Jane, Most likely the troublesome cutworms at your place are Noctua pronuba which go by various common names, among them greater yellow underwing,large yellow underwing, and the winter cutworm. This page shows the adult and displays the seasonality in the northwest. The bright orange of the hind wings is easily recognized when the moth suddenly flies out its daytime hiding place, commonly a clumping perennial or small shrub. Noctua comes is quite similar as an adult but the caterpillar is quite different than that of N. pronuba.) http://pnwmoths.biol.wwu.edu/browse/… The winter cutworm arrived in the northwest approx the year 2000. They overwinter as caterpillars. They typically feed at night during the fall, winter, and spring when temperatures are in the 40s or above. Thus, their damage is often attributed to slugs. You can differentiate the damage of these two pests by closely examining the edges of the holes in the leaves. Here, they specialized on my Pacific Coast iris hybrids, but they will also damage numerous other perennials, among them rhubarb leaves. This pub has excellent images which will help you ID the larvae. http://pestid.msu.edu/insects-and-arthropods/… As does this: https://ag.ndsu.edu/archive/entomology/… Also see bugguide: http://bugguide.net/node/view/9821/ Least-toxic management includes various techniques and, as you've commented, some make sense for individual pots/small plantings, others don't: - row covers - handpicking (at night, about 10:30 or so) then snip in half or put into soapy water - Btk (Bacillus thuringiensis kurstaki), which is specific to caterpillars, but is effective only when they are half-grown or younger. Mature specimens may be 2..5 inches long. Btk is available under several product names, among them Dipel, Thuricide, Caterpillar Killer, and more. (I suspect the cats are too old for this to be effective at this time; they will soon pupate and the moths will emerge in May.) Hope this helps, Jean from Portland,Oregon -----Original Message----- From: Jane McGary <janemcgary@earthlink.net> To: Pacific Bulb Society <pbs@lists.ibiblio.org> Sent: Sun, Mar 20, 2016 4:37 pm Subject: Re: [pbs] Cutworms and bulbs On 3/20/2016 3:37 PM, Diane Whitehead wrote: > When do these moths lay their eggs? Maybe some nets or screens could keep them out of your greenhouse. > > I should have mentioned that the "greenhouse" is 20 by 40 feet and the sides are hardware cloth (wire mesh), not solid. I don't know if the moths can get through the mesh but they might get in under the roof or some other unprotected place. Juncos (small birds) sometimes get in; I suspect they walk between the bottom of the door and the gravel path. The protected situation also attracts many spiders, which may help control the moths. Most advice on controlling cutworms in the home garden involves making little cardboard collars and putting them around the young plants. That is probably fine for somebody who is growing a dozen little plants -- not a thousand. Jane McGary Portland, Oregon, USA
