Alates. Alates are 16.00–20.00 mm in length with wings, and 8.00–9.50 mm without  wings. This species is closely related to N. graveolus in form, but N. walkeri is a little bigger and sometimes darker, with distinctly longer wings. 

Soldiers. Soldiers are 5.00–7.00 mm in size. They are similar to N. graveolus soldiers in form but compared to N. graveolus soldiers, N. walkeri soldiers are larger in size and  the snout is noticeably longer and wider at the base. The sizes of soldiers are variable. The heads have many hairs of unequal lengths. Mandibles have long points.

Workers. Workers are 6.00-6.25 mm in length.

1. Vertex is reddish brown to chestnut brown 
2. Sides of head, frons and postclypeus yellowish
3. Labrum paler than postclypeus
4. Antennae of 14 segments, 3rd segment longer than 2nd and 5th; 4th segment shortes of all
5. Postclypeus less than half as long as it is wide