I was playing in a park when I noticed a tree was moving!!! When I looked closer it was full of black butterflies with orange spots on the tips of their wings! Quite strange, anyone know why?
on the main inaturalist.org site (or app), you should make an observation of the tree, and make another observation of the butterflies. once you identify what kind of tree and what kind of butterfly, you’ll be able to do a little research to find out if there are any known relationships between the two. the butterfly might be using the tree as a host, they might be feeding from flowers, or they might be just taking shelter in that tree while on the move.
Butterflies are attracted to the flowers normally when they absorb nectar from them. But sometimes migrating butterflies rest on trees in large number when they are tired of flying at take a break. Otherwise some of the butterflies gather together in large number on milkweed to drink the sticky latex (which is source protective chemicals for them). They do so on the flowers of the same trees as well, but the numbers are usually <10-20. Another behavior where butterflies of same or different species gather together in large numbers is when they are puddling. Butterflies (Mainly males) need sodium ions, which they absorb from mud. Congregations of >50 butterflies of same or 2-3 different species can be seen near ponds/waterfalls in summer when there is mud-puddling going on.
Hope that answers your query :)
Gaurav (@gs5 on iNaturalist)
Butterfly group roosting is a strategy of preventing predation. Various species may roost in groups. There are articles on it.
You should really upload an observation of this. There are many reasons why Lepidoptera aggregate. Some may act as migratory/overwintering spots, as is the case with Monarchs and overwintering Euploea spp. in Hong Kong and Taiwan etc. In Hong Kong there is a plant called Crotalaria which often attracts large numbers of Danainae spp. who feed on the “juices” to collect poisons.