- Author: Ben Faber
This article was first posted in July of 2020 when it wasn't clear what this leaf roller/leaf miner was going to do. In the last couple of weeks I have heard from two PCAs from Ventura saying that they are having to spray for it. So, it is back and it is probabl6y going to hang around for a while. It does not seem to feed on fruit. It causes damage to leaves but it doesn't seem to be significant on mature trees. On a newly planted tree, it can defoliate it, so it should not be neglected. Read the history below.
A new pest for avocado? Old pest? How much damage will it do? Don't know yet.
Tracy Ellis, the San Diego County Ag Commissioner Entomologist has partially identified what appeared to be two pest and a parasitoid, as only one pest and a beneficial that is doing it's duty going after the pest.
The insect determination has come back for both larvae (one a leaf miner and one a leaf roller) as the same insect! It has been determined to be C-rated gracillariid miner Caloptilia sp. (Lepidoptera: Gracillariidae) at this time. An image of the adult moth is not yet available.
Apparently, the larval stage transitions from a miner to a roller, in what's called hyper-metamorphosis. Starting as a miner and abandoning the mine to roll the leaf. CDFA scientist Marc Epstein is taking a closer look at this insect . Marc does not know if it is a local insect that adapted to avocados or is an import, as many in this family have not been studied or sequenced.
The leaf roller/folder has appeared down in San Diego and Santa Barbara. It's not clear whether it will be a pest of the fruit at this time.
The results for the parasite came back as Hymenoptera. That too needs greater study.
Above is a photo of both insect stages. They can be found together in the same habitat.
The damage from the leaf miner generally looks like this
And miner looks like this
The damage from the leafroller looks like this:
Larval leafroller with the parasite on it.
And the parasite , once it grows up from being a maggot, looks like this
It's still not clear what damage this might do. Maybe nothing significant. Maybe this is an aberration only for this year. Stay tuned.