| Chapter III. The Distribution of Sexes | 636 |
| Chapter XII. The Halicti: a Parasite | 714 |
| Chapter VIII. Parasites | 605 |
| Chapter IX. The Theory of Parasitism | 642 |
| Chapter X. The Tribulations of The Mason Bee | 921 |
| Chapter III. Another Prober (Perforator) | 775 |
| Chapter XVI. A Parasite of The Maggot | 934 |
