The Life Cycle of the Box-Tree Pyralid, Glyphodes perspectalis (WALKER) (Lepidoptera: Pyralidae): II. Developmental Characteristics of Larvae

The developmental characteristics of larvae of the box-tree pyralid, Glyphodes perspectalis (WALKER), were studied under various laboratory conditions with special reference to the number of instars and developmental period. When reared on the box-tree, Buxus microphylla, under continuous light conditions at 25°C, larvae developed continuously and had 6 instars, each lasting about 3 days except for the final instar (ca. 8 days). At 20°C, some larvae went through only 5 instars before pupation. However, when larvae were fed on other host plants, B. semipervirens and B. microphylla var. insularis, a few 7th instars appeared. At a photoperiod of 12L-12D, most larvae entered diapause at the 4th instar and a few did so at the 5th. More diapausing 5th instars were observed at 15°C or 25°C. The proportion of larvae entering diapause at the 5th instar increased with photoperiod at 20°C. Such individuals underwent a stationary molt in the cocoon and the shed head capsules were smaller than those of non-diapause larvae at the same instar. Overwintered larvae pupated after 3 or 4 ecdyses in the laboratory, suggesting that they had a total of 7 larval instars.