How to make a butterfly tessellation

Click on picture to launch the ggb applet(be patient a little long to open)

http://dmentrard.free.fr/GEOGEBRA/Maths/export4.25/Butterflytess.html

A Geogebra applet in html5 with the 4.25 version

http://dmentrard.free.fr/GEOGEBRA/index.html