Scale Insect: All You Need to Know in a Quick, Friendly Guide

Scale insects are a diverse group of pests that can cause significant damage to your plants if not properly managed. They can be found on a variety of plants, from trees to houseplants, and are notorious for their ability to blend in with their environment, making them challenging to detect and control.

You may notice that your plant’s leaves or stems are discolored, or that there’s a sticky substance, known as honeydew, on them. This is usually a sign that scale insects are present and feeding on your plant. Identifying the type of scale insect is important for effective treatment, as different species require specific approaches for control. For example, the Florida wax scale is white and highly convex, whereas other scale insects may vary in color and shape.

Understanding the life cycle and habits of these pests will help you in effectively controlling their population and protecting your plants. It’s helpful to know when they’re most vulnerable, such as during the crawler stage, to determine the best course of action. Being proactive about inspecting your plants and employing an integrated pest management strategy can help prevent severe infestations and save you time and effort in the long run.

Recognizing Scale Insects

Physical Characteristics

Scale insects are small, round or oval, and have a shell-like cover. They can be white, brown, or other colors depending on the species. Identifying scale insects requires a close examination of their physical features. Here are some key characteristics to look for:

• Shape: round or oval
• Cover: shell-like and can be white, brown, or other colors
• Size: varies by species, but generally small

Types of Scale Insects

There are two main types of scale insects: soft scale and armored scale. They differ in their physical appearance and the damage they cause to plants. Let’s compare them in a table:

A few common examples of soft scale insects are the brown soft scale and white scales, which can be found on indoor plants. On the other hand, armored scale examples include the San Jose scale, euonymus scale, and oystershell scale.

By understanding the physical characteristics and types of scale insects, you can more easily identify them and take appropriate measures to protect your plants.

Life Cycle of Scale Insects

Egg Stage

Scale insects begin their life cycle as tiny eggs. Female scale insects lay their eggs in a protective covering called an ovisac. Depending on the species, a female may lay around 50 to 250 eggs within the ovisac. Here are some characteristics of the egg stage:

• Eggs are usually laid underneath the female’s body.
• The eggs can be different colors, such as yellow, orange, or black.
• The duration of the egg stage varies, but it can last from 1 to 3 weeks.

Nymph Stage

After hatching from the eggs, the scale insects enter the nymph stage, which is also called the crawler stage. In this stage, they move around actively to find a suitable feeding site. Here’s what you should know about nymphs:

• Nymphs are tiny, flat, and oval-shaped.
• They can be different colors, like their eggs.
• Nymphs are mobile and disperse to find a new host plant.
• They insert their mouthparts into the plant and start feeding on the plant’s sap.
• The nymph stage can vary in duration, but it typically lasts for up 1 to 3 months.

Adult Stage

In the adult stage, scale insects develop a hard, protective cover over their soft body. They become stationary and continue feeding on the plant’s sap. Here are some facts about adult scale insects:

• Female scale insects are often larger than males.
• Males may develop wings and become mobile in search of a female for mating.
• Adult females are mostly immobile and remain attached to the host plant.
• The adult stage can last from 1 to 2 months.

Overall, the life cycle of scale insects can vary depending on the species, but it generally goes through the egg, nymph, and adult stages. Throughout these three stages, they undergo significant physical changes and adapt to their environment while feeding on host plants.

Damage Caused by Scale Insects

Effects on Leaves and Stems

Scale insects are sucking pests that feed on plant sap, extracting nutrients from leaves and stems. When infestations become severe, you may notice leaf yellowing and premature leaf drop. In some cases, infested leaves may appear with a sticky residue, resulting from the insects’ excretions. This residue can attract additional pests, like ants or sooty mold.

Examples of plants commonly affected by scale insects include:

• Shrubs
• Trees
• Ornamental plants

Effects on Bark and Fruit

Scale insects don’t only damage leaves and stems; they can also cause problems for tree bark and fruit. As they feed on the sap, they can weaken the bark, leading to susceptibility to diseases and environmental stress. On fruit trees, scale insects can cause blemishes and even fruit drop, directly affecting crop yields.

Here’s a comparison table of some effects on leaves, stems, bark, and fruit:

To minimize the risk of scale insect damage, monitor your plants for signs of infestation and take the necessary control measures, such as removing infested plant parts and applying insecticides when appropriate. By addressing scale insect infestations early, you can help protect your plants and keep them healthy.

Habitat and Host Plants

Indoor and Houseplants

Scale insects can infest a variety of indoor plants, including houseplants and orchids. These pests feed on plant sap, which can weaken your plants and lead to various health issues. Here are some examples of common indoor plants that scale insects may infest:

• Orchids
• Peace lilies
• Ficus trees
• Various types of ferns

Scale insects on indoor plants can be managed by careful monitoring and the use of natural predators, such as ladybugs, or by using insecticidal soap or horticultural oil.

Outdoor and Woody Plants

Outdoor plants, particularly woody plants, can also be susceptible to scale insect infestations. These pests often target well-known outdoor plants like euonymus, magnolia, citrus, oak, and elm trees.

Outdoor and woody plants are considered host plants by scale insects, meaning they provide the necessary nutrients and habitat for scale insects to thrive. Host plants for scale insects include:

• Euonymus shrubs
• Magnolia trees
• Citrus fruit trees
• Oak trees
• Elm trees

To prevent scale insects from damaging your outdoor and woody plants, consider implementing an integrated pest management approach. This includes using natural predators, horticultural oils, and insecticidal soaps, as well as cultural practices such as pruning, watering, and fertilizing to encourage plant health and resistance to pests.

Prevention and Control

To prevent scale insects from infesting your plants, consider implementing cultural practices. For example, you can maintain a clean and tidy garden by removing brush and pruning overgrown plants. This helps eliminate favorable conditions for scales to breed and reduces hiding spots for pests.

When it comes to controlling scale infestations, there are several methods at your disposal. One popular method is using horticultural oil or neem oil. These oils help to suffocate and kill scale insects while also providing a protective layer for your plants. For a more biological approach, you can introduce predators such as parasitic wasps and beneficial insects that target scales as their primary food source.

If an infestation progresses, you might need to resort to stronger measures like pesticides or insecticides. It is important to carefully read the label and follow application guidelines, as certain treatments may not be suitable for all types of scales or plants.

In summary:

• Maintain a clean garden by removing brush and pruning plants
• Use horticultural oil or neem oil for prevention and control
• Introduce predators like parasitic wasps and beneficial insects
• Apply pesticides or insecticides as a last resort and follow guidelines

By implementing these strategies, you can effectively prevent and control scale insect infestations in your garden while also promoting a healthier environment for your plants.

Scale Insects Products and Effects

Scale insects are pests that can cause damage to your plants by consuming sap or plant cell contents. They produce a sticky substance called honeydew, which can lead to the growth of sooty mold. Sooty mold is a fungus that covers the leaves and hinders photosynthesis.

Both armored (hard) scale and soft scale insects can cause damage. Armored scale insects are covered in a wax-like substance, while soft scale insects excrete sugar-rich honeydew. Moreover, soft scale insects are often associated with cottony maple scale, another notorious plant pest.

To protect your plants from the effects of scale insects, here are some things you can do:

• Monitor the health of your plants regularly.
• Remove any visibly infested plant parts.
• Use insecticidal soap, horticultural oil, or chemical insecticides if needed. Follow the application instructions carefully and select the correct product for your plant.

When comparing the effects of armored and soft scale insects on your plants, it’s helpful to understand their differences:

By being vigilant and addressing the issue early, you can mitigate the negative effects of scale insects and keep your plants healthy and thriving.

Scale Insects and the Environment

Scale insects are small, sap-sucking pests that can affect various plants by consuming their sap or plant cell contents. They are typically found in trees, shrubs, and other perennial plants. These insects can have a significant impact on the environment, as some species can cause serious damage to their hosts, while others do not cause any noticeable harm even when present in large numbers¹.

There are two main types of scale insects: armored (hard) and soft scale. Armored scale insects have a protective outer covering and are generally more resilient to pesticides, while soft scale insects secrete a sticky substance called honeydew, which encourages mold growth².

In the environment, scale insects have the ability to overwinter, surviving through harsh winter months and resuming their activities once temperatures begin to rise again³. This allows them to maintain a hold on their host plants and inflict damage over an extended period.

Scale insects can also indirectly affect the environment by impacting populations of pollinators. Since they feed on sap, their honeydew secretion can attract ants, which protect the scale insects from predators. These ants can also fend off beneficial insects, such as pollinators, from visiting the affected plants⁴.

In conclusion, scale insects play a role in the environment by impacting plant health and influencing pollinators. Their presence can sometimes be harmful, while at other times, they can coexist with their host plants without causing any noticeable damage.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Barnacle Scales

Unknown insect eggs(?)
Sat, Jan 10, 2009 at 11:24 AM
Unknown insect eggs(?)
I found these on a plant in my backyard in Southern California. The plant is low and spindly and sits about two feet from a fountain that is always running. When I first took the pictures I didn’t notice the spider in the background. Yesterday, the two spiders were “face to face”. Now I notice that the one ate the other. Are they spider eggs? Did she eat him, like a black widow? What struck me about whatever these things are are their uniformity, abundance and metallic looking details.
SoCal Soundguy
Monrovia, CA

Dear SoCal Soundguy,
These are Wax Scale Insects known as Barnacle Scales, Ceroplastes cirripediformis. You can confirm the ID on BugGuide which indicates that it is a pest on quince and citrus in Florida. It is also reported from California. Images on BugGuide include specimens found on pomegranate, camellia and sage. We located a PDF online that pictures another similar looking species, Ceroplastes ceriferus, listed as the Indian Wax Scale. Soft Scale insects are plant sucking insects that can do major damage to plants if they get too plentiful. We wish you were able to provide us with the host plant name. It looks like it might be lantana, but we are not certain.

Follow up: Wax Pests
Sun, Jan 11, 2009 at 2:53 PM
Daniel,
Thanks for your prompt, informative reply. You were interested in the
plant the finding came from. Not only did I send you a picture of the
plant but I did you one better: I included a picture of the plant tag
that the horticulture garden I bought it from (Huntington Gardens)
identified it with. The plant is Salvia Ulignosa.
I didn’t realize how many of these things were on the plant until I
pulled them off (they came off easily) or clipped high denisty clusters
like the branch shown. Then I burned them with a blow torch. I figured
that was the most definitive way to destroy them, lest they survive a
trip to a landfill and cause someone else a headache. …
Chuck
SoCal Soundguy
P.S. I have so tell you how satisfying it is to write your site. Answers are typically prompt, but always knowlegable and succinct. Thank you!

Letter 2 – Giant Scale Insect from Australia

Orange furry bug
March 16, 2010
Hello, I saw someone posted a similar insect as this, and I was wondering if you found anything more out about it? I found it under a bunch of old wet leaves tucked inside an old candle holder. (i was cleaning out the candle holder and that’s how i stumbled upon it).
Thanks! Kimberly
Brisbane, Australia

Hi Kimberly,
This appears to be a Giant Scale Insect, and we did not have much luck identifying the species that was sent last month.  Eric Eaton made the tentative identification, but we would like to match both your images and the previous image to a species.  The do not appear to be the same species.

Letter 3 – Giant Scale Insect from Australia

Subject: Bug Identification
Location: Cathedral Ranges, east of Melbourne, Victoria, Australia
March 21, 2016 2:42 am
Found this on a hike in the Cathedral Ranges east of Melbourne, Victoria, Australia. Believe it’s a giant scale insect but from what I read they are in Queensland.
Signature: Aussiejill

Dear Aussiejill,
You are correct that this is a Giant Scale Insect in the genus Monophlebulus.  We do not know the exact range of various species, but Project Noah has sightings from Western Australia, so they are not limited to Queensland. 

Letter 4 – Unknown Soft Scale found on Tangerine Leaves in California

Whitefly Pupa???
March 29, 2010
3:1 before crop. I’m completely oblivious to what this is….
Found it on a tangerine leaf this December.
Jonathan Campos
Los Angeles, CA

Hi Jonathan,
This appears to be some species of Soft Scale Insect in the family Coccidae.  We found a photo on BugGuide of Saissetia coffeae that looks similar, but different nonetheless.  There is also something of a resemblance to the Soft Brown Scale, Coccus hesperidum, also pictured on BugGuide.  We are fairly certain your photo depicts a different, though related species.  Scale Insects can do great harm to agricultural crops and ornamental plants.  We are concerned that this might be a newly imported Citrus Pest as though the threat of the Citrus Psyllid, profiled on Featured Creatures, isn’t enough.

Letter 5 – What's That Bug????? Mystery Insect from Malaysia is male Scale Insect

Mutated Flying Insect ?
Location: On a small forest hill in the middle of Kota Kinabalu city, Sabah, Malaysia.
April 6, 2012 8:34 am
Hi Mr. Bugman,
I have found a strange looking insect which baffles me and my friends.
We do not even know what insect order it is from.
It looks like a mutated insect.
Description: 7mm length, Red body, black wings, black legs, black hairy antennae, black popped out eyes, back of thorax black, front of thorax contains 2 yellow bumps, white powder on thorax, several hairy long ”structures” at the end of it’s abdomen. The insect can hover high and well too. Other findings from the net – http://www.projectnoah.org/spottings/10235360
Signature: Xing

Dear Xing,
This really is a mystery.  Prior to enlarging your images, we thought it most resembled a wasp mimic moth in the family Sesiidae, but we immediately rejected that upon viewing the larger images.  Thanks so much for providing the Project Noah link and the dialog there is fascinating.  We are not convinced that this is a Planthopper, though it does share some characteristics with Planthoppers.  We wish your side angle photo had a good view of the mouthparts, as that would help to eliminate many possibilities.  This insect seems to possess characteristics that would place it in certain orders, however, it also has characteristics that would tend to eliminate those orders.  The antennae are similar to some beetles, in particular the Glowworms, but the projections at the end of the abdomen are decidedly not beetle-like.  We are going to contact Eric Eaton to see if he can provide any suggestions.  If we were to hazard a single guess on a quiz show, we would have to go with the order Megaloptera which contains Alderflies, Dobsonflies and Fishflies.

Perhaps our readers will provide some possible identifications.

Eric Eaton provides an identification.
Daniel:
This is a male scale insect.  I know!  It is positively enormous considering the size of most male scales, but that is what it is.  Thanks for sharing the amazing images.
Someone at “scalenet” might recognize this one immediately.
Eric

Thanks much Eric.
Daniel

Sure.  Margarodidae may be the family.
Eric

Letter 6 – Scale on Chinese Elm Bonsai

Location:  Mt. Washington, Los Angeles, CA
August 13, 2011
As we mentioned earlier, we had certain commitments today, and we needed to stop posting early this morning.  We have completed two of our tasks, but the letter for Elizabeth is still not completed.  We did however deal with the Scale insects on the Chinese Elm Bonsai.  This is a small grove of three trees that were raised from seedlings.  About a week ago, we noticed the Argentine ants running up and down one trunk, and we suspected they might have a small colony in the pot, but closer inspection revealed a Scale infestation that was being tended by the Ants.  

We were concerned that the roots might also be affected and we planned to repot the bonsai.  We started by pruning the branches, and then applied a mixture of chlorine bleach in water, about 1:20, with a tooth brush to remove the scale.  Then we trimmed the roots and replaced the trees into the pot, but with all new soil.  Hopefully, were were not too late to save this sentimental potted grove.  We still need to identify the Scale.

We also need to take a photo of the completed re-potted plants.

Letter 7 – Giant Scale Insect from Australia

Subject:  Orange and black bug
Date: 03/31/2021
Time: 03:29 AM EDT
Geographic location of the bug:  Queensland Australia
Your letter to the bugman:  Hello do you know what’s this is?
How you want your letter signed:  Holly

Dear Holly,
This is the first real insect identification request that Daniel the Bugman has answered since last July when a personal matter added to the cumulative impact of the pandemic and caused Daniel to disconnect from the curious public.  We truly hope this is a sign that Daniel will return to daily What’s That Bug? postings.
This is a Giant Scale Insect in the genus Monophlebulus, and you may verify its identity on Project Noah. According to the Atlas of Living Australia:  “A slow moving wingless Hemiptera that feeds on plant sap. This Genus is found in Australia and South East Asia and is know to feed on Eucalyptus and Callistemon among other species. Some are colourful, beneath their white, waxy fluffy coating – including bright orange and blue. Some are as large as 25mm and even as adults they look rather like insect larvae. The females are wingless. Like some other mealybugs members of this Genus are occassionally tended by ants.”

Letter 8 – Mating Bird of Paradise Flies (Scale Insects) in Western Australia

Subject: Tree hopper – but WOW!
Location: College Grove (Bunbury), Western Australia
May 16, 2017 10:07 pm
Dear Bugman,
I live and work in Bunbury, Western Australia at a University campus in a natural bush setting. I have a favourite break-time perch on a fallen tree trunk, where for the past few months I have been noticing on occasion juvenile tree hoppers (possibly nymphs) climbing up the trunk of a nearby tree. I did not think to photograph them as they were – forgive me – rather plain looking. They had none of the lurid adornments of many hoppers (such as the ‘fluffy bums’), their tail end has two shortish spines which they carry erect.
Now that the rains have come, I have been noticing what may be an adult form of this hopper. It has the same colouration as the juvenile hoppers I was seeing. I have attached a photo of a single winged insect and what do you know, it has a spectacular tuft of white hair erupting from it’s backside, like I’ve seen in pictures of some nymphs of other hopper species! It is photographed on the trunk of the Banksia tree which I believe is the host plant. You can see that the insect’s colouration is a good match for the bark. They are not strong fliers, managing distances of only a metre or two at a time. They showed no interest in each other whenever they met by chance, which had me wondering if I was seeing represented only one sex.
I was not left wondering for long, as yesterday I found several of what appear to be the mature female form of the insect – and what an amazing creature she is! She is wingless and appears to fully retain her larval form, however is MANY times the size of the male. The specimen I photographed was making her way across damp leaf litter under the trees. Dwarfed by her enormous size, you can see three males on her back, which makes me think I’m definitely seeing male and female of the same species. I saw several specimens with males attached.
I am amazed that what I thought was a rather plain treehopper may be very unusual indeed – the extreme sexual dimorphism suggests the males and females have very different lifestyles, – ‘conventional’ hopper males in the treetops and giant larval females perhaps among the leaf litter. If I had not seen them together, I would never have imagined they were the same species. I have not been able to find any images online that are similar to my specimens, nor any indication that such dimorphism is common in hoppers. I am excited to have found such an unusual and seemingly undocumented insect.
What do you think, Bugman?
Signature: Glenn Brockman

Hi Glenn,
What we think is that your images are amazing, and that this is a really exciting posting for us, but these are NOT Treehoppers, but they are members of the same order Hemiptera.  We quickly identified the male Scale Insect as a Bird of Paradise Fly from the genus Callipappus, thanks to the Australian Museum site where it states:  “This genus includes some of the largest known scale insects in the world. The males and females look completely different. Males are delicate and exotic insects, whilst females are flightless grub-like insects.”  The site also states:  “Males have the front pair of wings well-developed for flying, with the hind pair of wings reduced, so that they look superficially like true flies in the order Diptera. The mouthparts are not functional, so the usual characteristic of the order Hemiptera (“sucking mouthparts”) is not visible. Males have long waxy filaments protruding from the tip of their abdomen, and when they fly they resemble dandelion seed heads. The wings and body are often coloured with vivid violet or red.  Adult females are large, up to 40mm long, often covered in waxy powder, and are usually found immobile and attached to vertical surfaces such as trees and fence posts.”  More information provided on Australian Museum states:  “Females moult into the adult stage and crawl up above ground and onto vertical structures such as trees and fence posts. Males mate with the females at this stage, then the females crawl to a protected place such as under bark, or in a crevice, where they become immobile and appear essentially dead. At this stage the four posterior segments of the abdomen are retracted into the abdomen to form a large cavity (“marsupium”), with a posterior slit-like opening. The first instar nymphs (“crawlers”) develop inside this marsupium in the dead leathery body of the mother, then emerge, dropping onto vegetation and soil. Mortality of these crawlers must be very high as 1,000 to 2,000 are produced per female.”  The site also states:  “Immature stages live underground on roots of plant hosts where they suck sap. Food plants are poorly known, as adult females often move away from nymphal feeding locations.”  You might have discovered that Banksia is a food plant.  The Bird of Paradise Fly and its mating habits are also profiled on the Brisbane Insect site where Violet Pheonix is listed as an alternate name and this information:  “The male has a small head and two black eyes, antenna are about the same length as it body. The male has only one pair of wings. We cannot see any sign of the second pair of wings. The wing veins are simple. They do not put down their wings when rest. We cannot see their mouth parts. The female is much larger than the male and is wingless. She has the flat and scout body with small eyes. She has the antenna about the same length as the male’s. She has three pairs of strong legs for climbing up the gum tree trunk. We believe they are going to lay eggs on the tree top.”  Thank you for contributing this marvelous addition to our site.

Letter 9 – Chinese Wax Scale on Sunflower

Subject:  Chinese Wax Scale found when cutting down last year’s sunflower stalks.
Geographic location of the bug:  Mount Washington, Los Angeles, California
Date: 03/20/2021
Time: 02:49 AM EDT
Several weeks ago, Daniel discovered these Scale Insects on the dried stalks of sunflowers and he left them in the front yard until he had an opportunity to identify them on the internet.  A visit to Alamy revealed the genus name Ceroplastes, and searching that on BugGuide revealed the Chinese Wax Scale.  According to BugGuide:  “eggs laid in chamber under body of adult” and “Non native. Introduced from Asia.”  Daniel threw them into the green recycle bin for garden materials after taking the image because he noticed the dreaded Argentine Ants taking an interest in the Scale and he suspects the Ants help to distribute the Scale nymphs to a new food plant.

Letter 10 – Cochineal Scale

what is this and how to control it
hi Bugman, I live in San Bernardino, CA, about an hour east of LA. I have a large outdoor cactus garden that has be come infested with something. It looks like a tiny piece of cotton and when squished, emits a purple goo. Someone thought they were mealy bugs but I’m not sure. I have sprayed them with rubbing alcohol and they just keep coming. They seem to suck juice from the cacti. They seem to attack mostly one type of cacti but recently moved to another type. any help is greatly appreciated.
Thomas McGovern

Hi Thomas,
The Cochineal Scale is often found on the pads of beavertail or opuntia cactus. If you decide not to eradicate them, you might choose to supplement your income by selling them. The purple goo you describe, according to Charles Hogue: “can be extracted by crushing dry specimens to a powder and then boiling it in water. this cochineal, or ‘Spanish Red’ as it is known, has been used for centuries as a dye by American Indians. It was discovered by the Spaniards during their conquest of the New world, and it quickly gained considerable commercial value as a crimson dye for textiles. Only with the advent of synthetic dyes has its importance subsided, although in recent years its use has been revived in the search for natural food colorings.”

Letter 11 – European Elm Scale

Flat oval brown/grey with white margin larva on elm in NH
Location: Concord, NH
May 29, 2011 1:19 am
Just discovered several 6 to 8 millimeter flat oval larva in clusters on young Elm tree in Concord, NH. We believe ants have been farming aphids on this tree in the past and we expect they are at it again. When I scraped the clusters they are soft and become an orange-red ink like (blood colored?) mass. They seem to have collected at regions where the bark is splitting as the tree grows and at sites of pruning last fall. One photo shows how they appear to have a fuzzy white margin.
Signature: Planting Trees for Shade.

Of the European Elm Scale, Gossyparia spuria, BugGuide indicates:  “Sap-sucking can cause stunted, chlorotic foliage, premature leaf drop and branch dieback. Associated black sooty mold growth from honeydew secretions on tops of branches gives trees an overall black appearance. Honeydew secretions are also a common nuisance to cars parked under infested elms.
Introduced from Europe.”  It seems the European Elm Scale is an Invasive Exotic species.

Letter 12 – Rose Scale

what is this??
i just noticed several of these on my rose bush, what the heck is it…it looks like an egg over-easy

You have Rose Scale, Aulacaspis rosae. According to Compton: “This species infests the stems of roses, blackberry, raspberry, dewberry, and some other plants. The infested stems often become densely coated with the scales. The scale of the female is circular, snowy white, with the exuviae light yellow and upon one side.” Your photo shows a solitary female. Get rid of her before she reproduces and infests your bushes.

Letter 13 – Scale Insects from the UK

Subject:  Elm scale?
Geographic location of the bug:  Brighton, UK
Date: 06/13/2018
Time: 03:08 AM EDT
Your letter to the bugman:  What is this bug?!
Is it a bug in cocoon form?
How you want your letter signed:  BugGirl

Dear BugGirl,
These are definitely Scale Insects, and we suspect you questioned if they are Elm Scale because they were found on an elm tree.  There is an image of Horse Chestnut Scales, Pulvinaria regalis, on the Bedfordshire Natural History Society site that looks very similar and this information is provided:  “This species probably originates in Asia, but has become widespread in central and northwest Europe since the 1960s. It is broadly polyphagous on woody plants. It is the most common coccid in urban areas throughout most of Britain but also occurs at low densities in rural areas. In Beds it has been found in Bedford, Bigglesworth, Caddington, Dunstable, Flitwick, Leighton Buzzard, Luton, Luton Hoo, Sandy, Swiss Cottage and Whipsnade; on bay laurel, elm, ivy, horse chestnut, lime, maple and sycamore.”

Letter 14 – Scale Insect from Honduras

Subject:  Ants protect it.
Geographic location of the bug:  Tegucigalpa, Honduras.
Date: 01/22/2018
Time: 04:30 PM EDT
Your letter to the bugman:  I found this “button” like thing, along with a few other attached to a chia stem. Ants seems to be feeding from them and protects them.
How you want your letter signed:  Quique.

Dear Quique,
We feel pretty confident this is a Scale Insect in the Hemiptera superfamily Coccoidea which includes Mealybugs as well as Scale Insects.  These are plant parasitic Hemipterans that are immobile as adults.  Like many other Hemipterans, including Aphids and many Hoppers, the Scale Insects exude a sweet “honeydew” that is attractive to Ants, so Ants often care for the Hemipterans.  Planet Natural has a nice posting regarding Scale Insects.

Letter 15 – Scale Insects

Subject: Tree bugs
Location: Sheffield
May 18, 2017 8:24 am
Can you please let me know what the bugs in the picture are.
Signature: Mal

Dear Mal,
These are Scale Insects, but we are uncertain of the species.  Knowing where Sheffield is located and knowing the type of tree would both make species identification much easier.

Letter 16 – Scale Insects on Dogwood

White bugs on my Dogwood
Location: Western Washington, Bellevue
August 7, 2011 5:59 pm
Hello Bugman!
Just wandering through my yard and noticed these little guys all over my dogwood and spreading to the cedar and apple next to it. Should I be concerned?
Signature: Thanks, John

Hi John,
You have Scale insects, and you should try to get rid of them.  We use a spray of soapy water on our plants to help eliminate Scale.

Letter 17 – Scale found on Woody Plant

It’s sticks to a surface very well and is not easy to detach
az-j

Dear az-j,
Though we have not had any luck locating any images that look exactly like the creature you submitted, we can’t imagine it is anything but a Scale Insect.  Beyond the Human Eye has some nice Scale Insect images.
Continued searching might have resulted in an identification.  Thankfully your situation has not escalated to this stage pictured on BugGuide of Chinese Wax Scale.  According to BugGuide the Chinese Wax Scale is  “Non native. Introduced from Asia.”

Letter 18 – Unknown Scale Insects on Spruce

Subject: Spruces with tiny scale on stem.
Location: Pennsylvania 19446
February 7, 2016 11:04 am
There is an area of several miles with Colarado Spruce and White Pine decline. The White Pines have Eriophyid Mites and Pine Oystershell scale. The Spruces also have Eriophyid Mites and a scale that looks smaller and different than spruce bud scale. Any ideas?
Signature: Chris

Dear Chris,
We have tried several times to find information on Scale Insects that attack spruce, but to no avail.  We could really use a Hemipteran expert to assist with this ID.

Letter 19 – Wax Scale

egg case?
not sure what this is, Noticed this today on a japanese maple in Memphis, Tennessee. Not even sure what to categorize it as. An egg case? It’s about a 1/2 inch in diameter.
Thanks,
Tim
I found the site below which identified the object as the casing around wax scale. I actually found about a dozen, which ranged from 1/8 of an inch to a little over 1/4 inch.
http://www.walterreeves.com/qa_display.phtml?qaID=957

Hi Tim,
Thanks for getting us an answer before we had a chance to do the research. We will also post a like to your site, www.wildlifetheater.com so you will get some additional traffic.