THE MASON-BEES

At a school where I once taught, one subject in particular appealed to both master and pupils. This was open-air geometry, practical surveying. When May came, once every week we left the gloomy schoolroom for the fields. It was a regular holiday. We did our surveying on an untilled plain, covered with flowering thyme and rounded pebbles. There was room there for making every sort of triangle or polygon.

Well, from the very first day, my attention was attracted by something suspicious. If I sent one of the boys to plant a stake, I would see him stop frequently on his way, bend down, stand up again, look about and stoop once more, neglecting his straight line and his signals. Another, who was told to pick up the arrows, would forget and take up a pebble instead; and a third, instead of measuring angles, would crumble a clod of earth between his fingers.

Most of them were caught licking a bit of straw. The surveying suffered. What could the mystery be?

I inquired; and everything was explained. The scholars had known for a long time what the master had not yet heard of, namely, that there was a big black Bee who made clay nests on the pebbles in the fields. These nests contained honey; and my surveyors used to open them and empty the cells with a straw. The honey, although rather strong-flavored, was most acceptable. I grew fond of it myself, and joined the nest-hunters, putting off the lesson until later. It was thus that I first made the acquaintance of the Mason-bee.

The Bee herself is a magnificent insect, with dark-violet wings and a black-velvet dress. We have two kinds of Mason-bees in our district: this one, who builds by herself on walls or pebbles, and the Sicilian Mason-bee, who builds in colonies under sheds and roofs. Both use the same kind of material: hard clay, mixed with a little sand and kneaded into a paste with the Bee’s own saliva, forming, when dry, a sort of hard cement.

Man’s masonry is formed of stones laid one above the other and cemented together with lime. The Mason-bee’s work can bear comparison with ours. Instead of stones, she uses big pieces of gravel. She chooses them carefully one by one, picks out the hardest bits, generally with corners, which, fitting one into the other, make a solid whole. She holds them together with layers of her mortar, sparingly applied. Thus the outside of her cell looks like a rough stone house; but the inside, which must be smooth in order not to hurt the Bee-baby’s tender skin, is covered with a coat of pure mortar. This inner whitewash, however, is not put on artistically, but in great splashes; and the grub takes care, after it has finished eating its honey, to make itself a cocoon and hang the walls of its room with silk.

When the cell is finished, the Bee at once sets to work to provide food for it. The flowers round about, especially those of the yellow broom, which in May deck the pebbly borders of the mountain streams with gold, supply her with sugary liquid and pollen. She comes with her crop swollen with honey and her body yellowed underneath with pollen-dust. She dives headfirst into the cell; and for a few moments you see her jerk violently as she empties her crop of the honey-sirup. Afterwards, she comes out of the cell, only to go in again at once, but this time backwards. The Bee now brushes the lower side of her abdomen with her two hind-legs and rids herself of her load of pollen. Once more she comes out and once more goes in headfirst. It is a question of stirring the materials, with her jaws for a spoon, and making the whole into a smooth mixture. She does not do this after every journey; only once in a while, when she has gathered a good deal of food.

When the cell is half full of food, she thinks there is enough. An egg must now be laid on top of the paste and the house must be closed. All this is done quickly. The cover is a lid of pure mortar, which the Bee builds by degrees, working from the outside to the center. Two days at most appeared to me to be enough for everything, provided that no bad weather—rain or merely clouds—came to interrupt the work. Then a second cell is built, with its back to the first and provisioned in the same manner. A third, a fourth, and so on follow, each supplied with honey and an egg and closed before the foundations of the next are laid.

“The flowers which deck the mountain streams with gold supply her with sugary liquid and pollen.”

When all the cells are finished, the Bee builds a thick cover over the group, to protect her grub-babies from damp, heat and cold. This cover is made of the usual mortar, but on this occasion with no small stones in it. The Bee applies it pellet by pellet, trowelful by trowelful, to the depth of about a third of an inch over the cluster of cells, which disappear entirely under the clay covering. When this is done, the nest has the shape of a rough dome, equal in size to half an orange. One would take it for a round lump of mud which had been thrown and half crushed against a stone and had then dried where it was. This outer covering dries as quickly as the cement we use in our houses; and the nest is soon almost as hard as a stone.

Instead of building a brand-new nest on a hitherto unoccupied bowlder, the Mason-bee of the Walls is always glad to make use of old nests built the year before. These need only a little repair to put them in good condition. The Bee who has chosen one of these nests looks about to see what parts need repairing, tears off the strips of cocoon hanging from the walls, removes the fragments of clay that fell from the ceiling when the young Bee of the preceding year bored her way through it, gives a coat of mortar to parts that need it, mends the opening a little, and that is all. She then goes about storing honey and laying her egg, as she would in a new cell. When all the cells, one after the other, are thus furnished, the Bee puts a few touches on the outer dome of cement, if it needs them; and she is through.

From one and the same nest there come out several inhabitants, brothers and sisters, the males with a bright brick-red fleece, and the female of a splendid velvety black, with dark-violet wings. They are all the children of the Bee who built or repaired and furnished the cells. The male Bees lead a careless existence, never work, and do not return to the clay houses except for a brief moment to woo the ladies; they have nothing to do with the housekeeping or the new nests. What they want is the nectar in the flower-cups, not mortar to build with. There are left the sisters, who will be the mothers of the next family. As sisters, they all have equal rights to the nest. They do not go by this rule, however. The nest belongs to the one who first takes possession of it. If any of the others or any neighbors dispute her ownership, she fights them until they have the worst of it and fly away, leaving her in peace.

AN ENEMY OF THE MASON-BEE

All is not smooth sailing after the Mason-bee has finished building her dome of cells. It is then that a certain Stelis-wasp, much smaller than the Mason-bee, appears, looks carefully at the outside of the Mason-bee’s home, and makes up her mind, weak and small as she is, to introduce her eggs into this cement fortress. Everything is most carefully closed: a layer of rough plaster, at least two fifths of an inch thick, entirely covers the cells, which are each of them sealed with a thick mortar plug. The plaster is almost as hard as a rock. Never mind! The little insect is going to reach the honey in those cells.

She pluckily sets to. Atom by atom, she drives a hole in the plaster and scoops out a shaft just large enough to let her through; she reaches the lid of the cell and gnaws it till she catches sight of the honey. It is a slow and painful process, in which the feeble Wasp wears herself out. I find it hard to break the plaster with the point of my knife. How much harder, then, for the insect, with her tiny pincers!

When she reaches the honey, the Stelis-wasp slips through and, on the surface of the provisions, side by side with the Mason-bee’s, she lays a number of her own eggs. The honey-food will be the common property of all the new arrivals, the Stelis-wasp’s grubs as well as the Mason-bee’s.

The next thing for the parasite Wasp to do is to wall up the opening she has made, so that other robbers cannot get in. At the foot of the nest, the Wasp collects a little red earth; she makes it into mortar by wetting it with saliva; and with the pellets thus prepared she fills up the entrance shaft as neatly as if she were a master-mason. The mortar, being red, shows up against the Bee’s house, which is white; so when we see the red speck on the pale background of the Bee’s nest we know a Stelis-wasp has been that way.

As a result of the Stelis’ action, the poor Bee-baby will starve to death. The Wasp’s grubs mature first and eat up all the food.

THE BEE HERSELF TURNED BURGLAR

Sometimes, when a Mason-bee has stayed too long among the flowers, getting honey for her cell, she finds the cell closed when she returns home. A neighbor Bee has taken the opportunity to lay her eggs there, after finishing the building and stocking it with provisions. The real Bee-owner is shut out.

She does not hesitate long about what to do. After she has examined her former home very carefully, to make sure it is closed against her, she seems to say to herself, “An egg for an egg, a cell for a cell. You’ve stolen my house; I’ll steal yours.” She goes to another Bee’s dwelling and patiently gnaws the mortar lid or door. When she has made an opening, she stands bending over the cell, her head half-buried in it, as if thinking. She goes away, she returns undecidedly; at last she makes up her mind. The other Bees, meanwhile, pay no attention to her, not even the one who laid the egg in the cell.

The Bee who has turned burglar snaps up the strange egg from the surface of the honey and flings it on the rubbish-heap as carelessly as if she were ridding the house of a bit of dirt. Then, although there is already plenty of honey in the cell, she adds more from her own stock, lays her own egg, and closes up the house again. The lid is repaired to look like new and everything restored to order. The Bee has had her revenge; her anger is appeased. Next time she lays an egg it will be in her own cell, unless that has again been seized by another.

SOME USEFUL VISITORS OF THE BEES

I have told you about the robber Stelis-wasp who enters the Bee’s cement house and steals the provisions laid up for the Bee-baby; she is not the only one who despoils the poor Mason-bee. There is another Bee, the Dioxys, who acts in about the same way as the Stelis-wasp, except that she sometimes does even worse, and eats up the grub itself, as well as its honey. Then there are the Osmia-bees and the Leaf-cutting Bees, who make themselves very much at home in the Bees’ houses, when they get a chance, keeping out the real owners; and there are also three flies, whose grubs eat the Bee-grub alive! It sometimes seems wonderful that the Mason-bee should ever live to grow up; and you will be glad to hear of three other visitors the Bee-grub has, which actually help instead of making it impossible for it to live. These are three Beetles.

The old nests which the Mason-bees build in, to save themselves the trouble of making new ones, are often in a very insanitary condition. The cells are full of dead larvæ (larva is another word for grub, and both words mean the first stage of the insect after leaving the egg, when it looks like a little worm), which, for some reason or other, could not break through their hard prisons; of honey which has not been eaten and has turned sour; of tattered cocoons, and shreds of skin, left behind when the grubs turned into Bees. All these dead and useless things are, of course, not pleasant to have in any house, especially in a tidy Bee’s.

Here is where the Beetles come to the rescue. They enter the Bee’s house and lay their eggs there. The larvæ, when they come out of the eggs, begin to make themselves useful. Two species of larvæ gnaw the remains of the dead Bees; the third, which is quite a good-looking worm, with a black head and the rest of its body a pretty pink, takes care of the spoiled honey. This worm turns into a Beetle in a red dress with blue ornaments, whom you may often see strolling about the Bee’s house in the working season, tasting here and there drops of honey oozing from some cracked cell. The Bees leave him in peace, as if they knew that it was his duty to keep their house wholesome.

Still later, when the Bee’s house, exposed as it is to wind and weather, cracks and falls to pieces almost entirely, the Bees leave it for good and all, and still other insects take possession of it. These are gypsies, who are not particular where they camp out. Spiders make their homes in the blind alleys which used to be cells, and weave white-satin screens, behind which they lie in wait for passing game. The Hunting-wasps arrange nooks with earthen embankments or clay partitions, and there store up small members of the Spider tribe as food for their families. So we see that the house that the Mason-bee built for herself is useful to many others, good, bad, or indifferent friends of hers as the case may be.