| Chapter I. The Terebinth Aphids. | 7028 |
| Chapter II. Experiments | 6957 |
| Chapter III. Exchanging The Nests | 5405 |
| Chapter IV. More Enquiries Into Mason Bees | 8841 |
| Chapter V. The Story of My Cats | 6758 |
| Chapter VI. The Red Ants | 10148 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8574 |
| Chapter VIII. Parasites | 6362 |
| Chapter IX. The Theory of Parasitism | 7178 |
| Chapter X. The Tribulations of The Mason Bee | 8071 |
| Chapter XI. The Leucopses | 5134 |
