Urgent insecticide advice please

[theedgeofthecloud]

Hello. Neighbours and us have a long low hedge between us. It's their boundary. The hedge has died and neighbour has discovered that it's because of box caterpillar. She came round last night and said the plan is to spray it today to see if that will kill off the infestation. I've been mulling overnight and am uneasy about how the insecticide is going to penetrate the soil our side of the hedge, and beyond. We have flowers, shrubs and also some fruit bushes there that we eat from. She's really nice, and it is her boundary, and I don't want to cause a rumpus. Is there any way I can protect our side from the spray or the residue? Or might there be a less harmful method she could use that I could recommend? I'm not green fingered at all and just a potterer in our garden. But we do like to avoid chemicals.

Any advice gratefully received. Thanks wise gardeners of Mumsnet.

If the hedge has died, surely it should just be removed? Spraying it with insecticide isn't going to revive it.

Thanks for your response. I think the feeling is there is the potential of a last hurrah. The leaf is mostly brown, but a bit of green growth remains. Sorry, not an experienced gardener but that is what I think they are thinking.

There are very few insecticides now that are residual. Best to apply early morning or late evening to minimise the impact on bees.

Many thanks onesmall. That's reassuring.

Neighbour has sprayed but the caterpillars are holding firm, so the hedge is unfortunately being incinerated this weekend . She used something called Bug Clear and said it's non harmful to fruit, flowers and pets.

Thanks for responses.