| Chapter I. The Terebinth Aphids. | 6197 |
| Chapter II. Experiments | 5860 |
| Chapter III. Exchanging The Nests | 4429 |
| Chapter IV. More Enquiries Into Mason Bees | 7744 |
| Chapter V. The Story of My Cats | 5934 |
| Chapter VI. The Red Ants | 8717 |
| Chapter VII. Some Reflections Upon Insect Psychology | 7554 |
| Chapter VIII. Parasites | 5484 |
| Chapter IX. The Theory of Parasitism | 6360 |
| Chapter X. The Tribulations of The Mason Bee | 7107 |
| Chapter XI. The Leucopses | 4399 |
