Root aphids are a serious problem and they are not easy to get rid of. A serious infection occurred in a controlled indoor plant nursery. We never discovered how the infection began. No outdoor plants were ever admitted except as bare cuttings that were first quarantined; new plants were started in synthetic planting mixes and only sterile planting mixes were used. Nevertheless, the very agile hard coated black insect, 1/16" in length, invaded the rooting medium and could be seen scurrying into hiding. It was identified as an aphid, but I thought looked more like a beetle.
Three ingredients were used to eliminate the insect under the "zero tolerance" policy of the nursery.
Liquid pyrethrum concentrate was mixed into the water/nutrient mix. Pyrethrum is an organic pesticide refined from flowers in the chrysanthemum family. There are a number of brands available in nurseries and garden shops but you may have to go online to find a liquid concentrate.
Botanigard is a specific virulent species of fungus that infects soft-bodied insects. When a possible host insect brushes against the fungus spore, the spore attaches itself to the insect. Then it grows hyphae, which are simple thread-like filaments, into the body of the insect and starts feeding on the insect. When the insect dies it releases more fungus spores that are ready to germinate when they come in contact with a suitable host such as another root aphid. It is available at a few shops and online.
Beneficial nematodes are microscopic carnivores that attack all kinds of insects in all stages of growth. Once the nematodes come in contact with the insect, whether adult or pupae, it is walking dead. After the feast, the nematodes do just what you'd expect, so thousands more hungry nematodes enter the scene looking for a good meal. They are available in both garden shops and on the internet.
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