Miscanthus mealybugs (Miscanthiococcus
miscanthi) can damage miscanthus grass, by distorting and
stunting its growth. These mealybugs
overwinter as females loaded with hundreds of eggs in the crown
of the plant. Eggs hatch in spring into small crawlers that
move within the
growing grass sheath. Some mealybugs leave the infested plants,
being blown to new plants. Many mealybug crawlers stay on the
plant. Crawlerstake
3-4 weeks to grow to adults. Reports of the life cycle in Maryland
indicate that there are three generations per year. This is
likely to be the
case in this part of the country as well. The photos were taken
on August 19, 2003 at a planting in Indianapolis. The figures
indicate how you
can diagnose this insect before significant distortion has
occurred. Some control may be achieved by applying imidacloprid
(Merit, or Bayer
Advanced), to the soil in the spring on young plants as they
begin to break winter dormancy.
--Cliff Sadof, Department of Entomology, Purdue University |

Purple spots on the exterior are a good symptom
of Miscanthus mealybug.

Peeling back a purple-spotted miscanthus stem reveals
the waxy secretions of the Miscanthus mealybug.

A normal green stem of Miscanthus lacks purple spots.

When the green stem is pulled back there
is no waxy mealybug secretion present.

Adult female mealybug produces waxy secretion.
Smaller dusty nymph crawls on stem.
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