How to spot it

Slim beetles about 1/4 inch long, blue-black with cream squares and a red edge. The larvae are soft and gray; dark eggs stand on end along the spears.

What it does

They chew and scar spears and strip the ferns, which weakens next year's crop.

What to do now

• Pick off adults and larvae, and brush the eggs off the spears.
• Harvest every day or two in season.
• Spray neem or spinosad on the ferns if they're many.

Keep it away next time

• Cut down old ferns in late fall and clear the debris.

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Plants it affects