The extent of each movement upwards is approximately determined by the depth of the perforation.
The apertures are arranged in a straight line when their number is not very large.

Why, indeed, should the insect wander to right or to left upon a twig which presents the same surface all over?
A lover of the sun, she chooses that side of the twig which is most exposed to it.

So long as she feels the heat, her supreme joy, upon her back, she will take good care not to change the position which she finds so delightful for another in which the sun would fall upon her less directly.
The process of depositing the eggs is a lengthy one when it is carried out entirely on the same twig.

Counting ten minutes for each egg-chamber, the full series of forty would represent a period of six or seven hours.

The sun will of course move through a considerable distance before the Cigale can finish her work.