AN INVADEE 205 



What a fury of destruction once the ravager is 

 installed in the vegetable treasure-house I My bottles 

 give abundant evidence of this. One single haricot bean 

 shelters a numerous family; often as many as twenty 

 members. And not one generation only exploits the 

 bean, but three or four in the year. So long as the skin 

 of the bean contains any edible matter, so long do new 

 consumers establish themselves within it, so that the haricot 

 finally becomes a mere shell stuffed with excreta. The 

 skin, despised by the grubs, is a mere sac, pierced with 

 holes as many as the inhabitants that have deserted it ; 

 the ruin is complete. 



The Bruchus pisi, a solitary hermit, consumes only so 

 much of the pea as will leave a cell for the nymph ; the 

 rest remains intact, so that the pea may be sown, or it will 

 even serve as food, if we can overcome our repugnance. 

 The American insect knows nothing of these limitations ; 

 it empties the haricot completely and leaves a skinful of 

 filth that I have seen the pigs refuse. America is anything 

 but considerate when she sends us her entomological 

 pests. We owe the Phylloxera to America ; the Phyl- 

 loxera, that calamitous insect against which our vine- 

 growers wage incessant war : and to-day she is sending us 

 the haricot-weevil, which threatens to be a plague of the 

 future. A few experiments gave me some idea of the 

 peril of such an invasion. 



For nearly three years there have stood, on my labora- 

 tory table, some dozens of jars and bottles covered with 

 pieces of gauze which prevent escape while permitting of 

 a constant ventilation. These are the cages of my 

 menagerie. In them I rear the haricot-weevil, varying 

 the system of education at will. Amongst other things I 



