| Chapter III. The Distribution of Sexes | 3988 |
| Chapter XII. The Halicti: a Parasite | 4465 |
| Chapter VIII. Parasites | 4416 |
| Chapter IX. The Theory of Parasitism | 5472 |
| Chapter X. The Tribulations of The Mason Bee | 5932 |
| Chapter III. Another Prober (Perforator) | 5161 |
| Chapter XVI. A Parasite of The Maggot | 5604 |
