The majority of insect induce galls are due to Aphidae infestation. The case is same in Terminalia, but Pater rightly said please put some picture by which anybody could identified this pest
Could be a psyllid Trioza fletcheri minor (Hemiptera: Psyllidae)? You can see more datail about this insect on: http://rameau.snv.jussieu.fr/cgi-bin/psyllesexplorer.pl?db=psylles&card=searching&lang=en. If you have photos, could you please send to me? Thanks