The first time that I took a picture of a Delta pyriforme was in July last year at a park near my home. It was feeding on the clustered flowers of the Feather Cockscomb (Celosia argentea). As a solitary wasp, it operates alone versus social wasps that prefer large gathering especially when constructing their nest. Social wasps are usually more dangerous than their solitary counterpart simply because if they attack, they do in swamp. For solitary wasps, you just need to deal with one individual.

Last Sunday, I witnessed the nest building of a wasp just at my doorstep, on the slender stem of one of my potted plant, a miniature version of the Goodluck Plant (Cordyline fruticosa). The whole construction that started at around 9 am took around 3 hours to complete. I did not sit through the whole session but went in and out of my front door to monitor the progress.

When I viewed the nest at around 5 pm on the same day, something greenish was inside the nest which also blocked the entrance of the nest. It looked like a caterpillar. This wasp is known to prey on caterpillars. I would not be surprised if it was really a caterpillar which the wasp had prepared as food for its future new born.

By 7 pm, the nest was invaded by the ants that colonised my potted plant area. Ants can be seen guarding the entrance of the nest. I am not aware of any symbiotic relationship between ants and wasp's lava. Hence, this case was likely to be an invasion rather than protection. The greenish object that I saw in the nest about 2 hours ago had disappeared.

After watching the nest for a whole week, I did not see any further action.