| Chapter I. The Terebinth Aphids. | 6888 |
| Chapter II. Experiments | 6754 |
| Chapter III. Exchanging The Nests | 5192 |
| Chapter IV. More Enquiries Into Mason Bees | 8643 |
| Chapter V. The Story of My Cats | 6607 |
| Chapter VI. The Red Ants | 9939 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8313 |
| Chapter VIII. Parasites | 6185 |
| Chapter IX. The Theory of Parasitism | 7039 |
| Chapter X. The Tribulations of The Mason Bee | 7910 |
| Chapter XI. The Leucopses | 5001 |
