If there's webbing amongst the leaves, my money's on box tree caterpillar, although its odd you've not actually noticed the caterpillars themselves yet. Of all the problems Box gets (and its an ever increasing list) the only one that goes with webbing is the caterpillar. The caterpillar is the larval stage of a moth and was first found in mainland Europe in 2007, so it's been around for a while, not quite so long in the UK as over there. Eggs are often present under the leaves if the caterpillars are not hatched yet, so check beneath.

This link https://www.rhs.org.uk/advice/profile?PID=88 lists various problems from which Box suffers - you can click on each one for more information to see for yourself what you think.If it is Box caterpillar, picking them off by hand is useful, but spraying may be required. Note the spray has to be pretty forceful in order to penetrate the webbing. Pesticide products recommended in the link may not be available under the same names where you are, but there should be products using the same active ingredients.

Not sure what those deposits are on the leaves in the bottom left picture, but I do know that other evidence of Box Tree Caterpillar/Moth is frass deposits and residues of moult such as 'black head capsules of different sizes'. Sounds charming - got that from this link here http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=118433 which has information that may be more pertinent to mainland Europe.

If there's webbing amongst the leaves, my money's on box tree caterpillar, although its odd you've not actually noticed the caterpillars themselves yet. Of all the problems Box gets (and its an ever increasing list) the only one that goes with webbing is the caterpillar. The caterpillar is the larval stage of a moth and was first found in mainland Europe in 2007, so it's been around for a while, not quite so long in the UK as over there. Eggs are often present under the leaves if the caterpillars are not hatched yet, so check beneath.

This link lists various problems from which Box suffers - you can click on each one for more information to see for yourself what you think.If it is Box caterpillar, picking them off by hand is useful, but spraying may be required. Note the spray has to be pretty forceful in order to penetrate the webbing. Pesticide products recommended in the link may not be available under the same names where you are, but there should be products using the same active ingredients.

Not sure what those deposits are on the leaves in the bottom left picture, but I do know that other evidence of Box Tree Caterpillar/Moth is frass deposits and residues of moult such as 'black head capsules of different sizes'. Sounds charming - got that from this link here: Plantwise Knowledge Bank which has information that may be more pertinent to mainland Europe.

If there's webbing amongst the leaves, my money's on box tree caterpillar, although its odd you've not actually noticed the caterpillars themselves yet. Of all the problems Box gets (and its an ever increasing list) the only one that goes with webbing is the caterpillar. The caterpillar is the larval stage of a moth and was first found in mainland Europe in 2007, so it's been around for a while, not quite so long in the UK as over there. Eggs are often present under the leaves if the caterpillars are not hatched yet, so check beneath.

This link https://www.rhs.org.uk/advice/profile?PID=88 lists various problems from which Box suffers - you can click on each one for more information to see for yourself what you think.If it is Box caterpillar, picking them off by hand is useful, but spraying may be required. Note the spray has to be pretty forceful in order to penetrate the webbing. Pesticide products recommended in the link may not be available under the same names where you are, but there should be products using the same active ingredients.

If there's webbing amongst the leaves, my money's on box tree caterpillar, although its odd you've not actually noticed the caterpillars themselves yet. Of all the problems Box gets (and its an ever increasing list) the only one that goes with webbing is the caterpillar. The caterpillar is the larval stage of a moth and was first found in mainland Europe in 2007, so it's been around for a while, not quite so long in the UK as over there. Eggs are often present under the leaves if the caterpillars are not hatched yet, so check beneath.

This link https://www.rhs.org.uk/advice/profile?PID=88 lists various problems from which Box suffers - you can click on each one for more information to see for yourself what you think.If it is Box caterpillar, picking them off by hand is useful, but spraying may be required. Note the spray has to be pretty forceful in order to penetrate the webbing. Pesticide products recommended in the link may not be available under the same names where you are, but there should be products using the same active ingredients.

Not sure what those deposits are on the leaves in the bottom left picture, but I do know that other evidence of Box Tree Caterpillar/Moth is frass deposits and residues of moult such as 'black head capsules of different sizes'. Sounds charming - got that from this link here http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=118433 which has information that may be more pertinent to mainland Europe.