| Chapter I. The Terebinth Aphids. | 4676 |
| Chapter II. Experiments | 4203 |
| Chapter III. Exchanging The Nests | 3091 |
| Chapter IV. More Enquiries Into Mason Bees | 6152 |
| Chapter V. The Story of My Cats | 4413 |
| Chapter VI. The Red Ants | 5910 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6143 |
| Chapter VIII. Parasites | 3937 |
| Chapter IX. The Theory of Parasitism | 4778 |
| Chapter X. The Tribulations of The Mason Bee | 5397 |
| Chapter XI. The Leucopses | 3176 |
