public static void main(String[] args) {
        if (args.length != 1) {
            System.err.println ("usage: Swarm <nbugs>");
            System.exit(1);
        }
        final int nbugs = Integer.parseInt(args[0]);
        SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    createAndShowGUI(nbugs);
                }
            });
    }