| Chapter I. The Terebinth Aphids. | 6729 |
| Chapter II. Experiments | 6550 |
| Chapter III. Exchanging The Nests | 4919 |
| Chapter IV. More Enquiries Into Mason Bees | 8340 |
| Chapter V. The Story of My Cats | 6459 |
| Chapter VI. The Red Ants | 9713 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8144 |
| Chapter VIII. Parasites | 6028 |
| Chapter IX. The Theory of Parasitism | 6902 |
| Chapter X. The Tribulations of The Mason Bee | 7736 |
| Chapter XI. The Leucopses | 4867 |
