STATES OF INSECTS. 65 



that of the parent fly — from their slight motion when 

 first extruded — from spiraculiform points which run down 

 each side of them — and lastly, from their producing not 

 a larva, as all other insects' eggs do, but perfect flies in 

 the winged state — inferred, and doubtless with reason, 

 that they are not real eggs, but pupae, or larva? just ready 

 to assume the pupa state, which, however strange it may 

 seem, have passed the egg and larva states in the body 

 of the mother 3 . 



Insects, therefore, as to their mode of birth, may be 

 divided into — 



I. Ovo-viviparous, subdivided into — 



1 . Larviparous, coming forth from the matrix of the 



mother in the state of larvae, as the Scorpion 

 (Scorpio), the Flesh-fly (Musca), the Plant-louse 

 (Aphis), &c. 



2. Pupiparous, continuing in the matrix of the mo- 



ther during the larva state, and coming forth in 

 that of pupa, as the Forest-fly (Hippobosca 

 equina), the Sheep-louse (Melophagus ovinus), 

 the Bat-louse (Nycteribia Vespertilionis), &c. 



II. Oviparous. All other insects. 



Our business for the remainder of this letter will be 

 with the latter description of these little animals. 

 - The unerring foresight with which the female deposits 

 her eggs in the precise place where the larvae, when ex- 

 cluded, are sure to find suitable food ; and the singular 

 instruments with which, for this purpose, the extremity 

 of their abdomen is furnished, have been noticed in a 

 former letter b , and those last mentioned will be adverted 

 to in a future one. I shall now, therefore, confine myself 



a Reaum. vi. Mem. xiv. De Geer, vi. 280. 

 b See Vol. I. Lett. xi. 

 VOL. III. F 



