MR. NEWPORT ON THE NERVOUS SYSTEM OP THE SPHINX LIGUSTRI. 393 



Such is the state of the nervous system at the period antecedent to the development 

 of the perfect insect, which usually takes place about the middle or latter end of June. 

 The time which the Sphinx ligustri remains in the pupa state is thus shown to be at 

 least forty-two or forty-three weeks, as nearly as we are able to ascertain, since 

 owing to the eggs not being all deposited in the same week or month, and conse- 

 quently the larva not produced at exactly the same time, some broods are two, three, 

 or even four weeks later than others. 



A few days before the insect is ready to burst from the pupa-case, it becomes ex- 

 ceedingly restless and active, and writhes and turns in its cell repeatedly. That cell — 

 the little hermitage it had constructed in the earth with much assiduity in the pre- 

 ceding autumn, by moistening the soil that was to form the inclosing walls with 

 fluid from its silk- bags, and smoothing and moulding it into shape by rolling and 

 turning its body while the material was yet in a moist condition, and afterwards 

 lining the whole interior with a tissue of silky hangings— is no longer necessary to 

 protect the feeble and delicate pupa from the intrusion of enemies. The insect is 

 now vigorous, and its hard coriaceous covering being scarcely susceptible of injury, 

 it makes a powerful effort to force the walls of its cell, and emerge from its subter- 

 ranean abode. It gradually works its way upwards to the surface of the ground by 

 repeated contortions of its abdominal segments, assisted by the pointed extension of 

 the twelfth segment of the pupa-case, which serves as a lever against which the power 

 of the insect is exerted. The depth in the ground at which the cell is situated is 

 generally from six to eight inches, very rarely more, so that the insect has not far to 

 travel. But it does not all at once arrive at the surface ; its progress is slow and 

 gradual until within a short time before it is ready to burst forth, which is generally 

 in the early part of the day. 



During the three days preceding its actual appearance, an alteration, which has 

 for some time been taking place in the exterior of the pupa-case, becomes very 

 evident. The coverings of the eyes, of the antennae, the legs, and the wings are more 

 convex and prominent, particularly of the latter, which extend on each side the 

 thorax; and the union of the sutures of the approximated coverings of the limbs ap- 

 pear as if about to separate. A few hours previously to the liberation of the insect the 

 coverings of the wings lose their solidity, and upon slight pressure are elastic and 

 yielding, like dried membrane. This is also the case with other parts of the body, 

 but in a much less degree ; while the abdominal segments are elongated beyond their 

 original extent. This occurs from the abdominal portion being the first part of the 

 insect that is entirely freed from its attachment within the pupa-case. After this the 

 thoracic portion of the pupa-case becomes fissured along its dorsal line, as well as 

 transversely, behind the head and second segment, and the new-born insect gradually 

 pressing itself through the opening, and carefully withdrawing its limbs from their 

 respective coverings, comes forth with its wings rumpled and small, as if atrophied, 

 but like its whole body completely covered with scales. The insect immediately seeks 



