Thrips on Indoor Succulents
Question for Mary:
I have a query regarding succulents. I bought two tiny cathedral plants about 30 years ago on Canal Street in New York. They grew into a huge gothic cathedral, so beautiful, 11–feet tall in my livingroom. Had to cut off the tops, and now they are 11 feet tall, too. Very easy to propagate. Have given many away as beautiful gifts. About 20 years ago, when I finally weaned myself from topping noble firs for magnificent Xmas trees (they look splendid in our Edwardian flat with its tall ceilings), I started decorating the cactus, and it looked marvelous too. However, about five or ten years ago, a thrip blew in, and I have gone the rounds trying to get rid of it “organically”: Neem, purchasing an electric atomizer, even letting hundreds of lady bugs loose in the flat (never do this!), but I cannot seem to stop the infestations. I may have to compost entire plants… Any advice?
Answer from Pat:
Cathedral plant (Euphorbia trigona) grows extremely well as a houseplant, but needs occasional diluted fertilizing during the growing months, in addition to well-drained soil, and adequate light with no direct sun. I have seen several huge ones growing indoors. Due to this euphorbia’s multi “trunks” getting rid of a persistent pest such as thrips without spraying is more than a challenge, it’s nigh impossible. Luckily, Spinosad will control thrips. This is an OMNI-registered product and so it is safe to use indoors and since there are no bees indoors it can’t hurt anything. Nonetheless, one should take care to protect your lungs and not to breath in the product while spraying. (Covering a large plant with a big shopping bag or large trash bag while spraying can help accomplish this.) Also clean up and replace the the top 1/4 of the soil or rock in the pot. You may need to spray more than once. Out in the garden thrips are best controlled by beneficial insects but I can just imagine what it would be like to release lady bugs inside the house. A noble idea with tragi/comedy results.
PS About the ladybugs in the flat… They simply flock to the windows to get outside. They don’t care about the feast of thrips on the indoor plants. I even made little landing pads in the branches, but it did no good…;-) I ended up catching and transporting dozens of them–I hope most– into the backyard–such adorable little creatures, they can live over a year in the wilds! But many died or were caught in house spider webs before I could get to them. Trag-comic is the word!
Thank you for the Spinosad tip! I looked it up and it sounds like a terrific product (interesting that a scientist found the new species of bacteria in an derelict factory while vacationing in the Caribbean!). Too bad Dow is the only manufacturer–I hate supporting them because of their biochemical warfare products (napalm and Agent Orange, to name two charmers). That said, i will definitely give it a try, as I am desperate. Entrust is the formula that is Omri-certified.
Re: Spinosad: Please aware this stuff kills bees, or makes their larvae sick if pollen having been sprayed with it is transported back to the hive. Please read my articles on “Please Save Our Bees.” (Parts 1 and 2.) Thanks! https://patwelsh.com/wpmu/blog/bees/please-help-save-the-bees/
Yes, Pat, I got that. I will make sure that none escape the premises when I use it. We are into bees, and intend to set up hives in the next year or two! I will read the articles! Many thanks! Love and blessings
Great! Bees are great fun to keep. Prevail on any neighbors with lawns to feed their lawns with chicken manure, or at least without white-grub control in their lawn fertilizers.
My brother was the bee keeper on our farm and learned how from government pamphlets. Farm pamphlets were free, easy to understand and full of diagrams. We used to pore over them and even kids like us could learn all kinds of stuff that way, like how to keep rabbits and pigeons. Later, when John was in college at Berkeley on the GI Bill, he saw an ad for a beekeeper. He answered the ad and found himself working for a family of eccentric white Russian immigrants, a family of dancers who were followers of Isadora Duncan. They lived in a Greek temple half way up the Berkeley hill. My brother John not only kept their bees for them but organized and shelved their library which previously was stacked in piles all over the floor of their living quarters. The son Duravol is still alive and living in Florida. One of the happiest memories of my youth was when John invited me to San Francisco to spend a holiday weekend. I was in college too but poverty-sticken. Nonetheless, I managed to scrape up enough money to pay for a seat on the Owl, and sat up all night on that cheaper, inland, overnight train from LA.. On Saturday night John and I double-dated with Vol and his sister. We danced the tango at a Greek restaurant almost all night until the orchestra gave up exhausted. We were the only couples on the floor. Vol was a divine dancer. Bees did this for me.
You mention replacing 1/4 of the soil in the pot after treatment with Spinosad. Must the Spinosad saturate the earth in the pot–i.e., do thrips reside there? I ask this because the Neem ended up killing many of the earth worms in the pots, and I would like to prevent that happening again… Also, the shallow, compact root structure of the succulents make it difficult to remove earth without damaging them. I would like to cover the pots with canvass to avoid saturation–maybe just include the base of the trunks in the spraying? Thanks so much!
Whenever using any product follow the directions on the container exactly. Spinosad is not intended as a soil drench. If it’s difficult to replace the top of the soil, simply skip that step. You could use diatomaceous earth on top of the soil to get rid of any thrips that might be hiding there. This is unlikely to harm earthworms. And yes, be sure to spray the plants thoroughly.