Aphids in a Swiss chard seed crop. Note the blackened stems and leaves as a result of sooty mold fungi growing on the honeydew exudate (sugary, sticky exudate) produced by the aphids.

Aphids in a Swiss chard seed crop. Note the blackened stems and leaves as a result of sooty mold fungi growing on the honeydew exudate (sugary, sticky exudate) produced by the aphids.

Photo Source: Lindsey du Toit, Washington State University