
Large colonies of soybean aphids contain several thousand individuals per leaflet. (Marlin E. Rice)

Large colonies of soybean aphids contain several thousand individuals per leaflet. (Marlin E. Rice)
Links:
[1] http://www.ipm.iastate.edu/ipm/icm/node/114
[2] http://www.ipm.iastate.edu/ipm/icm/2006/1-23/thresholds.html