PROBLEM TO BE SOLVED: To provide an insecticide solution which is used for thermal transpiration, can stably thermally be transpired for a long period, and can thereby sustain the stable insect pest-controlling effect for a long period. SOLUTION: This insecticide solution for the thermal transpiration comprises (a) a pyrethroid compound and (b) kerosene whose 95 wt.% or more has a distillation temperature of >270 deg.C on atmospheric pressure distillation and which has a sulfur content of <=0.5 wt.%, wherein the content of (a) is 0.01 to 20 wt.% and the content of (b) is 80 to 99.99 wt.%.
