photographs of the cut ends of stems that do and do not show evidence that bees are present

Figure 5. The stem on the left is not occupied; the pith is undisturbed. The stem on the right is occupied by bees, who have hollowed out the pith and even left a dusting of yellow pollen at the nest entrance.

photographs of the cut ends of stems that do and do not show evidence that bees are present

Elsa Youngsteadt CC BY-NC-SA 4.0