Choose new start and end values of lambda between 1.0 and 4.0, and click "Redraw".
In particular, try 3.8 < lambda < 3.9, an "island of period three" in the "sea of chaos". All periods are present: can you find periods 5, 6 and 7?
Beware loss of precision if your values of lambda are very close together: don't necessarily trust the precise locations of bifurcation points!