Garden Therapy Notes

 A Collection of Gardening Information and Inspiration

 
 

  

 

How to Get Rid of Spider Mites on House Plants

 

So I think I have spider mites!!  People usually don’t know their plant has spider mites until the leaves are crisp and dead.  And even then some still might not know what the heck happened to their once lush and green plant. This is because it can be difficult to see the spider mites and the webbing they produce especially if you don’t look real close.  Spider mites can be very destructive very quickly.  But if the plant is treated early enough the spider mites can be eradicated very quickly.  I’m writing this article to further understand what a spider mite is, what the initial leaf damage looks like and which plants are most susceptible. Lastly, I want learn how to get rid of them so that the plant can grow happily.

What are spider mites?  The most common species in this Tetranychidae family is the two-spotted spider mite Tetranychus urticae.  Another common name for this pest is red spider mite.  Most likely this is the spider mite I have on my plant.   The larval stage has six legs and the mature adult mite has eight legs like a spider (1).  The mite is similar to a spider because of the webbing it produces.  However, the webbing is delicate and not used for trapping prey. They are 0.5 mm in length making it difficult to see them but if I look close and focus on the tiny speck I can see them move (1).  They feed off the plant by sucking sap from the leaves (2) . Most of the time, especially during the summer when it’s warmer, they are green-yellow with two black spots on the body (1).  These two black spots give them the name two-spotted spider mite.  When the days get shorter, especially in the winter when temperatures are cooler, the maturing adults turn red (1).  This gives them the common name red spider mite.  A home that tends to stay cool during the winter will encourage the female mites to stop feeding and hibernate.  This behaviour is called diapause (1).  When the days get longer after winter and the house warms up the mites will come out of diapause and start feeding and reproducing (1).  The adult female will lay eggs on the underside of the leaf (1).  The less humidity in the air the faster they reproduce (1).  Most homes have fairly dry air and this is an important reason to mist susceptible plants more frequently, at least 2 times per week.  If the plant perishes the mites will travel to other plants with the help of their silken strands (1).  It is best to treat the plant before I see webbing. 

Leaf Damage Caused By Spider Mites: I always do a little checspidermites on palmkup on my plants when I water them. I look closely at the leaves to make sure they are healthy and perky. Looking at my ivy plant today I noticed some damage from spider mites. Some of the leaves looked pale yellow with some yellow speckles. Some of the leaves were crispy brown and fell of the plant. This discolouration is caused by the mite feeding off of the leaves. I felt the leaves with my fingers and noticed a gritty texture on the underside. This gritty texture is a combination of mites, eggs and webbing. I misted the leaves and noticed a light hallow webbing around the leaves and stems.   

 

Note to self: Spider mites can get into the house from my shoes or clothes. They survive outside on host plants such as chickweed (1).  The houseplant may have had the mites before I brought it home from the store. Try to buy plants that were most recently delivered to the store. They are more likey healthier.

Plants Susceptible To Spider Mites: Spider mites will not infest all plants. It appears that they prefer some plants over others. I’ve dealt with this pest many times on a variety of plants including Palms, English ivy, Hibiscus, Passion Vine, Dumb Cane and Norfolk Island Pine. I will keep a close eye on these plants if they are in my home and treat them a couple times a week regardless if they have spider mites or not. 

How To Treat House Plants With Spider Mites: Homes tend to stay fairly dry and this encourages feeding and reproduction. Mist infested plants 2 times/weeks with a mixture of water and liquid soap. A spray bottled filled with water with a couple squirts of liquid soap will work. I know there are other recipes but this seems to work well. Remove dead leaves and stems and dispose right away to reduce the spread of the pest.  I find that this pest can create a lot of gritty dirt on the leaves especially on ivy. Wash the plant 1-2 times/month. If the plant is small wash it in the sink. Larger plants, like my ivy, can be brought outside and washed with a hose. I will continue misting my ivy with soapy water regardless if it has spider mites or not. This will help deter the spider mites.

Best of Luck and Never Give Up

Sincerely,

Trina Alix 

 

Reference

1)     Garland, J., Howard, R. and Seaman, W. 1994. Diseases and Pests of Vegetable Crops in Canada. Pages 324-326

2)     Hessayon, D. 1991. The New House Plant Expert. Page 244

 

 

 

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