Years ago, I found a small animal nest made of mud on the corner of the balcony. After several observations, I didn't see any animals coming in or out. I thought to myself, probably an old home that has been abandoned.
Last August (2020), another identical nest was found on the undersurface of a Pachira aquatica (Malabar chestnut) leaf. After several observations, I still didn't see any animals coming in or out. I thought to myself, it's weird, why not use the newly built nest?
I didn't understand until one evening I found a small wasp sneaking in. I suddenly realized that this is the house of a solitary wasp. She went out to work in the morning and went home to sleep before dark. It's no wonder that I couldn't see her during the day before, and I mistakenly thought this was an old home that someone didn't want.
References / 參考文獻：
1. Taxonomic studies on potter wasps (Hymenoptera: Vespidae: Eumeninae) of south India. Zootaxa. 2016 Sep 26;4171(1):1-50. (PDF)