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.
If your morning glory's leaves are wilting, insects may be attacking the plant. One pest that attacks morning glories is the cotton aphid, a species of insect that ranges in color from yellow to nearly black. Look for a mass of aphids on the leaves and leaf crinkling. The leafminer is another possible culprit.