24 



THE BIOLOGY OF INSECTS 



inpushing of the skin at the mouth-region and consequently 

 lined with a chitinous layer which is an extension of the 

 outer cuticle. The details of structure of the gullet and 



Fig. 9. — Maxilla of an Owl Moth (Agrotis). c, cardo ; 5, stipes ; 

 p, palp (vestigial) ; g, long flexible galea with groove (gr) on its inner 

 face and coupling hooks and sensory organs towards its tip. X 50. 



crop differ — like those of the jaws — in insects that differ 

 in the nature of their food. Thus in a cockroach, earwig, 

 or beetle, which swallows smaller or larger solid lumps, the 



