Question: What are these pea-sized globs of white foam all over the stems of my rosemary plant? Should I be concerned? — Leslie H., Belen, NM
Answer: It sounds like you’re describing spittlebugs and I’ve been seeing them all over the place lately, too.
They’re inhabiting the two autumn sage plants at the front entry of our office at the NMSU Agricultural Science Center at Los Lunas. There are thousands of spittlebug species, some of which are commonly found in New Mexico on a variety of plants, including pines and shrubby junipers.
Dr. Carol Sutherland, NMSU Extension entomology specialist and NMDA state entomologist, explained spittlebugs’ unusual behavior and how they got their name:
“So called because they suck up lots of plant sap, only to poop out the rest of this rather nutrient-poor diet. However, they blow bubbles in this sugary substance which soon billows all over them, head to toe and beyond.
“This does wonders for their complexions, probably, but also may protect them from predators. Alternatively, that foamy wet suit may also reduce the impact of bright sunlight on their otherwise soft bodies.”
The same gunk that protects them from heat and predator stressors also happens to render insecticide sprays virtually useless. Luckily, they cause mostly minor aesthetic damage and can be either rinsed off with a water hose or ignored altogether. They also undergo only one generation per year.
In most cases, I recommend being wowed by them and let them be rather than trying to control infestations. To briefly summarize in the parlance of our times: “TL;DR. Bottom line, spittlebugs are NBD” (if you need a translation, ask a millennial).
Just last week I happened across the familiar spittlebug globs when vacationing near Asheville, N.C.. While touring an outrageously green garden, I snapped photos of them minding their own beeswax at the bases of penstemon leaves.
I’m always startled when I find organisms I’m used to seeing in New Mexico in extremely different climates. Asheville has an annual rainfall of about 50 inches and last year they got more than 80 inches in some places. Redbuds, yarrow, several salvia species, Mexican evening primrose, and my favorite euphorb, the blue spurge (Euphorbia myrsinites), are just a few of the plants that caught my eye because I recommend them all the time as being relatively low water plants that are good choices for our arid gardens.
I also visited the South Carolina coast on that trip. In the sand dunes, right on the beach of Sullivan’s Island, where I grew up, yellow prickly pear blossoms and blanketflowers were practically waving me down and begging for a photo op.
Plants that grow close to the coast make me wonder about salt stress — the breeze itself is salty in that area and it causes lots of metal rust issues. It’s likely that the bucketloads of precipitation wash the salts down in the sand profile, below the root zone. Like Western North Carolina, Sullivan’s Island also gets close to 50 inches of rain a year on average.
Perhaps these species are worth studying for their salt tolerance. The beachy species that also grow well in our desert could be recommended in gardens grown with non-potable, brackish or recycled water. These salty questions will have to wait for another week.
(Send gardening questions to Southwest Yard and Garden — Attn: Dr. Marisa Thompson at firstname.lastname@example.org, or at the Desert Blooms Facebook page (@NMDesertBlooms)
Please copy your County Extension Agent and indicate your county of residence when you submit your question!
For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.)