| Chapter I. The Terebinth Aphids. | 6914 |
| Chapter II. Experiments | 6803 |
| Chapter III. Exchanging The Nests | 5257 |
| Chapter IV. More Enquiries Into Mason Bees | 8697 |
| Chapter V. The Story of My Cats | 6638 |
| Chapter VI. The Red Ants | 9987 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8362 |
| Chapter VIII. Parasites | 6216 |
| Chapter IX. The Theory of Parasitism | 7059 |
| Chapter X. The Tribulations of The Mason Bee | 7941 |
| Chapter XI. The Leucopses | 5022 |
