| Chapter I. The Terebinth Aphids. | 5098 |
| Chapter II. Experiments | 4642 |
| Chapter III. Exchanging The Nests | 3454 |
| Chapter IV. More Enquiries Into Mason Bees | 6606 |
| Chapter V. The Story of My Cats | 4826 |
| Chapter VI. The Red Ants | 6515 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6487 |
| Chapter VIII. Parasites | 4354 |
| Chapter IX. The Theory of Parasitism | 5397 |
| Chapter X. The Tribulations of The Mason Bee | 5834 |
| Chapter XI. The Leucopses | 3576 |
