Tiny black bugs on marigolds - Ask Extension
Hi! I've been searching but can't seem to find an identification for the gathering of insects on my marigolds. They're very small (see photos), thin, ...
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Tiny black bugs on marigolds #755653
Asked June 11, 2021, 7:26 PM EDT
Hi! I've been searching but can't seem to find an identification for the gathering of insects on my marigolds. They're very small (see photos), thin, they crawl and will also hop. They're dark-brown/black, have 6 legs, 3 body sections (?), and 2 antennae. I assume they may be the larvae (?) stage of some other insect, but what? There are SO many of them, they seem to favor the yellow flowers more than others. Any ideas what these are? They are in my urban garden in N Portland, and I've seen them all spring.
Multnomah County Oregon
Expert Response
Thank you for the excellent images of those tiny insects. They are thrips, Frankliniella species. They can deface flower petals by rasping the surface layer. The result typically appears as white spots and streaks, easiest to see on dark-colored petals. Thrips -- this word is both singular and plural -- also feed on pollen.
Most pesticides suggested for use when managing thrips are contact insecticides. In other words, they must contact the pest. To be effective, such products must be sprayed when the thrips are visible and the spray must thoroughly cover the plant.
Effective products include commercial insecticidal soap, applied according to label directions. Slightly more toxic, but also effective, include both horticultural oil and pyrethrin. Caution: Don't apply any pesticide if the temperature is, or will be, 80F or higher.
Aw, bummer! I knew they couldn't be good. I've avoided spraying anything so far for the bees' sake, I'll try a neem oil/mild soap solution early morning/evening to try and curb the population some. Glad you were able to identify these buggers! At least it gives me a good starting point.
Thanks!
Audrey
Audrey,
To be effective, the spray must be applied on a dry day. The current drizzling rain will only dilute the application, thereby making it ineffective.
Further, never combine 2 or more products, in this case an oil and soap, unless the labels suggest that as one way of using the products. If no label directions are available for such a combination spray, it's very likely the plants and flowers will be damaged.
To be effective, the spray must be applied on a dry day. The current drizzling rain will only dilute the application, thereby making it ineffective.
Further, never combine 2 or more products, in this case an oil and soap, unless the labels suggest that as one way of using the products. If no label directions are available for such a combination spray, it's very likely the plants and flowers will be damaged.
I neglected to mention that commercially prepared insecticidal soap is safe for bees as long as they aren't present when the spray is applied.
