40 ORDER COLEOPTERA. 



the cause. In looking more closely into these matters, one might be assured, that in most 

 eases, an enemy of the insect which has disappeared, has produced the happy result. I can 

 furnish some proofs in support of this opinion. 



■ •• The thick foliage of a fine avenue of poplars was all at once attacked by an immense 

 quantity of the caterpillars of Boinbyx dispar. I thought of giving them the Calosoma 

 sycophanta for company; as, like them, it passes its life upon the trees, feeding upon the 

 caterpillars which it meets, and even deposits its eggs in their nest, that its voracious 

 progeny may procure nourishment more easily and in greater abundance. Well ! this insect 

 multiplied itself with a rapidity truly astonishing ; and the oaterpillars disappeared, with- 

 out those who were witnesses to the destruction having the hast idea of the causes which 

 produced it." The author then gives it as his opinion that the neighborhood of the city of 

 Toulouse is so little ravaged by the Melolontha vulgaris, which is so destructive in other 

 parts of France, because the Carabus auratus is very common in the fields, meadows and 

 gardens. It is known, he remarks, that the Carabus auratus Beizes and devours the Melo- 

 lontha previous to the deposition of its eggs ; and that it is more fond of these, than of any 

 part of the insect. 



• '-One would be much deceived," he continues, " in believing that it is always easy to 

 make an advantageous use of this means of destruction, a profound study of the manners of 

 insects l>eing often indispensable to arrive at the end proposed." Here is an example : "The 

 most robust of our carabi, the Procrustes coriaceus (Linnkis), had served me admirably in 

 the centre of France to destroy the little insects which attack the plants in gardens : here 

 (in the south) this insect does not destroy the same species; and although very common, it 

 is. unknown, or hardly every met with. The reason is, that in the centre, the west, and 

 probably the north of Fiance, this procrustes is diurnal, requiring only cool and shady 

 places : with us (in the south, under a warmer climate) it is, on the contrary, essentially 

 nocturnal, and therefore destroys only such insects as are, like itself, nocturnal, or which 

 remain within its reach during the obscurity of night." 



' " In transporting into my garden twenty of the Carabus auratus, I had thought to 

 destroy the collections of Forficula (no destructive species found in America) which had 

 chosen it for the theatre of their ravages." To his great astonishment, the carabi, which 

 will actually destroy the forficute, wire either found starved to death, or left the place; 

 and the latter continued their devastations! The reason given is, that the forficula are 

 • itially nocturnal, and. during the day, keep themselves hidden in crevices into which 

 the carabi cannot follow them : these latter, too, are only active during the middle of the 

 day, and in the heat of the sun. But the resources of our persevering entomologist were 

 not yet exhausted; his next expedient being to introduce a smaller carnivorous insect 

 common in Prance, the Staphylinus o/ens, which, he remarks, "filled all the necessary 

 conditions for the destruction of the forficula." 



