| Chapter I. The Terebinth Aphids. | 7140 |
| Chapter II. Experiments | 7101 |
| Chapter III. Exchanging The Nests | 5546 |
| Chapter IV. More Enquiries Into Mason Bees | 8998 |
| Chapter V. The Story of My Cats | 6846 |
| Chapter VI. The Red Ants | 10567 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8656 |
| Chapter VIII. Parasites | 6524 |
| Chapter IX. The Theory of Parasitism | 7267 |
| Chapter X. The Tribulations of The Mason Bee | 8180 |
| Chapter XI. The Leucopses | 5203 |
