HIS little cement worker is a nervous and fidgety creature, jerking her wings constantly as she walks around in the sunshine; but perhaps this is not nervousness, but rather to show off the rainbow iridescence of her black wings; surely such a slim-waisted being as she, has a right to be vain. No tight lacing ever brought about such a long, slim waist as hers; it is a mere pedicel and the abdomen is a mere knob at the end of it. The latter seen from the outside, would seem of little use as an abdomen; but if we watch the insect flying, we can see plainly that it is used to steer with.
In early summer, we find this black wasp at her trade as a mason. She seeks the edges of pools or puddles where she works industriously, leaving many little holes whence she takes mud to mix with the saliva, which she secretes from her mouth to make firm her cement. This cement she plasters on the under side of some roof or rafter or other protected place, going back and forth until she has built a suitable foundation. She works methodically, making a tube about an inch long, smooth inside but rough outside, the walls about one-eighth of an inch thick. She does all of the plastering with her jaws, which she uses as a trowel. When the tube is completed except that the end is left open, she starts off in quest of spiders, and very earnestly does she seek them. I have seen her hunt every nook and corner of a piazza for this prey. When she finds a spider, she pounces upon it and stings it until it is helpless, and carries it to her cement tube, which is indeed a spider sarcophagus, and thrusts it within. She brings more spiders until her tube is nearly full; she then lays an egg within it and then makes more cement and neatly closes the door of the tube. She then places another tube by the side of this, which she provisions and closes in the same way; and then she may make another and another tube, often a half dozen, under one adobe roof.
The wasp in some mysterious way knows how to thrust her sting into the spider's nervous system in a peculiar way, which renders her victim unable to move although it yet lives. The wasp is no vegetarian like the bee, and she must supply her young with wasp-meat instead of bee-bread. Since it is during the summer and hot weather when the young wasps are hatched and begin their growth, their meat must be kept fresh for a period of two or three weeks. So these paralyzed spiders do not die, although they are helpless. It is certainly a practical joke with justice in it, that these ferocious creatures lie helpless while being eaten by a fat little grub which they would gladly devour, if they could move.
The wasp larva is a whitish, plump grub and it eats industriously until the spider meat is exhausted. It then weaves a cocoon of silk about itself which just covers the walls of its home tube, like a silken tapestry; within this cocoon the grub changes to a pupa. When it finally emerges, it is a full-grown wasp with jaws which are able to cut a door in the end of its tube, through which it comes out into the world, a free and accepted mason. The females or queens, which issue late in the season, hide in warm or protected places during the winter; they particularly like the folds of lace window curtains for hibernating quarters. There they remain until spring comes, when they go off to build their plaster houses.
There are about seventy species of mud wasps in our country. Some provision their nests with caterpillars instead of spiders. This is true of the jug-builder, which makes her nest jug-shaped and places two or three of them side by side upon a twig. She uses hair in her mortar, which makes it stronger. This is necessary, since the jug is saddled upon twigs and is more exposed to the rain than is the nest of the most common mud-dauber. The jug-builder is brown in color and has yellow markings on the abdomen; but she does not resemble the yellow-jackets, because she has a threadlike waist. There are other species of mud wasps which use any small cavity they can find for the nest, plastering up the opening after the nest has been provisioned and the egg laid. We often find keyholes, knot-holes and even the cavity in the telephone receiver, plastered up by these small opportunists.
The mud-dauber which is the most common, and most likely to be selected for this lesson, is a slender creature and looks as if she were made of black tinsel; her body gives off glints of steel and blue; her abdomen constantly vibrates with the movement of breathing. Her eyes are large and like black beads; her black antennæ curve gracefully outward, and her wings, corrugated with veins, shimmer with a smoky blue, green and purple. She stands on her black tip-toes when she walks, and she has a way of turning around constantly as if she expected an attack from the rear. Her wings, like those of other mud-wasps, are not folded fan-wise like those of the yellow-jacket, but are folded by each other over her back.
Leading thought—There are certain wasps which gather mud and mix it into mortar with which to build nests for their young. Within these nests, the mother wasp places spiders or insects which are disabled by her sting, for the food of the young wasps.
Method—Have the pupils bring the homes of the mud wasps to school for observation. The wasps themselves are very common in June and also in September, and they also may be studied at school and may be passed around in vials for closer observation; they do not sting severely when handled, the sting being a mere prick. The purpose of the lesson should be to stimulate the pupils to watch the mud-daubers while building their nests and capturing their prey.
1. Where did you find the mud-dauber's nest? How was it protected from the rain? Was it easily removed? Could you remove it all, or did some of it remain stuck fast?
2. What is the shape of the nest? How does it look inside? Of how many tubes does it consist? How long is each tube? Were the tubes laid side by side?
3. Of what material was the nest made? Is it not much harder than mud? How did the wasp change the mud to cement? Where did she get the mud? How did she carry it? With what tools did she plaster it?
4. For what purpose was the nest made? Is the inside of the tubes smooth as compared with the outside of the nest?
5. Write a little story about all that happens in one of these tubes, including the following points: What did the mother wasp place in the tube? How and why did she close it? What hatched from the egg she placed within it? How does the young wasp look? On what does it feed? What sort of a cocoon does it spin? How does it get out of the nest when full-grown?
6. Describe the mud-dauber wasp. How large is she? What is the color of her body? Of her wings? How many wings has she? How are her wings folded differently from those of the yellow-jacket? Describe her eyes; her antennæ; her legs; her waist; her abdomen.
7. Where did you find the wasp? How did she act? Do you think that she can sting? How does she pass the winter?
8. Do you know the mud wasps which build the little, jug-shaped nests for their young? Do you know the mud wasps which utilize crevices and keyholes for their nests and plaster up the opening?
9. Do you know about the digger wasps which pack away grasshoppers or caterpillars in a hole in the ground, in which they lay their egg and then cover it?
Supplementary reading—Insect Stories, Kellogg; Wasps, Social and Solitary, Peckham; Wasps and their Ways, Morley; The Ways of the Six-footed, Comstock; Home Studies in Nature, Treat.