Borer Damage
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Figure 1. Holes in trunk of Washingtonia filifera caused by Dinapate wrightii. Photo by T.K. Broschat
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Symptoms
The primary visible symptoms of borer damage caused by larvae of the giant palm borer, Dinapate wrighii, are the large (2-3 cm) holes in the upper portion of the trunk (Fig. 1). Inside this region, extensive galleries may be found. In severe cases, the palm trunk is weakened and the crowncrown:
see canopy
may fall off. The budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
or meristemmeristem:
the growing region of a plant, a special area of undifferentiated cells wherein new cells and organs are developed
may also be destroyed by the feeding larvae.
May be confused with
Holes caused by acorn woodpeckers (Melanerpes formicivorus) are similar, but smaller in diameter and are typically plugged with stashed acorns.
Cause
Larvae of Dinapate wrightii burrow into the upper trunk of palms, causing extensive structural damage and potentially death of the palm. The visible holes are the exit holes of the adult borers.
Occurrence
Dinapate wrightii infests only California fan palms (Washingtonia filifera) and date palms (Phoenix dactylifera) in the states of California, Nevada, and Arizona.
