Damage:

Irregular blotch mines are found on the upper surface of the foliage. Some are as large as 2 inch (12 - 13 mm) in diameter.  The young larva is a sap feeder (on juices from the underlying cells that contain chlorophyll) during the first instar and forms a flat, epidermal, linear, pale green mine that is hardly noticeable.  This linear mine gradually widens into a blotch mine and becomes more noticeable as the larvae change from sap feeders to tissue feeders. At this time, mines may appear as light-to-dark brown blisters on leaflets.  Fresh mines are sometimes whitish and very noticeable.  They are often referred to as “frog eye”.  Blotch mines near the leaf edge are often a little drawn or puckered and thus tent-like in appearance. 

Seasonal History:

Larvae pupate in flat, oval cocoons of densely woven silk within the upper blotch mine.  The pupa wriggles free of the cocoon and breaks through the upper leaf surface. Later, small moths with reddish-orange forewings with three silvery-white bands emerge.  There are three generations per year.  

When to Control:  Control measures are seldom needed.