| Chapter III. The Distribution of Sexes | 4994 |
| Chapter XII. The Halicti: a Parasite | 5378 |
| Chapter VIII. Parasites | 5407 |
| Chapter IX. The Theory of Parasitism | 6275 |
| Chapter X. The Tribulations of The Mason Bee | 6993 |
| Chapter III. Another Prober (Perforator) | 6004 |
| Chapter XVI. A Parasite of The Maggot | 6452 |
