The main parameters of any object in the world can be manipulated simply by clicking on that object in a particular way. Subsidiary parameters are manipulated via the object control panel. Objects in the bugworld are selected using the left mouse-button. The first time you select an object a control panel opens up showing the object's attributes. You can modify the attribute values showing in the control panel at any point, even while a simulation is running.
Some attributes have a menu which is activated by a single mouse click.
Some have a slider. And some are just text fields that you modify by clicking on them and then typing in new text. To select a new object and make its attributes appear in the control panel, you click on it with the left button. To move an object, you click down over it with the left button and move the mouse to the desired position before releasing the button. If you hold the Shift key down while doing this, mouse movements will have the effect of changing the object's shape and size rather than its location.