Alate: 11.75–12.00 mm long with wings; 5.25–5.50 mm without wings. 

Larger than but indistinguishable from N. fumigatus

Worker:  4.25–4.75 mm in length.

1. The head is mainly brownish-yellow or ochre.
2. Antennae of 14 segments; 4th segment is the shortest. 
3. Postclypeus about half as long as wide.

Soldier: 3.70–4.10 mm in length.

1. The same colour as N. fumigatus, but differs in size since N. ooccasus is larger.
2. N. ooccasus has a thicker and larger rostrum than N. fumigatus and a differently shaped head. 
3. Mandibles have points.