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Entomology (Study of Bugs)/Spider Mites on Butterfly Bushes

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Question
Thanks for answering my question.  I have two Black Knight Butterfly Bushes that are infested with spider mites.  This is the second year this has happened, and now they are spreading to my Froebelli Spireas.  I asked a horticulturist, but he told me to ask an Entomologist.  I tried spraying them with a broad use insecticide, but since the spider mites are on the underside of the leaves and the bushes are so large it is very difficult to get them all with the foliar spray.  I thought about using a systemic insecticide to get rid of the spider mites, but I was concerned that the systemic would also kill the butterflies and bees that come to sip the flowers’ nectar.   Do you know if a systemic insecticide would kill the insects drinking the flower nectar or would it not affect them?  Please let me know.  I would appreciate it.

Thank you,
Tim Elliott

Answer
Hi Tim!

I would not use a systemic insecticide on the plants for the reasons you expressed.  You don't want to run the risk of any of the toxins being in the nectar.  In addition, they might have an adverse impact on natural predators of the mites.

There are some other options for spider mites:

1) dusting sulphur or wettable sulphur (nurseries) - avoid using during hot weather
2) predaceous mites (Phytoseiulus persimilis)(online catalogs and nurseries)
3) lacewing nymphs (online catalogs and nurseries)
4) ladybug larvae (online catalogs and nurseries)
5) Neem oil sprays (nurseries)
6) insecticidal soaps (nurseries)
7) strong sprays of water on the undersides of the plants
8) remove badly infested branches/vegetation
9) spray of 3tsp of dish soap per gallon of water.  Apply to plants..."hairy" plants may be sensitive to the soap and the leaves will burn in hot weather.

There are plenty of other organic concoctions out there, but these are the ones that I've recommended in my time as an entomologist.

Best of luck!

Entomology (Study of Bugs)

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Nathan Riggs

Expertise

I currently live in San Antonio, TX and have expertise in identifying insects, many types of spiders, and other arthropod critters that infest lawns, ornamentals, structures, trees, pets and livestock. Mites are not a strong point of mine. I'm not a licensed doctor, so I cannot provide medical diagnosis of conditions possibly related to insects or other arthropods. If you've got an interesting photo for me to see, attach it to your question, or let me know and I'll give you my email so the picture will get to me. If you have hosted an insect photo on a website, please include the link so I can go look at it and provide a faster ID for you. You may also join my group page on Facebook and post your picture at www.facebook.com/groups/antmans.hill/.

Experience

22+ years' experience as an entomologist: 5 years as a biologist with Merck Animal Health (I was part of the R&D team that worked to develop FrontLine flea and tick products) and 7 years as an Integrated Pest Management (IPM) Specialist in San Antonio, Texas with Texas Cooperative Extension.

Publications
Veterinary Parasitology, Southwestern Entomologist, San Antonio Express News, San Antonio Gardener Newsletter, Master Gardener SCION Newsletter, GardenStyleSA e-Newsletter

Education/Credentials
BS - Entomology from Texas A&M University in 1992.

Board Certified Entomologist, 1996-2000 - Medical and Veterinary Entomology Specialty (Entomological Society of America)

Awards and Honors
2000 Texas A&M University Vice Chancellor's Award in Excellence for leadership on the Texas Fire Ant Program Educational Team.

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