Before the long winter in Hokkaido, "snow bugs" are often seen in autumn. In Hokkaido, it is said that "when snow bugs fly, the first snow will fall," but "snow bugs" is not an official name. What exactly are they? We also looked into whether it is really true that "when snow bugs fly, the first snow will fall."

The true identity of snow bugs is the "Todononeowatamushi"

What is called "snow bug" is actually a type of aphid called "Todononeowatamushi". When they reach adulthood, they are covered in waxy white fluff and fly around lightly, which is why they got the name "snow bug" and mean "snow bug".

The Japanese ash aphids are born in spring on a tree called Japanese ash, and take up residence in Japanese ash from summer to the beginning of autumn. They suck sap from the Japanese ash trees and produce several generations over the course of a year, and at the end of autumn the winged adults migrate to the Japanese ash. In other words, what we see as snow bugs is the adult Japanese ash aphids in the process of migrating from the Japanese ash to the Japanese ash.

A unique survival strategy unique to weak insects

The Japanese aphid is known as a "weak insect" and has no way to fight off predators, so it is quickly eaten. However, a major feature that helps it resist predation is the presence of a morphology called a "stem mother."

As they molt repeatedly, they become females called "main mothers," who give birth to genetically identical clone female larvae, which then give birth to clones and multiply. One female gives birth to about 150 larvae, so they have survived by continuing to give birth to more than that number, even though they are preyed upon.