Subject: What kind of ant has wings and only comes out after a big rain??

We have these ants every year that come out only after it rains alot.  This 
year they showed up in late June. They are black and all of them have wings, 
most die in a few weeks. There are usually very large piles of them.  we have a 
eucalyptus tree and that is where they always are. I can't find anything on 
them and why they only show up after it rains in June or July.  I hope you can 
help me?

Re: What kind of ant has wings and only comes out after a big rain??