| Chapter I. The Terebinth Aphids. | 7015 |
| Chapter II. Experiments | 6942 |
| Chapter III. Exchanging The Nests | 5395 |
| Chapter IV. More Enquiries Into Mason Bees | 8827 |
| Chapter V. The Story of My Cats | 6747 |
| Chapter VI. The Red Ants | 10127 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8493 |
| Chapter VIII. Parasites | 6341 |
| Chapter IX. The Theory of Parasitism | 7167 |
| Chapter X. The Tribulations of The Mason Bee | 8057 |
| Chapter XI. The Leucopses | 5122 |
