Examples from the Web for egg sac
Historical Examples of egg sac
In the specimen figured, the egg-sac was concealed in the upper part of the web.
In a spider's egg-sac the young after hatching do not immediately leave the sac, but remain in it for several days.Elementary Zoology, Second Edition
Vernon L. Kellogg
These eggs hatch early in the winter; but no spiders emerge from the egg-sac until the following spring.
One of the running spiders (Dolomedes) carries her egg-sac with her mandibles until the young are ready to emerge.