Chevrons on USMC shirts

[Sgt. John McAfferty]

Howdy All,
My question concerns chevrons on the blue fatigue shirts worn by the Marines until they replaced it with khaki.  In several b/w photos it is apparent chevrons were sewn on these shirts although that was not regulation.  I have determined this was done in the tropic areas where wearing the blouse on campaign was inadvisable.  My question is, how large were they and what color?  It doesn't seem from the photos that they took the large chevrons found on blues.  My thought is they had smaller chevrons locally made but I can't find anything.  Any help is appreciated.