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The P&PDL Picture of the Week
for 25 August 2003



Miscanthus mealybug (Miscanthiococcus miscanthi) a pest of Miscanthus grass

Cliff Sadof, Department of Entomology, Purdue University

Miscanthus mealybugs 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.

Click on the small image to view a larger image.

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.

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

Photo courtesy of Steve Mayer, Marion county extension educator

A normal green stem of Miscanthus lacks purple spots.
When the green stem is pulled back there is no waxy mealybug secretion present.

 


Cicada Killer Wasps

Tim Gibb, Department of Entomology, Purdue University

Huge black and yellow wasps in parks, golf courses and back yards are receiving a lot of publicity right now. These are actually Cicada Killer wasps, and although they are intimidating, they very seldom sting. Cicada killer wasps should be considered beneficial because they kill potentially plant-damaging cicadas, but they are also nuisance pests themselves if they occur around people. The size of the wasp is intimidating enough but add to that the males annoying habit of 'dive-bombing ' anything that comes into their territory - including humans. The result is that they get peoples attention quickly.

In most cases the wasps should just be left alone as they likely will not sting and because of their beneficial cicada predatory behavior. In those cases where they cannot be ignored, using Carbaryl (Sevin) as a dust applied to the burrow entrance has been shown to offer excellent control.

Cicada Killer Wasp


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Last updated: 26 August 2003/amd
The Plant & Pest Diagnostic Laboratory at Purdue University