Massive Amount of Aphids on Lupine #651362

Asked June 15, 2020, 4:11 PM EDT

Assuming these are actually aphids - there are some lady bugs here too - and I definitely do not want to kill them these are on a native lupine - and I would be okay with pulling it out if necessary. How do I safely get rid of them without harming the other bugs?

Linn County Oregon

Expert Response

You have a few options available to you, for managing aphids on you lupine without harming beneficial insects, such as ladybugs. These options are listed, individually, but can be combined as needed or preferred.

1) Water Spray: You can try using a strong jet of water to wash the aphids off of the plant. Some will likely find their way back onto the stems, so you may need to repeat this several times.

2) 'Squish' the aphids: I prefer to manage aphids, during the early phase of an infestation, by 'squishing' them with my fingers. Yes, I know this sounds gross, but it's also oddly satisfying ~ like popping bubble wrap. Aphids release an alarm pheromone when they are attacked, and predators (like ladybugs and lacewings) and parasitoid wasps can 'smell' the pheromone. By popping aphids, you can help to locally attract more natural enemies to your aphid infestation. From the appearance of your photo, it may be too late to take this approach . . . for any reason other than the innate fun of popping aphids.

3) At the end of this growing season, you may want to consider removing the top growth from your lupines. Lupine aphids lay their eggs on the plant in the fall. When the eggs hatch in the spring, they newly hatched aphids will crawl onto any new growth. You can compost the top growth, as newly hatched lupine aphids are not able to move large distances in search of host plants. Alternatively, if the aphid infestation is really bad, you might want to remove top growth, now, and compost your plants.

4) Tolerance is also an option. I like to say that aphids are the Skittles(TM) of the insect world. They're phloem feeders, and phloem contains plant sugars, so aphids are pretty much little bags of sugar. So many different insects like to feed on aphids. You might want to try to use a combination of water spray, squishing, and tolerance, just to see how the infestation evolves. Do ladybugs and parasitic wasps flock to the aphids? Will the aphids disappear in a few days, if predators are really efficient?

5) For insecticides, you may want to look for commercial insecticidal soaps. These will harm soft-bodied insects, such as aphids. Insecticidal soaps are usually ineffective against adult beatles, although they may be harmful to soft-bodied ladybug or lacewing larvae, or to small parasitic wasps. If looking for insecticidal soaps, make sure that the active ingredient only includes the insectidal soap, and not two or more active ingredients. Sometimes, insecticidal soap products are paired with a second active ingredient, which may be more harmful to beneficial insects. 

Gail Langellotto Replied June 15, 2020, 7:16 PM EDT

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