Spider Mites = BATH TIME!



I've been looking at my Africana ansellia's for a few weeks (months) thinking they were not looking very happy...
Today I took a closer look and some of the leaves are looking very bad!
Brownish patches on the under sides of the leaves and a silvering, greyish tinge on the tops...
I looked for any fine web - none.
So I did the tissue test.
Take a damp tissue and wipe the underside of the leaves, if you get a red, brownish or orange residue.. you most very probably have the dreaded Spider mite.
I do!

Red Spider Mites if you look closely

 

Underside showing brown/red patches

 

Top of the leaf

 

 

 

Spider Mite info thanks to Wikipedia;

 

Spider mites are members of the Acari (mite) family Tetranychidae, which includes about 1,200 species. They generally live on the undersides of leaves of plants, where they may spin protective silk webs, and they cause damage by puncturing the plant cells to feed.

 

Spider mites are less than 1 millimetre (0.04 in) in size and vary in colour. They lay small, spherical, initially transparent eggs and many species spin silk webbing to help protect the colony from predators; they get the "spider" part of their common name from this webbing.

 

Hot, dry conditions are often associated with population build-up of spider mites. Under optimal conditions (approximately 80 °F or 27 °C), the red also know as the two-spotted spider mite can hatch in as little as 3 days, and become sexually mature in as little as 5 days. One female can lay up to 20 eggs per day and can live for 2 to 4 weeks, laying hundreds of eggs. A single mature female can spawn a population of a million mites in a month or less. This accelerated reproductive rate allows spider mite populations to adapt quickly to resist pesticides, so chemical control methods can become somewhat ineffectual when the same pesticide is used over a prolonged period.

Spider mites, like hymenopterans and some homopterous insects, are arrhenotochous: females are diploid and males are haploid. When mated, females avoid the fecundation of some eggs to produce males. Fertilized eggs produce diploid females. Unmated, unfertilized females still lay eggs, that originate exclusively haploid males.



After my initial  panic I took action.
I went to the shed.
No spray.
Another panic..
So after a coffee during which I contemplated dashing to the nearest shops, but then decided that I would go down the 'cheaper' home made remedy route.

I filled the kitchen sink with tepid water and added a few drops of washing up liquid. I then dunked the affected plants and using a sponge gently wiped the lengths of the leaves and the pseudobulbs. Also making sure to pour the weak soapy solution through the pots, to get any little critters that may be hiding inside the pots among the bark.

Each plant that has been in the windowsill with the affected plants (only my Ansellia's so far I think) received this treatment in fresh solution.

The treatment was repeated again, and then rinsed thoroughly in fresh tepid water to get rid of the soap.



Soapy bath.

 

 

 





Rinse time.

 

 

Possible reason for the outbreak is that the plants are in a south facing windowsill which sits over a radiator. The atmosphere is very dry as I keep the plants a lot dryer over winter.

I have put hydoleca balls in the saucers under the plants, which I am keeping damp to hopefully raise the humidity to discourage the mites.

 



There are various treatments available for Spider Mites including a non chemical option by predatory mite that feeds on the eggs and active stages of Spider Mite.

 

Oil based sprays are an option as well as systemic. Again a home made spray using  a few drops of vegetable oil (not olive which is too heavy) in a soap solution, shaken vigorously to emulsify can be used. I have avoided this as plants sprayed with oil are susceptible  to sun burn.

My plants sit in a sunny windowsill so I prefer to avoid this method at this time.

 

I will need to retreat using the soap method every 4 - 7 days for a further 2 weeks. If after this I still have a problem I will be using a systemic chemical spray.