Stephen J. Toth, Jr., editor
Volume 19, Number 7, May 28, 2004

Ornamentals and Turf

From: Stephen B. Bambara and Christine A. Casey, Extension Entomologists

We will probably mention this insect every year in the North Carolina Pest News until we stop receiving them in the Plant Disease and Insect Clinic. Euthyrhynchus floridanus is a stink bug that feeds on other insects. It is one of the more visually attractive stink bugs with three orange spots on a dark, metallic blue background. These insects overwinter as adults probably in some dry, sheltered location. Eggs are laid the following spring. Immature Euthyrhynchus floridanus are highly aggregated and even attack larger prey in concert. Apparently, aggregation behavior allows them to successfully attack prey too large to be subdued by a single nymph. Sometimes the adults aggregate with nymphs. When the bugs jab their prey with their proboscis, they inject a toxin that slowly immobilizes the prey. Plant feeding is not reported for Euthyrhynchus floridanus. This stink bug may not have a huge impact as a beneficial, but it should recognized that it is NOT a pest species.

This week, two county Extension agents mentioned the presence of scales on tulip poplar (Liriodendron tulipifera). The scales may be magnolia scales or tuliptree scales. The tuliptree scale insect is attacked by numerous parasitic and predaceous insects (including a predaceous caterpillar!). The tuliptree scale is one of our largest scale insects and is sometimes damaging to tulip trees and magnolias. It has one generation per year. Its biology is slightly different because the scales reproduce in late summer and the tiny new scales overwinter on the twigs and stems (most of the soft scale insect pests of ornamentals reproduce in May or early June). Male tuliptree scales appear in early summer and mate with the females. The females swell considerably with eggs during the summer but the eggs hatch as they are laid so that it appears the crawlers are born rather than hatched. Infested trees may become sticky with honeydew excreted by the scales and black with sooty mold fungi which grow in the honeydew. The overall tree may be weakened with sparse foliage and dead branches or the trunks may be distorted because the scales have killed the leader branches over the years. Most homeowners object to the honeydew and the wasps, flies and bees that are attracted to the honeydew. We most often recommend that the tree be sprayed with horticultural oil now and again in September on a warm day directed toward the crawler stage. This soft scale responds to the insecticide imidicloprid.

Recently we requested input from county Extension agents about plants they regretted seeing in the landscape due to the high amount of insect problems. Good integrated pest management (IPM) practices would suggest that one avoid plant material that has a high degree of insect problems. Below is the list of plants identified by the agents:

• Gardenia - whiteflies

• Peaches - scales, plum curculio, borers

• Roses - Japanese beetles

• Harry Lauder's walking stick (Corylus avellana "Contorta") - lacebugs and Japanese beetles

• Autumn Clematis - when planted too close to the house, highly attractive to flies, aphids, wasps, lady beetles and blister beetles

• Autumnalis cherry- Japanese beetles

• Euonymus japonica "Aureus" - euonymus scales

• Leyland cypress - bagworms

• Kwanzan cherry- Japanese beetles (and ambrosia beetles)

Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Last modified on May 28, 2004 by Stephen J. Toth, Jr.