Aphids, what the heck are aphids?

I have written about aphids before, but never dedicated a post to them. Aphids are in the insect order Hemiptera. Aphids feed almost exclusively on plants so they fall solidly under the category of pests in the garden. 

Annoying as they may be to gardeners and farmers, aphids are very interesting creatures. 

Aphids often live in colonies where the mother or fundatrix gives live birth to many genetically identical offspring. Most of the time they are just feeding on the phloem (AKA sap) of plants, which is where they get most of their nutrients. 

Individual aphids are fairly sedentary creatures, but every once in a while, the colony produces winged aphids that go off in search of new food plants. Ants will also sometimes carry aphids to new plants (e.g. see this article about the corn root aphid). Ants and aphids sometimes form a symbiotic relationship where the ants protect the aphids from predators and the aphids provide the ants with honeydew. The aphids secrete honeydew as a byproduct of their feeding on the carbohydrate rich but nutrient poor plant sap. For the ants, the honeydew is an important source of carbohydrates (sugars). 

If you have ants tending aphid on a plant in your garden, one solution is to create a sticky barrier around the stem of the plant. This will prevent the ants from protecting the aphids, and the aphids' natural enemies will be able to attack them. Aphids have many natural enemies, including lacewing larvae, lady beetles, and parasitoid wasps.