There are multiple metric units to choose from! This tutorial goes through the process of choosing the best metric unit to use for measuring the mass of a given object.
The most common aphids on houseplants are the light green ones (pear aphids), but aphids can also be found colored pink, white, grey and black. Additionally, winged aphids can appear when colonies are established and fly to infect new plants. Juvenile aphids (nymphs) look like smaller versions of the adults.
The adult pinworms are white and measure less than one half inch long, with the diameter of a strand of thread. These tiny roundworms are quite complex. Like us, they have mouths, throats, and gastrointestinal tracts. Like us they have nervous systems. The females have a vagina, a uterus, and ovaries.