|Box caterpillar only eats boxes
Box caterpillar has now made several appearances in the UK and gardeners might wonder whether a completely defoliated box will ever recover.
Brenda’s son so suffered in Summer 2015 in France. My article about box caterpillar control in his garden is here.
Although Peter claims to have sprayed again after my 2015 visit I doubt it. For reasons it’s best not to go into most of the hedge had been completely neglected for two years during their temporary absence.
The box caterpillar has now completely gone. My 2017 pictures below illustrate the hedges’ recovery - or otherwise. It is a ‘natural experiment’ which might be of interest!
|The small hedge at the front of the house was completely killed. Contrast the healthy euonymus hedge
|Two years after - how long can you wait?
|Peter was quoted an exorbitant amount for its removal. He is going to be busy with his chainsaw! There is no read to dig out the roots
|This is completely recovered and is ready for clipping
|I failed to take a picture of the hedge completely smothered by this climbing weed. Not the way to recovery
|The box tree is now completely unscathed and the box hedge on the left badly needs cutting
Wondering what happened
The key questions I ponder is why box caterpillar has completely gone and never returned (well, not yet) and why in different parts of the garden recovery has been everything between complete and totally absent. All the box had been completely defoliated in 2015
As to recovery - it’s taking a while. The hedge that has completely died is the small one which was completely exposed to intense Toulouse summer sunshine. In the absence of leaves and their evaporative cooling the exposed twigs would have been very warm. Perhaps the high ratio of surface area to volume in small things was significant. Or perhaps a small hedge had less stored resources than a large one.
What ever the reason it does appear that the larger the box plants the greater the recovery. I think I also discern greater recovery where plants were in a less open position. Perhaps open sites were more exposed to the moths?
I had expected that if the hedge was not re-sprayed surviving caterpillars would complete their lifecycle and there would be further damage later that season and in the following year. It does not seem to have happened. Perhaps the next generation lacking food resources on a decimated plant is programmed to fly elsewhere?
I had also expected there would be further invasion of moths in the following year. This has not happened and the living hedges continue their recovery. For some very slowly.
This post explains why I would not dig out the stumps
Final Report on Peter’s box Hedge June 2018
We returned to France two years later and found our efforts had been in vain. I can only presume that a further infection of caterpillar returned - either from a further invasion or emergence of a new generation from pupae.Certainly Peter confirms he neglected to respray.
This theory is not a given. It is a possibility that the further stress of a hot Summer and continued neglect such as failure to water was what finished them off!
The smallest hedges had already been thought dead. All the larger hedges are now completely brown. A few have few green shoots if you cut all the way back to the trunk and in theory could be saved.
Some hope of that happening now and in any case recovery would take a few years. Should anyone in a similar situation try I would suggest partial removal of dead shoots to let light penetrate through. Only at first partial as complete exposure of delicate green shoots to hot sun might be in itself fatal.
The only good news from France is that Peter’s 20 foot box tree is now pinky and perky and strongly growing away. This confirms the theory that the larger and stronger the box the greater the chances of recovery from a box caterpillar infection
Although Peter must hang his shame over this sad story at least he came up with a wheeze to speedily pull out the dead hedge.