Figures 3.6


The central nervous system of various insects showing the diversity of arrangement of ganglia in the ventral nerve cord.
Figures 3.6. The central nervous system of various insects showing the diversity of arrangement of ganglia in the ventral nerve cord.

Varying degrees of fusion of ganglia occur from the least to the most specialized: (a) three separate thoracic and eight abdominal ganglia, as in Dictyopterus (Coleoptera: Lycidae) and Pulex (Siphonaptera: Pulicidae); (b) three thoracic and six abdominal, as in Blatta (Blattodea: Blattidae) and Chironomus (Diptera: Chironomidae); (c) two thoracic and considerable abdominal fusion of ganglia, as in Crabro and Eucera (Hymenoptera: Crabronidae and Anthophoridae); (d) highly fused with one thoracic and no abdominal ganglia, as in Musca , Calliphora, and Lucilia ( Diptera: Muscidae and Calliphoridae); (e) extreme fusion with no separate suboesophageal ganglion, as in Hydrometra (Hemiptera: Hydrometridae) and Rhizotrogus (Scarabaeidae). (After Horridge 1965)

Previous figure
  Diagram of a simple reflex mechanism of an insect.
Next figure
  Mediolongitudinal section of an immature cockroach of Periplaneta americana (Blattodea: Blattidae) showing internal organs and tissues.