| Chapter I. The Terebinth Aphids. | 5686 |
| Chapter II. Experiments | 5329 |
| Chapter III. Exchanging The Nests | 3985 |
| Chapter IV. More Enquiries Into Mason Bees | 7250 |
| Chapter V. The Story of My Cats | 5436 |
| Chapter VI. The Red Ants | 7759 |
| Chapter VII. Some Reflections Upon Insect Psychology | 7089 |
| Chapter VIII. Parasites | 5013 |
| Chapter IX. The Theory of Parasitism | 5897 |
| Chapter X. The Tribulations of The Mason Bee | 6524 |
| Chapter XI. The Leucopses | 4040 |
