The classical model of juvenile hormone (JH)-mediated wing polymorphism was proposed in the early 1960s, and numerous studies have tested this model using exogenous hormone treatment. However, this indirect method may yield misleading results, necessitating direct quantification of JH titers in insects. In this study, the effects of JH application on wing development and comparisons of hemolymph JH titers between presumptive long-winged (LW) and short-winged (SW) nymphs in the cricket Velarifictorus aspersus (Walker) are investigated. The results show that treatment of presumptive LW nymphs with high-dose JH III significantly decreases the percentage of macropterous individuals during the penultimate and first half of the last stadia, indicating that exogenous JH III can suppress wing development in V. aspersus and that the last two stadia are critical periods for wing determination. However, application of precocene to presumptive SW nymphs does not induce macropterizing effects, and JH III titers are not significantly higher in presumptive SW females than in presumptive LW females during the critical period of wing development. Therefore, this model may not be applicable to this species and the brachypterizing effects associated with JH application may be induced by affecting other innate factors rather than by direct JH titers in hemolymph.