Posted October 20, 2007
I learned from Dr. Elizabeth Boyd that the wood-boring worms associated with vine mealybugs are not clear-winged moths, as formerly supposed, but instead are in the family Cossidae. They have been identified as the genus Givira, but the species is not yet certain. Here is a picture of the adult of Givira arbeloides.
Dr. Boyd also told me that the life cycle of Cossid larvae is typically long, sometimes a year or longer. She is rearing out worms to adults using artificial diet. She has found a few parasitized VMB inside the tunnels, but only near the opening.
I have edited the previous remarks by changing "clear-winged moth" to "Givira moth".
Posted: Sat Mar 18, 2006 8:44 pm Post subject: Givira moth & vine mealybugs
During his talk at the AAIE meeting, Kris Tollerup mentioned that the wood-boring larvae of Givira moths are often found with vine mealybugs.
I've been seeing a lot of that in the area around Sanger and Parlier. The caterpillars appear to be attracted to the sugar around the mealybugs. For their part, the mealybugs like to locate inside the holes dug by the caterpillars. Presumably, the holes provide nearer access to the cambium layer.
I am currently finding all sizes of caterpillars and all sizes of mealybugs in the holes. On some vines, it seems the majority of mealybugs are in the holes, which are deep under the bark and not exposed to chemical treatment.
Even though some vines have a lot of wood-boring caterpillars, I doubt if the damage to the vine is economic. Which is good, because I don't know of any way to control them.
On the other hand, if the holes allow the mealybugs to stay longer under the bark, that could make mealybug control more difficult.
In this picture the caterpillar is peeking out of the hole, and several mealybugs can be also be seen.
Devin Carroll
Posted: Sun Mar 19, 2006 5:56 pm Post subject: No parasites in holes
We have been reporting about the Givira moth with VMB for the past four years. We've seen it reach very high population in older raisin vineyards in the Del Rey area.
As we reported in the past CTGC reports and at grower meetings, we have NEVER found a parasitized VMB in a Givira burrow - so we assume that there some protection for the VMB in this association. As we don't see honeydew accumulating in the burrow, we assume also that the moth larvae are benefiting as well.
Kent Daane