Hi Wilson, I saw your posts on gesneriphiles this morning but it was early and I wasn't awake then. I really am not sure what your problems are so I may only add to the confusion, but here goes:

The worms don't sound good. This may be a larvae, such as fungus gnat larvae or sciarid fly larvae. It may be causing problems such as you have noticed. It can be treated with non-toxic insecticides that contain the product Gnatrol. This is a bacteria (bacillis thuringensis Serotype H-14) that infects the worms and kills them. I have a product called Knock-Out Gnats with this as the active ingredient. It is sold by Gardens Alive, a mail order company, located in Lawrenceberg Indiana. Perhaps you can find their website or another product containing Gnatrol from a web search. It is sprayed on the foliage and works pretty fast. A different version of the bacillis is used in products to control cabbage worms, catapillers, and other larvae. The general term for such products is a Biological Larvacide.

The second problem sounds familiar but I am not sure what it could be. Possiblities are mites, fungal or bacterial infection. Being in Singapore, I imagine that your plants never experience temperatures below 60 degrees F. I have had problems like this in the past, but usually with cool indoor conditions as a suspected culprit. I would suggest restarting the plants under high humidity, such as an enclosure and under lights. The bright even lighting and humidity will provide optimum conditions for the plant to grow. Then, when it is very healthy, you can remove it from the enclosure. Are you growing under lights? I find that here, episcias do best under lights--even better than on windowsills.

The third problem also sounds like either coolness, too much light or some other cultural problem. I find episcias really respond to frequent repotting, taking of cuttings of crowns or stolons, and general reestablishment of plants. Lastly, I don't know how winter in your version of the tropics affects episcias. Our climates are so different it seems that you really need help from someone like Leong Tuck Lock who lives in Malaysia and grows many gesneriads including episcias. The "Malay" series of hybrids are his.

Jon, in sunny cool N. California (San Francisco Bay Area)