When a houseplant gets attacked by an insect pest, the problem can quickly spread to other plants. So first thing first, inspect your plants, especially check both sides of the leaves, for signs of pests or disease. If you find the suspect, isolate the plant. Common pest problems (eg: aphid, mosquito, scale) can mostly be solved by insect killer spray (I use Plantmate which can be bought in many flower shops). Try to identify the pests for there are different insect killers for different pests. If you can’t identity it, take a photo and show it to the people who work in the flower shop

Also, here is a good site that help identify and solve pest problems, which you may find helpful as well – http://www.gardeners.com/Pest-and-Disease-Finder/5285,default,pg.html.

Cheers!