Last week the question was: What is this on the underside of this cotton leaf?
These are whiteflies. Whiteflies are similar to aphids in that they are piercing/sucking insects and feed on the sap within plants. They excrete honeydew as they feed, also like aphids. If populations are high, feeding damage can cause wilting and stunting of the plants. Whiteflies are rarely a problem in cotton because natural enemies do a good job of controlling them. For more info, take a look at pages 102 and 113 of the SC Pest Management Handbook.
Here is this week’s question: Which caterpillar is feeding on this soybean leaf?