222 DISEASES OF INSECTS. 



glass, after some days he examined it again ; when he 

 observed that it had spun the outline of a vertical web, 

 had stretched threads from the top to the bottom of the 

 glass and from one side to the other, and had also spun 

 the radii that meet in the centre, and this was all ; but 

 what was remarkable, the larva that had fed upon it was 

 suspended in the centre of this web, where it was en- 

 gaged in spinning its own cocoon, while the spider, ex- 

 hausted by this last effort, had fallen dead to the bottom 

 of the glass. It cannot be asserted positively that this 

 suspension of the larva of the Ichneumon in the centre 

 of the web always takes place ; but if it does, as seems 

 most probable, it shows that this little parasite is en- 

 dowed with an instinct which causes it so to act upon 

 the spider as may induce it to spin a web so nicely timed 

 as to be sufficiently complete at the period of its death 

 and of the change of the Ichneumon, for the latter to 

 cast it down and assume its station a . 



But the great bulk of the parasitic Hymenopterous de- 

 vourers of larvae have their assigned station within the 

 body. As Entomologists in breeding insects have paid 

 their principal attention to Lepidoptera^ it necessarily 

 follows that their Ichneumon infesters must be most 

 generally known ; but doubtless the larvae of the other 

 Orders are not wholly liberated from this scourge: they 

 also require to be kept within due limits, and have their 

 appropriate parasites. Some, however, in most of them 

 have been detected : of which I shall now proceed to 

 state to you the most interesting examples, beginning 

 with the Coleoptera. 

 AlysiaManducator*) remarkable for having mandibulas 



a De Geer ii. 863. b Panzer Fn. Germ. Intl. Ixxii. 4. 



