Whiteflies on Lavender and Mint?

Asked August 28, 2020, 11:00 PM EDT

Hello! I bought a lavender plant and a strawberry mint plant from a nursery in Georgia a few months ago, and I've noticed white bugs on the leaves. I did some researching, and it seemed like they were whiteflies. On the leaves, I've found dew and cocoons/fibers that look like cotton candy. The leaves and stems at the bottom of the lavender plant are browning in random spots. However, I don't know if the browning is normal or if it can be attributed to the bugs. Compared to the severity of whitefly infestations I've seen online, I haven't observed much damage to the plants, nor have I seen the swarms of flies coming off the leaves. I've only ever found larval forms, no adult flying insects. Overall, the plants seem fine in spite of the bugs. Both the mint and the lavender have been flowering.

I've tried washing off the leaves with water, and I've killed any bugs I've encountered. It's hard to tell if it's making any difference as a few weeks later I'll just find tiny baby bugs again.

Are these whiteflies? Will they hurt my plants? If so, how can I get rid of them? I'm about to move in with a roommate who has plants of her own, so I'm worried about spreading the bugs to her plants, especially if the bugs are harmful. Thank you for your help!

Hennepin County Minnesota

1 Response

Thanks for the question.

I cannot make an identification of this insect because the pictures lack sufficient resolution and clarity. If adult whiteflies are present, you may not be able to see them easily. They are quite small and often are on the undersides of leaves. However, as they feed on plant juices they produce a very sticky substance known as honey dew. It sounds as if you have detected something like this on your herbs. As an initial step in their control, take your plants outside and with a reasonably strong stream of water, wash off all the larvae. You may have to do this a few times as additional eggs hatch. Eventually and with persistence the larvae will be gone. Then you could gently wash the leaves with an insecticidal soap or oil. Unless the infestation is extremely heavy and prolonged, little damage should accrue to your plants. The following will provide information on these and other points:

https://homeguides.sfgate.com/homemade-whitefly-insecticide-37740.html - :~:text=You can mix up a,and shake well to mix.

https://www.almanac.com/pest/whiteflies

https://www.corkyspest.com/diy-whitefly.html

https://insectcop.net/best-whitefly-insecticides/

https://www.growveg.com/guides/5-organic-controls-for-greenhouse-whitefly/

Good Luck!!