The nervous system is remarkably concentrated in some beetles, the abdominal ganglia showing a tendency to become shifted forward and crowded together, and in certain chafers all the thoracic and abdominal ganglia are fused into a single nervecentre situated in the thorax, - a degree of specialization only matched in the insectan class among the Hemiptera and some muscid flies.
The number of limb-bearing somites in the insectan head is thus seen to be seven.
The legs of Hymenoptera are of the typical insectan form, and the foot is usually composed of five segments.
The number of tarsal segments is reduced; often three, two or only one may be present instead of the typical insectan number five.
The typical insectan ovipositor with its three pairs of processes, one pair belonging to the eighth and two pairs to the ninth abdominal segment, can be distinguished in the female.