THE ANTHRAX FLY 



to time, I could see one passing far away, with an im- 

 petuous rush. I would lose her in the distance ; and that 

 was all. It was impossible to be present at the laying 

 of the egg. In vain I enlisted the services of the small 

 boys who keep the sheep in our meadows, and talked 

 to them of a big black Fly and the nests on which 

 she ought to settle. By the end of August my last 

 illusions were dispelled. Not one of us had succeeded 

 in seeing the big black Fly perching on the dome of 

 the Mason-bee. 



The reason is, I believe, that she never perches there. 

 She comes and goes in every direction across the stony 

 plain. Her practised eye can detect, as she flies, the 

 earthen dome which she is seeking, and having found it 

 she swoops down, leaves her egg on it, and makes off 

 without setting foot on the ground. Should she take a 

 rest it will be elsewhere, on the soil, on a stone, on 

 a tuft of lavender or thyme. It is no wonder that 

 neither I nor my young shepherds could find her egg. 

 Meanwhile I searched the Mason-bees' nests for grubs 

 just out of the egg. My shepherds procured me heaps 

 of the nests, enough to fill baskets and baskets; and 

 these I inspected at leisure on my work-table. I took 

 the cocoons from the cells, and examined them within 

 and without: my lens explored their innermost recesses, 

 the sleeping larva, and the walls. Nothing, nothing, 

 nothing ! For a fortnight and more nests were searched 



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