yarn b eg a spun acrylic with a relatively large diameter 0 30 mm whereby is obtained in addition to the softness also provides a brake against step displacement in order to further enhance the softness of the material and then particularly in the folding direction of the material are thin hairy yarn c relatively loosely inlaid with a diameter of eg 0 15 mm the material in these hairy yarns is as well preferably acrylic but can even consist of pvc polyester or nylon these yarns are as well uv stabilized the conventional method to fasten the insect net 10 to control bars 16 is either by means of hooks which are hooked into the fabric and which by means of a loop shaped portion is displaceable along the control bars or by loop ribbons being sewn to the insect net just in front of the control bars 16 and through which loops the control bars are thread in the former case the hooks will deform the net so that so great openings are formed that insects can pass through these while in the other case the air permeability of the insect net is deteriorated besides such an insect net has to be prepared i e loop strings must be sewn which requires a manual operation which considerably rises the price of the net according to the invention in the fabric warp and or weft direction at some distance from each other control threads d have been inserted likewise of a hairy but in relation to the rest very rough yarn for example 1 mm in diameter and which control threads with even intervals form loops 19 through which the control bars 16 of the ventilator door.