Watch white peach scale – crawlers coming soon

White peach scale (Pseudaulacaspis pentagona) is an armored scale common on many landscape plants and fruit trees. It has a wide host range including over a hundred plant genera such as Buddleia, Camellia, Clematis, Cornus, Euonymus, Hydrangea, Ilex, Ligustrum, Prunus, and many others. The most common host of samples submitted to the PDIC here at NCSU is cherry laurel (Prunus laurocerasus). Cherry laurel is an exotic species which of course is installed in nearly every new landscape I see.

White peach scale females and males on cherry laurel. Photo: SDF

Like most armored scales white peach scales are sexually dimorphic. The females are waxy bumps on twigs but the males grow wings and look like an actual insect. The males emerge from ‘pupal cases’ (not technically pupae). Twigs become covered with the fluffy white pupal cases. This is the easiest time to see and diagnose white peach scale infestations.

Female white peach scale with cover removed surrounded by fluffy white male pupal cases. Photo: SDF

Of course the males come out to mate. Two weeks after the males emerge females will begin producing eggs and crawlers will start hatching. Scouting for the males, even though they do not feed, gives you a head start to plan your management approach.

White peach scales have 3 to 4 generations per year. Infestations are often concentrated on particular branches since scales do not move very far. Dense infestations can kill the individual twigs they are on. Minor infestations in landscapes should be monitored. You can probably inspect most cherry laurels and find some of these. That doesn’t mean you need to treat them; they can just hang out in low densities for years controlled by natural enemies. Plant stress and insecticide applications, like mosquito sprays, could increase the likelihood many armored scale species become problems.

March 7th, 2017|Categories: Landscape IPM|Tags: , |

New paper: Urban warming reduces aboveground carbon storage

This is a guest post from our former student (now postdoc at Harvard) Emily Meineke.

Through years of studying urban trees and the insects that eat them, we, the Frank lab, have discovered that warming in cities leads to more pests. We also know how: where it’s warmer, insects survive and reproduce better, and the effects of their natural enemies are diminished. In most conversations we have about this work, explaining these discoveries leads to the question: but what does this mean for the trees?

Street trees perform essential services like removing pollutants from air. Photo: EK Meineke

Street trees perform essential services like removing pollutants from air. Photo: EK Meineke

I tackled this question with the help of Elsa Youngsteadt by studying how warming and pests affect tree drought stress and functions like photosynthesis and stomatal conductance. Of course, as in my previous work, I studied the charmless but interesting oak lecanium scale on willow oaks which are among the largest and most common street trees in Southeastern cities.

Oak lecanium scales on willow oak. Photo: EK Meineke

Oak lecanium scales on willow oak. Photo: EK Meineke

Over three years we took hundreds of tedious measurements (thanks Elsa!) to figure out how fast our trees were growing and thus how much carbon they were removing from the air and storing in their tissue. This is called carbon sequestration and is a critical way trees reduce carbon pollution and global warming.


Elsa measuring photosynthesis. Photo: EK Meineke

In a new paper, we show that the urban heat island effect significantly reduces street tree growth. This is because trees in warmer urban areas photosynthesize less. When these effects were scaled up to all the willow oak street trees in Raleigh, warming reduced citywide carbon sequestration by 12%. However, insect pests like scales and spider mites had minor effects on tree growth compared to warming, at least in the short term.

Oak spider mites damage leaf cells and reduce photosynthesis. Photo: EK Meineke

Oak spider mites damage leaf cells and reduce photosynthesis. Photo: EK Meineke and A Ernst

These results lead to several recommendations for urban forest management. First, because urban and global warming are becoming more intense, urban trees will store even less carbon in the future. However, managers may be able to reduce these effects by planting trees that are more tolerant of hot urban conditions. This highlights the need for research to identify what trees are appropriate to plant in hot urban environments. In general, this research makes us excited about science that will help landscape designers tailor green infrastructure for resilience to climate change and intensifying urbanization.

Our results also highlight the utility of cities as large-scale natural climate experiments, in which sessile organisms, such as trees and many insect herbivores, are confined to different thermal environments in close proximity. The range of urban warming they experience parallels the extent of global warming expected regionally, outside the city, over the next several decades. Therefore, cities can serve as experiments that allow scientists to address questions that are otherwise difficult or impossible to approach, such as the effects of warming on mature trees.

Meineke, E.K., Youngsteadt, E.K., Dunn, R.R., Frank, S.D. (2016) Urban warming reduces aboveground carbon storage. Proceedings of the Royal Society – B 283: 20161574 DOI: 10.1098/rspb.2016.1574

October 7th, 2016|Categories: Urban Ecology|Tags: , , , , |

Crape myrtle bark scale: New tree pest has arrived in NC

A couple years ago I began warning about a new pest that was spreading throughout crape myrtle country. Now, the crape myrtle bark scale has arrived. From the severity of the infestation it looks like it actually arrived many years ago but now it is “official.” This is bad news because crape myrtles are one of our most commonly planted trees in yards and along streets. Crape myrtles are typically almost maintenance free (unless you top them) but now they will require pest management to stay healthy and beautiful.

Crape myrtle bark scale. SD Frank

Crape myrtle bark scale. SD Frank

Female scales produce fluffy white filaments that cover their body. In spring they produce eggs beneath their body then die. Tiny crawlers hatch from the eggs, settle in their new spot, and begin producing white filaments. They have at least 2 overlapping generations. At low density, crape myrtle bark scale feeds in rough areas around branch collars but as the population increases all the bark may be covered. These scales are most often noticed because trees become covered in black sooty mold. At first many people assume this is from crape myrtle aphids so the scales may go undetected. If you notice unusually heavy honeydew and sooty mold on crape myrtles take a closer look at the bark.

Crape myrtle bark scale is a felt scale related to azalea bark scale and oak eriococcin scale. They feed on phloem like other “soft scales”, thus the honeydew. Even though there is not a lot of efficacy data available drench applications of neonicotinoids are typically effective against phloem feeders. However, since crape myrtles flower continually and attract a slew of pollinators be sure to read the labels for restrictions on using them. Insect growth regulators such as pyriproxyfen and buprofezin are effective for many other scales and may be a good option. Horticultural oil, especially the heavier dormant rate, can reduce scale abundance also.

Crape myrtle bark scale on a rough branch collar. SD Frank

Crape myrtle bark scale on a rough branch collar. SD Frank

There are many subdivisions and streets in North Carolina lined with crape myrtles. Inspect these trees to determine when they become infested. Also consider diversifying the tree planting of your neighborhood. Luckily this pest does not kill trees outright like some other exotic pests increasing tree diversity helps ensure all the trees are not infested or killed at once by a single pest.

August 8th, 2016|Categories: Landscape IPM|Tags: , |

Rare sight, common occurrence: Parasitoid wasp emerges from a scale insect

This is a guest post by PhD student Emily Meineke

Coccophagus lycimnia freshly emerged from a gloomy scale.  Photo: Emily Meineke

Coccophagus lycimnia freshly emerged from a gloomy scale. Photo: Emily Meineke

If I’ve learned anything during my graduate career, it’s how to count scale insects. On a rainy June day, I sat at a microscope with forceps trying to discern bark from insects that mimic bark. My targets were armored scale insects, which are essentially tiny bags of plant sap. The adult females have vestigial or no legs, and move around only in the beginning of their lives. The rest of the time, they lie under a cover built from their excrement and wax and eat plants. If they outbreak on a plant in your yard, you might think it looks sad and kind of grey. But you might never know who did it.

Usually these excursions under the microscope are Zen, which is to say not very exciting. But on this day, I saw something rare, an event that happens every day everywhere but is almost never seen by people. I saw a tiny head peeking through a tiny hole in one of the scale insects’ covers. And when I poked the cover, it started chewing its way around the hole.  Here’s a video I took of it in action.

This was a parasitoid wasp, specifically Coccophagus lycimnia, which is a jack-of-all-trades, yet master plant protector. I found it attacking gloomy scale, a maple pest, but Coccophagus lycimnia attacks all kinds of scale insects, including armored scales, soft scales, and mealybugs, in forests, cities, and orchards, which is to say, pretty much everywhere on a slew of plant species (see Universal Chalcidoidea Database). It is an especially effective parasitoid of soft scales, in that it attacks immatures and prevents oviposition, while many other parasitoid species reduce egg production in soft scales but do not prevent it.

Parasitoids protecting street trees are diverse. We’ve documented upwards of 10 species that attack one scale insect species. While people run into certain parasitoids often—you’ve probably seen tomato hornworms covered in braconid cocoons—those that attack street tree pests are difficult to observe because they are smaller and live up in trees. They look like gnats to the naked eye, but under a microscope their metallic armor is striking and makes me wonder what else in the world I’m missing because I haven’t looked hard enough.


Pachyneuron sp., another parasitoid that protects trees. Photo: Andrew Ernst


Blastothrix sp., another parasitoid that protects trees. Photo: Andrew Ernst

Parasitoids are natural, free pest control along with other natural enemies like lady beetles. Insecticide applications can kill them, including Coccophagus sp. (Suma et al. 2009). Horticultural oils are effective against many scale insect species and can serve as a non-toxic alternative for natural enemies.


Universal Chalcidoidea Database:

Suma P, Zappala L, Mazzeo G, Siscaro G (2009) Lethal and sub-lethal effects of insecticides on natural enemies of citrus scale pests. Biocontrol, 54, 651-661.

For more information

Rakimov A, Hoffmann AA, Malipatil MB (2015) Natural enemies of soft scale insects (Hemiptera: Coccoidea: Coccidae) in Australian vineyards. Australian Journal of Grape and Wine Research, 21, 302-310.

Tena A, Soto A, Garcia-Mari F (2008) Parasitoid complex of black scale Saissetia oleae on citrus and olives: parasitoid species composition and seasonal trend. Biocontrol, 53, 473-487.

August 12th, 2015|Categories: Natural Enemies, Urban Ecology|Tags: , |

Euonymus scale second generation

Female (gray) and male (white) euonymus scales and chlorotic yellow spots on leaves. Photo: SD Frank

Female (gray) and male (white) euonymus scales and chlorotic yellow spots on leaves. Photo: SD Frank

It seems like everything is labeled ‘next generation’ or ‘second generation’ to imply a better, more sophisticated version. The second generation of euonymus scale is about the same as the first except a bit harder to manage. This is because the first generation is usually synchronized so all the crawlers on a plant emerge within a couple weeks or even a couple days. However, by the second and third generations they fall out of sync as some develop faster than others. Thus, for the rest of the summer you will find all stages of the scale at the same time; the soft vulnerable crawlers will be mixed with tough armored adults.

A good way to manage euonymus scale is to remove euonymus from your landscape. If you have the plant you are guaranteed to have the scale. If you are a grower or just love the shiny evergreen leaves you can treat euonymus scale with insect growth regulators or some of the neonicotinoids including dinotefuran, thiamethoxam, or acetimiprid. (Remember imidacloprid is NOT effective for armored scales and in some cases makes them worse.)

Euonymus scales on a stem. Photo: SD Frank

Euonymus scales on a stem. Photo: SD Frank

Euonymus scale infests the leaves and branches of euonymus. It is noticeable by the yellow chlorotic spots on the tops of leaves where scales are feeding below. You will also see white fuzz which are the unarmored male scales. The females are gray and oyster shell shaped.

June 26th, 2015|Categories: Landscape IPM|Tags: , |

Cottony puffs on holly leaves – camellia scale

This week I found cottony camellia scale ovisacs on hollies in my yard and on campus. Cottony camellia scale, Pulvinaria floccifera, is related to other cottony scales such as cottony maple leaf scale, Pulvinaria acericola, and cottony maple scale, Pulvinaria innumerabilis. Cottony camellia scale seems most common on hollies but is also a pest of euonymus, camellias, and other broad leaf evergreens. The adults lay eggs on the undersides of leaves in late spring and early summer. The ones I found have probably been present for a week or two (sorry I can’t look at every plant everyday) though no crawlers were present. Crawlers hatch and find a feeding site on the underside of the leaf and settled down to feed on phloem throughout the summer. In spring adults continue feeding then produce ovisacs that contain several hundred eggs.

cottony camellia scale cropped

Cottony camellia scale ovisac on holly. The brown spot in front is the female scale producing the ovisac behind her. Photo: SD Frank

Cottony camellia scale produce a lot of honeydew that causes holly leaves, particularly inner leaves, to get covered in black sooty mold. Control of these scales could include systemic neonicotinoids such as imidacloprid, dinotefuran, thiamethoxam, or acetamiprid. Consider the product labels when selecting these (or any) insecticide. Neonicotinoids and most other insecticides cannot be applied when plants are blooming. Hollies are finishing blooming now but when scale ovisacs first showed up they were in full bloom. Depending on the level of infestation and the tolerance for some scales horticultural oil could be used to maintain scales at low levels. Just be sure to cover the bottom of leaves and inner leaves.

Several cottony camellia scale ovisacs on holly leaves. Photo: SD Frank

Several cottony camellia scale ovisacs on holly leaves. Photo: SD Frank


May 28th, 2015|Categories: Landscape IPM, Nursery IPM|Tags: , |

Gloomy scale crawlers are active and vulnerable

Adult gloomy scale. Photo: SD Frank

Adult gloomy scale. Photo: SD Frank

Gloomy scale, Melanaspis tenebricosa, is an armored scale that feeds on maples and other tree species. It becomes very abundant on red maples on streets and in landscapes and can cause branch dieback and tree death in some cases. It is not unusual to find trees with nearly 100% of their trunk covered in scale. Street trees are particularly prone to gloomy scale. Crawlers of this scale are active now and can be seen on bark and under scale covers. One of the reasons we have found this to be such a pest is that female gloomy scales produce about 3 times as many eggs when they live on relatively warm trees (like in a parking lot) than when they live on cooler trees (like in a shady yard). This amazing work is outlined in a recent paper by Adam Dale.

Control of this scale is complicated because crawlers emerge over 6-8 weeks so it is impossible to treat all the crawlers at once with horticultural oil or other contact insecticide. This is different than in other scales, such as euonymus scale, in which all crawlers are produced within a narrow window of 2 weeks or so. Adam Dale took a video of some gloomy scale crawlers so you can get an idea of how tiny and nondescript they are. This may also give you an idea of why scales are so vulnerable at this stage to the environment, predators, and insecticides like horticultural oil. Once they produce their thick waxy cover they are much less vulnerable to all these factors.

May 21st, 2015|Categories: Feature, Landscape IPM, Urban Ecology|Tags: , , , , |

Millions of scale insect predators hatching…careful they look like mealybugs!

Two larvae on willow oak trunk. Photo: SD Frank

Yesterday on campus willow oak trees were covered in millions of what looked like mealybugs. But they were faster than mealybugs and constantly moving around the tree bark. Mealybugs don’t move much. Matt Bertone at the NCSU PDIC identified them as larvae of lady beetles that specialize on scale insects. This has been a crazy year for lecanium scales. It seems to me like there are more of them on more kinds of trees than ever. As all the lecanium crawlers hatch out these lady beetle larvae are hatching too. These lady beetles are in a couple related genera probably including Hyperaspis spp. You can read more about them in a previous post with great drawings. The important thing is to recognize they are not pests, they are predators so you can calm people (yourself) down who fear for their trees and may what to spray them.

May 15th, 2015|Categories: Natural Enemies|Tags: , |

Tea scale causes yellow spots on camellia leaves…Crawlers hatching now

Tea scale males and females on the underside of a camellia leaf. Photo: SD Frank

Tea scale males and females on the underside of a camellia leaf. Photo: SD Frank

Tea scale, Fiorinia theae, is common on camellias.  It is an armored scale that lives on the underside of leaves.  You can find it on almost any camellia by looking for inner leaves that have yellow spots on top. When you turn it over you will see tan canoe-shaped scale covers and some white fluff from the males.  These are tough to treat because the heaviest infestations are often deep within the foliage of large bushes.  They have multiple generations per year that start to overlap. The crawlers are very small but you can seem with the help of a decent loupe. They are yellow with black eyes. When I was flipping scale covers last night about half had crawlers wriggling under the cover and half just had eggs. A few crawlers were out on the leaf trying to find a spot to feed. So it is early in the hatching at least around campus. You can find a Insect Note with more information and recommendations here.

Yellow spots caused by tea scale feeding on the lower leaf surface and some female tea scales. Photo: SD Frank

Yellow spots caused by tea scale feeding on the lower leaf surface and some female tea scales. Photo: SD Frank


May 15th, 2015|Categories: Landscape IPM, Nursery IPM|Tags: , , |

Japanese maple scales hatching

Japanese maple scales on dogwood. Photo: SD Frank

Japanese maple scales on dogwood. Photo: SD Frank

Japanese maple scale, Lopholeucaspis japonica, is an important pest of nursery and landscape plants. Japanese maple scales feed on dozens of woody plant species including maples, hollies, and boxwood. 

It has been spreading throughout the Eastern US over the past decade and now seems common in NC nurseries and landscapes. Just this week I have seen it on a dogwood and on a red maple without really looking for it. In fact I was looking at other scale on these trees then noticed in the background these other tiny white armored scales.

Japanese maple scale eggs. Photo: SD Frank

Japanese maple scales are very small and slender armored scales. If you flip the cover you will see a purple body or this time of year eggs. You can expect egg hatch and crawlers soon and crawlers may already be active in warm urban sites. The difficulty controlling these scales stems from their 3 or 4 -or more- overlapping generations. Since all life stages can be present at any time, horticultural oil or other insecticides that kill crawlers, will leave behind adults and eggs to repopulate the plants.

Stanton Gill and Paula Shrewsbury at University of Maryland have done a lot of work on this pest and produced good extension publications.

May 7th, 2015|Categories: Landscape IPM, Nursery IPM|Tags: , , |