Y: Don, would you like a glass of milk?
D: Sure, Yaël, thanks.
Y: Did you know that there is a cockroach species in Hawaii called the Pacific beetle cockroach that gives milk?
D: But Yaël, only mammals produce milk.
Y: The Pacific beetle cockroach is a bit like a mammal because it gives birth to live young. That makes it rather unusual among insects, because most of them reproduce by laying eggs. Researchers discovered that the Pacific beetle cockroach's brood sac secretes a nutritious protein and carbohydrate substance to feed its babies, just like mammal mothers secrete milk. Fossil evidence even indicates it evolved around the same time.
D: This sounds like a case of evolutionary convergence, where evolution finds a similar solution to a similar problem in two very different groups of animals. But this substance can't really be much like milk, can it?
Y: It's surprisingly similar. A team of scientists published an analysis in 2016. Cockroach milk contains many of the same substances found in breast milk, including the sugar mannose. It is very rich in protein, and has three times the caloric energy of buffalo milk. It is a complete food with all essential nutrients, and the nutrients are time‑released. Because it uses protein instead of fat as a binding agent, it doesn't spoil or need refrigeration.
D: From all the benefits you are mentioning, it sounds almost like scientists think we should...YUCK!!!... drink it...Bleh!
Y: You guessed right. Researchers want to put the genes for making cockroach milk into yeast cells, so they can make lots of it for possible use as a food supplement. Don, why aren't you drinking your milk? You don't look so good. You're green. Don...are you OK?