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.
It is a serious pest, transmitting many plant mosaic diseases. The melon, or cotton, aphid (Aphis gossypii) is green to black. In warm climates live young are produced all year, while in cooler areas there is an egg stage. Among the dozens of possible hosts are melon, cotton, and cucumber.