I found the stump of a chestnut tree (kuri) and all of its few remaining branches were covered by a huge colony (huge colonies?) of chestnut aphids (kuri-oo-aburamushi).
It was interesting to see the variety of forms all mixed up in the colony: small red eggs, nymphs, large black viviparous females, and both male and female winged forms.
In the next photo, you can see the defense strategy these aphids use – they all raise their hind legs in the air and shake them vigorously. It surprised me, so I guess it might scare away a bird!
Hemiptera: Homoptera: Aphidae
Great Chestnut Aphid = kuri-oo-aburamushi
Location: Edge of mikan orange orchard near Munakata Common (map).