Not really an attack but they are coming in larger numbers and they have been know to defoliate a tree or two.
They have been spotted in growing numbers between Dallas and Corpus Cristi. They appear late April to early May and can often be found on homes. Be careful — they will badly stain what ever they are on if you squish them.
They prefer post oaks but have been known to attack other oaks and also hickory trees.
The Texas A&M page has contact information if you want more information. They are asking for pictures and information if you see them. That contact information is in the second link below.
Post oak grasshoppers emerging