ers put in
the little rooms beside the eggs.

"Mrs. Polistes is a cousin of Mrs. Vespa. She is long and slender, while
Mrs. Vespa is rather broad. Her house is a much simpler affair. It has
just one layer of rooms suspended by a stem from the under side of a
porch, or maybe the eaves, of a house."

"Are there solitary wasps," asked Jimmie, "just as there are solitary
bees?"

"Many wasps prefer to live alone rather than in a big house with
hundreds of others. They are like bees in their cleverness, knowing how
to tunnel in wood, dig deep pits in the ground, or make nests of mud.
Mr. Kellogg, a very wise man, and young to be so wise, tells of one
interesting little wasp, called the thread-waisted sand-digger, which
lives in California in the salt-marshes. These marshes are covered by
plants, but in between are little smooth places covered with a
glistening crust of salt. It is in these open spots that Mrs.
Sand-Digger makes her home. She has strong jaws, and with these she cuts
out a neat little circle of salty crust. Then she begins to dig a
tunnel, humming away to herself all the time. After the hole is ready
she very carefully backs out of it and puts a circular door on.

"Then she flies away to find food to store up for her children. These
babies like tender, green inch-worms, so Mrs. Digger-Wasp hunts around
until she finds a fat one, and then proceeds to paralyze it, so that it
will stay quietly in the house until the babies are ready to eat it, for
baby digger-wasps are little cannibals, preferring living caterpillars
to any pre-digested spiders or flies. It is very wonderful that Mrs.
Digger-Wasp knows where to sting a caterpillar in order to paralyze it
and yet not kill it. But she does. Perhaps you remember that insects
have knots of nerve cells, connected by nerve threads, extending from
one end of the body to the other? Jimmie remembers that I pinched him to
illustrate this point. The knot on the top of the food-tubes is the
brain, then underneath there are usually three in the thorax and several
in the abdomen. Well, Mrs. Digger-Wasp stings one or more of these
little knots, which we call ganglia. That paralyzes the young inch-worm,
so that it becomes limp and helpless, but still lives. Then Mrs. Wasp
picks it up and carries it to her house, and packs it in the bottom of
the tunnel.

"After putting in five or ten she lays an egg, fastening it on the body
of one of the worms. She backs out of the tunnel,