Lesson C

The Leaf-cutter Bee

Leading thought—When we see the edges of rose leaves with holes of regular pattern in them, some of the holes being oblong and some circular, we know the leaf-cutter bee has cut them to make her cradle cups.

Method—It is very easy to find in June or autumn the leaves from which the leaf-cutter bee has cut the bedding for her young. Encourage the pupils to look for the nest during the summer and to bring some of the cups to school when they return, where they may be studied in detail; meanwhile the teacher may tell the story of the nest. This is rather difficult for the pupils to work out.

Observations—1. Do you find rose leaves with round holes cut in their edges? Do you find on the same bush some leaflets with oblong holes in them? Sketch or describe the rose leaf thus cut, noting exactly the shape of the holes. Are the circular holes of the same size? Are the long holes about equal in size and shape? Do you find any other plants with holes like these cut in them? Do you find any petals of flowers thus cut?

2. What do you think made these holes? If an insect was taking a leaf for food would the holes be as regular? Watch the rose bush carefully and see if you can discover the insect which cuts the leaf.

3. Have you ever seen the little black bee carrying pieces of rose leaves between her front feet? With what instrument do you suppose she cut the leaves? Where do you think she was going?

4. Have you ever found the nest of the leaf-cutter bee? Was it in a tunnel made in dead wood or in some crack or cranny? How many of the little rose leaf cups are there in it? How are the cups placed? Are the little bees still in the cups or can you see the holes through which they crawled out?

5. Take one cup and study it carefully. How are the pieces of leaves folded to make the cups? How is the lid put on? Soak the cup in water until it comes apart easily. Describe how many of the long pieces were used and how they were bent to make a cup. Of how many thicknesses is the cover made? Are the covers just the same size or a little larger than the top of the cup? How does the cover fit so tightly?

6. If you find the nest in July or early August, examine one of the cups carefully and see what there is in it. Take off the cover without injuring it. What is at the bottom of the nest? Is there an insect within it? How does it look? What is it doing? Of what do you think its food was made? How and by whom was the food placed in the cup? Place the nest in a box or jar with mosquito netting over the top, and put it out of doors in a safe and shaded place. Look at it often and see what this insect changes into.

7. If the mother bee made each little nest cup and put in the bee-bread, and honey for her young, which cup contains the oldest of the family? Which the youngest? How do you think the full-grown bees get out of the cup?

8. Do you think that the same species of bee always cuts the same sized holes in a leaf? Is it the same species which cuts the rose leaves and the pansy petals?