Scale

Scale insects feed by sucking plant juices, and some may inject toxic saliva into plants.  Most scale species are one of two types, armored or soft.  Armored scale is less than 1/8 inch long and has a plate like shell.  Soft scale are 1/4 inch or smaller.  Scale are also honeydew excreters.  Soft scale have several annual generations which overlap so that multiple life stages are usually present at once.  High infestations can kill a plant rather rapidly.