Sensilla chaetica
The sensilla chaetica of the adult mandibular palpus has two subtypes (SCh IV, SCh V). SCh IV is found on segments 2, 3 and 4 of the mandibular palpus, while SCh V is found on segments 2 and 3 of the mandibular palpus. These two inductor subtypes differ considerably in length and basal width (Table 5).
The lengths of SCh V and SCh IV of the female mandibular palpus were both longer than those of the males, but there were no significant differences in width. Quantitatively, females outnumbered males only in SCh IV (♀ = 226.98 ± 12.67 μm, ♂ = 81.31 ± 4.93 μm, t = 10.71,P < 0.01) in segment 4 of the mandibular palpus, whereas males outnumbered females in SCh IV (♀ = 321.60 ± 1.21, ♂ = 24.60 ± 1.47, t = 7.58, P < 0.01), and SCh V (♀ = 22.00 ± 2.79, ♂ = 48.60 ± 4.12, t = -5.35, P < 0.01) were significantly more numerous in males than in females, and SCh IV (♀ = 193.60 ± 6.52, ♂ = 226.60 ± 5.84, t = -3.77, P< 0.05) and SCh V (♀ = 14.80 ± 3.38, ♂ = 31.60 ± 1.44,t = -4.57, P < 0.01) in segment 3 of the mandibular palpus were significantly more numerous in males than in females. Böhm’s bristle sensor (Bb) also occurred at the junction of the base of the first segment with the mouthparts. There were no significant numerical differences in Bb between males and females in the labial palpus and mandibular palpus as a whole (Fig. 5).