Saturday, June 23, 2012

Pest News for Week of June 25th

From: Steve Frank, Extension Entomologist

Twospotted Spider Mites Abound!

Things are heating up and the twospotted spider mite, Tetranychus urticae, thrives in hot dry weather. I have found many spider mites in the landscape on roses and many other plants. It is important to scout for twospotted spider mites now because they reproduce most rapidly in hot dry weather. Under these conditions they can mature from egg to reproducing adult in 5 days! Nursery crops are especially susceptible because they may be exposed to more sun than landscape plants and receive more pesticides. Twospotted spider mites feed on over 100 plant species sucking the fluid out of leaf cells. This ‘stippling’ damage can rapidly cause entire plants to take on a bronzed appearance. Look on the underside of leaves on susceptible hosts or beat foliage on a white piece of paper to scout for spider mites. If you notice mites or damage a range of control options are available the best of which are several new miticides that provide long residuals and efficacy against all mite life stages. Broad spectrum insecticide will make mite populations worse by killing natural enemies. For more information and product suggestions visit the newly revised insect note at

Where Have All the Japanese Beetles Gone?

It is late June and so far I have not seen any Japanese beetles. I have a couple reports from around North Carolina and even reports that they are emerging in Maryland. So I guess they are trickling out but populations seem to have gotten lower and lower in the past several years. For three years in a row we have had severe droughts during the time Japanese beetles are ovipositing. They need moist soil so their eggs do not dehydrate and so tiny young larvae can borrow into the soil. Droughts have restricted successful reproduction to only well irrigated areas.

So keep an eye out and remember a few key things. Japanese beetle traps do not offer any protection to landscape plants and may actually attract more beetles on to your property so hang them in your neighbor’s yard. Likewise, treating a lawn for Japanese beetles grubs will not reduce defoliation of plants on that property since beetles fly in from great distances. Long-term protection for landscape and nursery plants can be achieved a neonicotinoid insecticide such as imidacloprid (e.g., Merit, Marathon II) or acetamiprid (Tri-Star). A new product with extremely low vertebrate toxicity but good efficacy for a number of pests including Japanese beetles is Acelepryn (chlorantraniliprole). For more information on the biology and management of adult Japanese beetles in nurseries and landscapes consult the insect note at

Please note-  Japanese beetles have been flying around for 2-3 weeks here in WNC, so applications of insecticides to control the grubs should be applied in early July on most high quality turf.  

Ugly Nest Caterpillars

Ugly nest caterpillars, Archips cerasivorana, are small green caterpillars that build webbed nests in cherry trees and a range of other plants. They are not particularly damaging to trees but attract a lot of negative attention with their ugly nests. The best option for these guys is to just prune out the nest. Even if you spray them you will still have to prune out the nest so it doesn’t look ugly so it is best to save a step.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.