| Chapter I. The Terebinth Aphids. | 4708 |
| Chapter II. Experiments | 4246 |
| Chapter III. Exchanging The Nests | 3124 |
| Chapter IV. More Enquiries Into Mason Bees | 6191 |
| Chapter V. The Story of My Cats | 4450 |
| Chapter VI. The Red Ants | 5967 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6170 |
| Chapter VIII. Parasites | 3966 |
| Chapter IX. The Theory of Parasitism | 4819 |
| Chapter X. The Tribulations of The Mason Bee | 5432 |
| Chapter XI. The Leucopses | 3200 |
