Total and differential haemocyte counts following starvation and feeding resumption, ventral nerve cord transection, and brain implantation followed by methoprene application and 20-hydroxyecdysone injection were studied in Danaus chrysippus (Linnaeus) larvae. The results revealed that initial starvation and transection of the ventral nerve cord before the fifth abdominal ganglion in fifth instars of D. chrysippus led to a reduced total haemocyte count, on the one hand, and to a higher variation in percentage of different haemocyte types, on the other. While feeding resumption, brain implantation and 20-hydroxyecdysone treatments reversed the effect of starvation and nerve cord transection, methoprene application produced a decline in total number of haemolymph cells.

Nerve cord sectioning in the early fifth instar larva of Papilio demoleus inhibited or delayed pupation depending on the site of sectioning. This seems to be due to interruption in the feeding leading to interruption in the proprioceptive input reaching the brain. Sectioning of the peripheral nerves N5 and N8 prevented shortening (condensation) of the thoracic segment of the ventral nerve cord in the adult. Sectioning of these and other nerves, however, had no effect on the developmental events.