Recently I noticed there are lots of these bugs in my garden, sometimes these bugs have white cotton like tail grown.
Anyone knows the name of these ugly suckers?
The photo is poor. I cannot zoom any larger nor can I see a good side view. You mention it "jumps". it does look like it could be a species of "leaf hopper" (this is a common name). There are MANY genera and MANY species to consider in this group of insects. They are of the insect order Hemiptera (True Bugs), so you are right in that respect - they are "bugs". They come in all sizes, colors, and shapes. Some might be considered "ugly" while others may be considered quite beautiful. Some even have fuzzy white growths near the back end. Yes, they are "suckers" of plant sap, so you may be right there as well. They suck the sap out of plants for food. Please see the link below. It may contain more information that may help you with a better identification of your "bug".