Measurements of 97 workers from the same colony of Philidris th01 in Sakaerat: (a) size frequency
distribution of head width, showing bimodality; (b) length of head relative to tibia. The slopes of the regression
lines correspond to the allometry coefficients: 1 for small workers (isometry;white points and dotted line) and
1.5 for large workers (allometry, black points and solid line). Slopes are significantly different (SMA regression;
p = 0.005)