| Chapter I. The Terebinth Aphids. | 7015 |
| Chapter II. Experiments | 6943 |
| Chapter III. Exchanging The Nests | 5395 |
| Chapter IV. More Enquiries Into Mason Bees | 8828 |
| Chapter V. The Story of My Cats | 6747 |
| Chapter VI. The Red Ants | 10130 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8496 |
| Chapter VIII. Parasites | 6342 |
| Chapter IX. The Theory of Parasitism | 7168 |
| Chapter X. The Tribulations of The Mason Bee | 8060 |
| Chapter XI. The Leucopses | 5123 |
