Saturday, April 12, 2014

Pest News Alert week of April 14th

Our first pest alert of the season is now out!  Please read carefully and begin to scout now.  While we may be 1-2 weeks out from the folk in Raleigh a lot will depend on the weather over the next few days.  


From: Steve Frank, Extension Entomologist

Ambrosia Beetles

Ambrosia beetle activity has been sporadic this year due to the cool spring, but now we are catching quite a few beetles. I have also had confirmation of ambrosia beetles active in the foothills. 

Ambrosia beetle management starts with reducing plant stress. In particular we have found that trees with too much water are preferentially attacked. It is easy to overwater this time of year when transpiration and evaporation are low. The next step is preventive applications of permethrin. Apply permethrin to tree trunks and try to avoid spraying the canopy. Our research shows that spraying tree canopies results in spider mite outbreaks later in the year (see the article listed: 

Cankerworms Hatching

I found the first cankerworms of the year a couple days ago. Cankerworms were very abundant last spring and we predict the same this year. Cankerworms eggs were laid over the winter and just started hatching in Raleigh last week. You can see the tiny caterpillars if you shake branches or just watch for them dangling below trees. They feed on many hardwood tree species, but willow oaks seem to be damaged most heavily. We have written a lot on the biology and management of these critters. See a recent article in American Nurseryman
( You can find information and links to other articles on our dedicated Cankerworm Project webpage ( The important thing to remember is that they only feed for 4 to 6 weeks and only have one generation per year. By the time they get big and start defoliating trees they are about to quit and pupate in the soil until fall. The best management tactic is tree banding in the fall when adults are active. This time of year there is not much to do especially for large trees.

Eastern Tent Caterpillars

Eastern tent caterpillars hatched in the past couple weeks and have already established big nests. The easiest way to deal with tent caterpillars is to prune out the nests. Eastern tent caterpillars make nests in the crotch of trees. (Fall webworms make nests at the end of branches.) So if you can’t remove the nest, you can poke it with a pole pruner. This destroys the nest so many caterpillars fall to the ground and others get eaten by birds. Opening the nest also lets parasitoids in to kill the caterpillars. For severe infestations there are some insecticide options. Products containing Bacillus thuringiensis (Bt) are effective against caterpillars. Other active ingredients labeled for caterpillar control include spinosad, Beauveria bassiana, acetamiprid, acephate, azadirachtin, and bifenthrin. Keep in mind that these caterpillars spend most of their time in a water-proof nest so contacting them is difficult. This limits the efficacy of many insecticide applications.

Extension Resources Online

We have many extension resources such as factsheets, articles, pest news, and presentations consolidated as links on my website In addition, you can visit the site to read my blog or twitter feeds. You can also sign up to follow my pest alert Twitter feed @OrnaPests and my general ecology and IPM twitter feed @ecoIPM via Twitter or by clicking the ‘Follow’ buttons on my website. @Ornapests provides short timely alerts when new pests become active in the field accompanied by pictures and links to management information. I recently posted “pdf” files of articles I have written for industry magazines and a new free book on the management of tree pests in nurseries and landscapes (

From: Matt Bertone, Extension Entomologist

A. destructor

Armored scales (Diaspididae - are one of the most common insect pests of ornamentals. More like diseases than insects, these sedentary bugs (literally – they are in the Order Hemiptera - sit and suck the sweet fluids of plants, all the while taking energy from their host and replicating as big sacs of eggs. Their babies, called "crawlers", infest new areas and settle in for the long haul of motherhood (or the short, but free, life of a winged male -

Over the past month or so we received two samples of different plants that had an interesting armored scale infestation. The first was poet's laurel ( (Danae racemosa), that looked as if it was a variegated variety from the amount of chlorosis associated with the scales.

Looking under the microscope, I noticed two types of armored scales. The first, and less common, were some typical brown, oyster-shaped fern scales ( (Pinnaspis aspidistrae). However, the most noticeable scale was one I did not recognize. It had a very thin, translucent test that resembled delicate wax paper with a bright yellow scale underneath.

When lifted off, the scales underneath looked like this.

The scale certainly had the rounded shape characteristic of most members of the subfamily Aspidiotinae (as opposed to the elongate shape of most Diaspidinae, such as the previously mentioned fern scale), but what was it? Well, I have to confess that our friend and former clinic member Dave Stephan took a peek during a visit and thought it looked like the genus Aspidiotus. Luckily, he said that because the scale book I most often reference first, Scale Insects of Northeastern North America ( by Michael Kosztarab, does not cover this genus which is primarily Southern in distribution. So I referenced another great resource Ferris's Atlas of the Scale Insects of North America. Lo and behold, Dave Stephan was right – the scale keyed out to the genus Aspidiotus and further to the species A. destructor, the coconut scale (

Luckily, I had identified that sample, because the same day there was an image of aucuba ( (Aucuba japonica) that was submitted with a potential scale infestation. Although I was not able to ID the species from the pictures, when the sample came in I recognized the similarities with A. destructor.

After clearing some specimens, I was able to definitively ID them as the same scale. Was this a coincidence? Probably, but who knows whether these scales are becoming more abundant. Our clinic records show that A. destructor was only submitted and identified four times in the 14 years prior to these two samples. Does that mean that we will be seeing more of this scale? I am not ready to conclude that, but if more are submitted this year we may have to investigate what's going on.
Aspidiotus destructor was described by Signoret in 1869 and goes by several common names including bourbon scale and transparent scale (I am assuming based on the thin test). The scale appears to be Southeast Asian/Pacific in origin, but has been spread throughout the world. Although mainly a pest of coconut and banana, it is extremely polyphagous being found on over 60 families of plants. The genus is characterized by the following traits that can be seen in the title image (Ferris, 1938).

* absence of paraphyses or intersegmental scleroses
* three pairs of lobes with no indication of a fourth pair
* plates long, flat and fringed (two between median lobes, two between median and second lobes, three between second and third lobes, and a variable number beyond third lobe)
* characteristic sclerotization on dorsum of pygidium

The scale can cause significant economic damage at high densities (which can be common), stunting plants and eventually killing them if enough of the leaves become unable to undergo photosynthesis. Treatments can include chemical control
(, but there is also a diversity of natural enemies known to attack the species including various fungi, ladybugs, thrips, mites and several parasitoid wasps, most of which are in the family Aphelinidae ( In fact, after clearing the scales from the aucuba, I noticed some sinister-looking aliens inside a few of the scales that are certainly wasp larvae and likely a species of Aphelinidae (below "A").

I don't know whether or not the wasps are able to keep these scales in check alone, but there were at least a few being eaten by these tiny larvae. Every bit helps I guess!


Ferris, G.F. 1938. Atlas of the scale insects of North America. Series 2. Stanford University Press, Palo Alto, California.

Signoret, V. 1869. [Essay on the gall forming insects (Homoptera – Coccidae) – 3rd Part.] Essai sur les cochenilles ou gallinsectes (Homoptères – Coccides), 3e partie. Annales de la Societe entomologique de France (serie 4) 9: 97-104.

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