The roots of many clematises are knotted, like as appear the roots of the grape vine when attacked by Phylloxera. The plants so attacked dwindle away in a year or two Professor Riley decides it not to be the work of a Phylloxera, but of another insect, an Anguillula. Besides this, some species are attacked by a borer allied to that which attacks the peach tree; that is an Aegeria.

There is another, fungus disease apparently, which is a fearful scourge on Clematis Jack-mani, and which keeps it always scarce.