I returned from a few weeks away and noticed my monstera’s leaves were drooping and it seemed like more brown spots than usual (It did get a bit too much sun this summer so there were a couple brown spots previously). Upon closer inspection I noticed that some leaves were covered in brown flecks, especially on the back stems of the leaves. 2 of the leaves were also covered in a white dusting of spots on the front and looked especially droopy. I cut these two off and moved the plant to the shower where I sprayed with Safer’s insecticide. I spent some time googling and I’m wondering if these are thrips? I didn’t notice any moving insects so I’m confused. I purchased this plant almost 7 years ago when it was quite small. It’s grown to a pot thats ~15 inches in diameter and the plant itself is ~45 inches tall. It was repotted last spring and grew new leaves frequently throughout the summer. Do you think this is a case of thrips? What do you recommend as next steps? Thanks for your help!
Hi there, thank you for contacting the Toronto Master Gardeners.
Judging from your photo, I can’t be sure your Monstera is infected with thrips. While thrips are very tiny, you should be able to see them move away when you disturb a leaf. Even the slightly smaller larva, which are translucent yellow in color, can be seen crawling on the surface of the leaf. Thrips puncture the leaf and suck up the contents leaving translucent patches where they have been feeding.
Regardless of the identification of this pest, you have taken some good initial steps. I’m including below, our response to an earlier question on controlling thrips. As noted, if you have other plants, be sure to isolate your Monstera and repeat the recommended treatment as needed.
The other question is – where did this infestation originate from? Check your other houseplants to see if this issue isn’t more widespread.
The response to the earlier question also contains a link to an article on general house plant care, including a list of how to avoid introducing pests to your houseplants. (Please note, this is a US article and the chemical-based treatments/controls are not applicable in Ontario, but the other information is sound).
Good luck in dealing with this issue. As you and your Monstera have been together for 7 years you are obviously providing the conditions and care it requires.