This orchid flower looks amazing, right? I think so, too. I can’t believe I found scale on this phalaenopsis orchid flower! It has been sitting on my kitchen table, greeting me every morning. I’ve had the plant for a while and it blooms reliably and is so beautiful. The battle is on! I will win this war against scale.
Imagine my surprise when I took it to the sink to water it and found these scales on the flowers! They weren’t obvious at all from the front of the flower but were obvious when I turned the plant around. There were big brown bumps on the flowers and I found a nymph, one of the earlier stages of development of the scale, on the flower stem.
Indicators You Have Scale
One of the most obvious indication you have scale is the presence of honeydew. Honeydew is a shiny, sticky substance excreted by the insect. YUCK! Since the sap they are eating is from the phloem it is a carbohydrate or sugar, which when it is excreted, is sticky.
Your plant can also have yellowing or speckled leaves or just an overall appearance of not doing well. Keep a close eye on your plants and learn to “read” the signs they are giving you about how they are doing.
What is this scale?
Soft brown scale and common shield scale are two of the common names for this scale, and its scientific name is Coccus hesperidum. It is an insect with piercing mouth parts that are used to suck the sap out of plants. It then excretes the honeydew discussed above. The female scale has three stages, two nymphal stages, and one adult. The nymph is pictured below and you can see it is a much lighter color than the adult scale pictured above. It is also much flatter than the adult which become more convex with age. When the eggs hatch, they are called crawlers because they crawl around and find a place to settle down, make their covering, and start damaging your plant.
Scale on flowers?
I was surprised after seeing the scale on the flowers, that there is no indication of scale on the plant itself. Believe me, I have experienced scale on phalaenopsis plants before. Maybe this was one of them and I thought I had removed all the scale and treated it long enough to keep them away. Maybe they had already crawled up the stem to the flowers because I have no other explanation. I have never seen scale on flowers before. I talked to my brother, who has a master’s degree in forestry and deals with plant pests every day, (yes a family of plant geeks) and he pointed out that because the scale is on an orchid flower, it had time to become an adult on a flower. Phalaenopsis orchid flowers last a long time, whereas other flowers are fleeting, not giving scale long enough to mature on the flower. Thanks for the “aha” moment, Keith!
The Plant and Control
As you can see below, this isn’t a shining example of a healthy orchid. It has marks on it, damaged brown tips, and more, but no scale is present. I looked everywhere and found none. After cutting the inflorescence off, I wiped down the entire plant with rubbing alcohol and rinsed it well. I will keep an eye on the plant to make sure no other insects appear. I also repotted it with fresh, clean potting mix, in case any crawlers were hiding in there. You may choose to spray your plant with a horticultural oil, Neem oil, an insecticide, or an insecticidal soap to kill any of the hatching eggs and crawlers. Consistency and close inspection often is the key to controling them.
Here are a few more tidbits of information about scale:
Scale are polyphagous, meaning they feed on multiple plants. I’ve found them on ferns, orchids, schefflera, and many more plants over the years.
Scale have a protective covering made of chitin and because insecticide and other controls don’t easily penetrate the covering, scale is hard to control. That is why it is a good idea to pick as many of the scale off as you can and be consistent checking the plant and removing any of the scale you see before treating it with a product to control them.
The color of the scale darkens as it matures. As you can see above the nymph is a light tan and the mature scale is dark brown.
Scale are multivoltine, meaning they have several broods of babies in a year. Yikes!
When scale are dead, they may stay attached to your plant. I scrape them away before treating the plant so I know when new ones appear.
On some websites, you will find they tell you to use malathion and diazinon insecticides to fight the scale. These chemicals have not been used since the early 2000s and are no longer available.
I hope you don’t encounter scale on your plants, but if you do, take immediate action to get rid of them, and first and foremost, move the infested plant away from any other plants. Use the safest treatment first (hand removal and alcohol) and work your way up to insecticides if necessary. If the plant is too heavily infested, it may be in your best interest (and your other plants’) to just throw the plant away. It’s okay.
Have a great week, plant friends.