Why are abdomens of certain species more greasy than others?

[lordpandarus]

Spread a few Junonia species from Africa. J.cuama,antilope and cebrene

All had big grease stains on hind wings and needed an acetone bath

I rarely see this on any butterflies. Only other one I see this a lot is Speyeria diana

[africaone]

grease is a stock of energy. It is most develloped in species that feed few or not (as saturniidae) during their lifetime.

[lordpandarus]

I can understand for big moths but why the Junonia (Precis) with tiny abdomens specifically? They seem like random small butterflies