FIELD: organic chemistry, insecticides. SUBSTANCE: invention relates to a novel crystalline D modification of dicyclanyl (2-cyclopropylamino-4,6-diaminopyrimidine- -5-carbonitrile) of the formula (I) 
. Dicyclanyl exhibits insecticide activity and develops growth-regulating activity with respect to insects. Crystalline D modification of dicyclanyl is used for preparing veterinary medicinal agent designated for control of extoparasites in domestic and agriculture animals. Indicated D modification of dicyclanyl exhibits indices obtained by method of differential scanning calorimetry, shows capacity for transformation in the range of temperatures from 150 C to 166 C at the heating rate 10 C/min and characterized by the following specific distances between crystalline lattice planes (in 
) determined by X-ray diffraction analysis using copper-Kα as a source of X-radiation: 11.4 ± 0.2; 8.7 ± 0.2; 7.1 ± 0.2; 5.92 ± 0.05; 5.75 ± 0.05; 5.70 ± 0.05; 4.45 ± 0.05; 4.40 ± 0.05; 4.15 ± 0.05; 3.96 ± 0.05; 3.94 ± 0.05; 3.80 ± 0.05; 3.78 ± 0.05; 3.72 ± 0.05; 3.53 ± 0.05; 3.41 ± 0.05; 3.32 ± 0.05; 2.96 ± 0.05; 2.92 ± 0.05; 2.84 ± 0.05 and 2.83 ± 0.05. Method for preparing crystalline modification involves at least one stage of process where suspension of compound of the formula (I) with the known or unknown either nonspecific morphological structure with grains size from 0.4 to 6 mcm is kept at temperature from about 30 C to 60 C but preferably from about 35 C to 50 C in 1-octanol or 1,2-propanediol or their mixture with water. Veterinary composition eliciting insecticide activity useful for control of ectoparasites in domestic and agricultural animals comprises crystalline D modification of dicyclanyl in solid form. EFFECT: improved preparing method, valuable properties of composition. 7 cl, 8 tbl, 8 ex
