If you see a patch of tree bark that appears to be crawling, you have probably met Cerastipsocus. These are barklice (order Psocodea, family Psocidae), small insects that gather in conspicuous, slow-moving herds on trunks and branches.
The comparison to cattle is not far off. The common name tree cattle comes from the way they graze: the whole group moves together across the bark, scraping up algae, lichen and fungi as a mobile lawnmower crew.
At least 20 described species belong to the genus, and they are completely harmless to humans. This herd on Rinjani was doing exactly what barklice do best: turning a boring trunk into a busy little pasture.
What is the order of this insect?
Great question! Cerastipsocus belongs to the order Psocodea (barklice, booklice, and their relatives). In older literature you may see these insects placed in the order Psocoptera, but modern classification treats the barklice as part of Psocodea, which also includes the parasitic lice. More specifically, this genus sits in the family Psocidae. The ‘tree cattle’ on this post are the barklice subgroup, and GBIF lists Cerastipsocus under Psocodea, family Psocidae.
这个昆虫吃什么？
它们吃的是树皮表面的藻类、地衣和真菌。一整群像放牧一样在树干上慢慢移动,边走边刮食这些微生物,所以英文名叫 tree cattle(树牛)。文章里 Rinjani 那棵树上的这群就是在干这个。它们对树和人完全无害,更像是树干上的小清洁工。