Insect screen with a driving device of a net guiding chain and a system for facilitating assembly and for correcting the positioning arrangement, said insect screen comprising: a) a vertical box lateral with respect to an upper guide, the latter when installed being orthogonal to the box, wherein said box contains at least part of a protection net, the latter being with one end anchored inside the box if of the pleaded type, or said protection net being joined with one end to a winding roller if of the winding type; b) a vertical handlebar to which the second end of the protection net is joined, the handlebar being with the upper end constrained to the upper guide placed in an operative condition and in a backing condition with respect to an engagement track anchored to the lintel of an opening of a building, said handlebar being movable longitudinally with respect to said upper guide; c) a net guiding chain with a seat for containing a lower profile of the protection net; the net guiding chain being made up of modules interconnected with each other, wherein said net guiding chain is with one first end engaged to the lower end of the box, while the second end slides inside the handlebar; d) a driving device of the net guiding chain, made up at least of cables and related transmission means placed at least inside the handlebar and the upper guide, wherein said insect screen is characterised in that it comprises a head associated with the upper end of the box to which head the upper guide is hinged, said upper guide being able to be moved at least from a condition in which it can be placed parallel to the box to a condition in which it can be placed orthogonal to the box. a) a vertical box lateral with respect to an upper guide, the latter when installed being orthogonal to the box, wherein said box contains at least part of a protection net, the latter being with one end anchored inside the box if of the pleaded type, or said protection net being joined with one end to a winding roller if of the winding type; b) a vertical handlebar to which the second end of the protection net is joined, the handlebar being with the upper end constrained to the upper guide placed in an operative condition and in a backing condition with respect to an engagement track anchored to the lintel of an opening of a building, said handlebar being movable longitudinally with respect to said upper guide; c) a net guiding chain with a seat for containing a lower profile of the protection net; the net guiding chain being made up of modules interconnected with each other, wherein said net guiding chain is with one first end engaged to the lower end of the box, while the second end slides inside the handlebar; d) a driving device of the net guiding chain, made up at least of cables and related transmission means placed at least inside the handlebar and the upper guide, wherein said insect screen is characterised in that it comprises a head associated with the upper end of the box to which head the upper guide is hinged, said upper guide being able to be moved at least from a condition in which it can be placed parallel to the box to a condition in which it can be placed orthogonal to the box.