DEAR JOAN: I read about the hummingbird moth and its associated tomato hornworm in your column, so I thought I’d share a picture of a hornworm that was on my grape plants last year.
It was brown and I had never seen one of this color. By the way, I left it alone and let it munch away on the grape leaves.
David Boatwright
Bay Area
DEAR DAVID: Your tawny caterpillar, which looks just like a tomato hornworm save the color, was an Achemon sphinx. It eventually turned into a large and stunning light pink and brown moth. You may not have minded it on your grapevines, but the caterpillar can be destructive in commercial vineyards. A large caterpillar can eat nine grape leaves in a single day, and during heavy infestations, up to 500 may be found on a single vine.
Even with that, the Achemon is considered only a minor pest, largely because heavy infestations are cyclical. Infestations can be heavy for a few years, then very light for the next few.
While you may spot the caterpillar on your cultivated grape vines, wild grapes and Virginia creeper, the moth is much harder to spot. It flies only at night, drinking the nectar from petunias, honeysuckles, mock oranges and phlox. The female moth lays her eggs on the upper surfaces of older leaves, and the caterpillars burrow into the soil to pupate. The moths emerge in early spring.
The Achemon is one of three main pollinators for Platanthera praeclara, a rare and threatened orchid also known as the Great Plains white fringed orchid. It’s interesting how one creature can do so much damage to one plant and yet be so necessary to the survival of another.
DEAR JOAN: Why are the birds ignoring my thistle feeder? I used to have as many as a dozen goldfinches and nut hatches clamoring for space on my thistle feeder, but for several years now it is ignored.
I have tried replacing the sacks with new ones, to no avail. The birds do come to a feeder hanging nearby with seed.
Am I just wasting money buying Niger seed? I know others who have had the same problem.
Janey
Oakland
DEAR JANEY: There are several explanations.
The first and most likely is that the birds simply don’t have a taste for Niger.
Niger tends to be more popular in the winter, when birds may benefit more from the oil in the seeds. In the spring, their tastes turn more to seeds.
Another explanation could be the Niger itself. It is an imported product and it must be sterilized before crossing our borders. Some people believe the process has made the seed less appealing to the birds.
One thing we know for sure is that birds won’t eat stale Niger. Fresh seed will be a deep black color and shiny from the oil. Even newly opened bags may be old if the Niger has been sitting on store shelves for a long time. It’s best to buy from a store that specializes in wild birds. Their inventory turns over more quickly and they stock premium seed.
If the seed gets wet from rain or sprinklers, dump it immediately. It will quickly mold and can sicken the birds.
If none of these suggestions apply to your situation, then I wouldn’t spend money on any more Niger.
Try again in the fall and see how it goes.
Contact Joan Morris at jmorris@bayareanewsgroup.com. Follow her at Twitter.com/AskJoanMorris.
