feed on milkweed plants, which contain toxic alkaloids that are absorbed by the caterpillars and then processed into useful chemicals that protect them from predators. Another use for these alkaloids is in mating pheromones, which are transferred to females in the males' sperm packet "as a nuptial gift," the scientists wrote.
Yi-Kai Tea, Jonathan Soong Wei, Ethan P. Beaver, et al. Kleptopharmacophagy? Milkweed butterflies scratch and imbibe from Apocynaceae‐feeding caterpillars, Ecology (DOI: 10.1002/ecy.3532)