Q/A #20 -  Spider Mite Web?

January 18, 2023

Q/A #20 - Spider Mite Web?

I have a Pinguicula Pirouette. Great light from 0600 to 2300 LED, and keep in water tray. All water is distilled through a dehumidifier. Light mist 1 time a day but recently noticed webbing around plant only visible with the misting. Is this a normal spider web or should I be concerned? Or is it a mite or other pest? It doesn’t seem to be spreading but don’t feel like I can diagnose what the threat is and proper treatment should be. Thank you!
(Submitted in January 2022.)

Spider mites are pretty rare on Pinguicula. It's not a plant they go after. The webbing in your photos is also not typical of spider mites. Their webs are very fine and tightly netted than what you have. We've seen this type of webbing before and identified it as a non-pest spider, one that is likely feasting on fungus gnats, a common soil pest. There's no concern about the spider itself, but it does point to a different problem.

If you have a problem with fungus gnats (or springtails), the soil of your butterwort is too wet.  It shouldn't be sitting in water. Your sundews are fine sitting in water, but Mexican butterworts will get root rot if kept like this for long periods. They are not bog plants. (This is different from many of the temperate Pinguicula such as P. vulgaris or P. grandiflora) 

It's best to top-water them until you get runoff, then stop. They can have a small amount of water left in the tray, but be sure they use that up before watering more. These plants actually do better a bit drier. Keep the soil just moist, but never sitting in water. 

Also, in the photos it looks like these have been misted. If that's true, stop. Most of these are used to drier air. In fact we are having some issues right now in our greenhouse because it's too humid for these. Misting is also not beneficial for the other plants either. Nepenthes can actually stop pitchering when being misted regularly because the plants register it as disturbance from the humidity see-sawing up and down. Because of your multiple plants and water trays in this area, your ambient humidity will be just fine. 

I also noticed your Heliamphora sitting in quite a bit of water. This one as well will do better long-term if the water level is kept very low. They are fine with a little water in their tray, but they are different than their cousins Sarracenia in this respect, and can be more prone to root-rot if kept in a deep water tray for long periods. In our greenhouse we let Heliamphora trays go dry before adding more water. 

Submitted in January 2022. The original question and response have been edited for publication.
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