Zhang, Y., Xie, Y.P., Xue, J., & Liu, W. 2009 Developmental Variation in the Dermal Glands and Wax Secretions of the Mealybug, Phenacoccus fraxinus (Hemiptera: Coccoidea: Pseudococcidae).. Journal of Entomological Science 44(1): 59-68

Notes: Abstract A microscopic study of the dermal glands and wax secretions of the mealybug Phenacoccus fraxinus Tang demonstrated that the type, structure, size, quantity and distribution of dermal glands varied with life stage. These variations resulted in different quantities and morphology of waxy secretions with development. The apertures of the trilocular pores were initially small, irregular narrow seams on 1st instars. By the 3rd nymphal stage, these apertures were large and figure-8 shaped. Slender wax filaments were produced in the 1St stage, whereas wax filaments produced in the a= stage had an indentation along the middle. These tilocular pores were distributed on the dorsum and the venter of both stages, corresponding to the shape of the aperture. Quinquilocular pores were characterized by a thick rim and were scattered on the ventral surface, but these were not distributed in spiracle furrows as observed with other scale insects. Tubular ducts were composed of 2 layers-outer and inner ductiles-that resulted in the wax secreted from them being long, hollow filaments that served as a framework for the cocoon and ovisac structures. Wax production from these tubular ducts occurred at two distinct times during development. One occurred in late autumn and was produced by the older 2nd -instar nymphs. These waxy filaments were used to construct cocoons for the overwintering mealybugs. The other event occurred in early summer with adult females. These filaments were used to construct the ovisac. During other times of the year, these tubular ducts produced no additional wax.