is this red mite or fertilizer deficiency ??

Give micro nutrient zn mg b and fungiside

Hi Wasim ,Melon Fruit Fly ...click the above link for more details

Wasim CUCUMBER FLOWER DROP IN CONTROLLED CULTIVATION REASONS 1 Much difference between day & night temperatures 2 Cloudy environment 3 High temperature 4 High Humidity 5 High transpiration rate 6 Boron deficiency 7 Low phosphorus level 8 Water scarcity 9 Sucking pests especially thrips attack REMEDY 1 Use silicon to suppress environmental stress 2 Install foggers on western side (outer side) & mist spray should be on insect net 3 Give 400 gm Boran per acre at weekly interval 4 In calcareous soils dissolve Boran in Luke warm water & than supply through drip 5 Give Phosphorus (12:61:00 or 13:40:13 or 00:52:34) at 4 days interval in flowering stage 6 In winter give irrigation in early morning hours. 7 Spray 10 PPM NAA in severe cases 8 Use silicon base sticker & spreader like silwet in every spray 9 For controlling thrips use Fipronil, Lambda Cylohythrin or Thiomethoxim or Spinosad 10 Install cooling fans in summers  11 Avoid over watering in Rainy & winter as Fusarium wilt is the major threat in these seasons.