168 ANIMAL PARASITES AND MESSMATES. 



There are around us, even in the midst of our cities, 

 insects known under the name of Scolyti, which at- 

 tracted much attention a few years ago. The trees by the 

 side of the high roads, and even those of our boulevards, 

 were attacked by them, and it was feared for a time that 

 it would not be possible to arrest this new plague, which 

 appeared simultaneously with the oidium of the vine 

 and the parasite of the potato. 



The boulevards of Brussels were planted with fine 

 elms, and these trees were disappearing one after 

 another. The seeds of this plague were also sown in 

 France, in the environs of Paris. Mons. Eug. Eobert 

 had paid attention to it, and had announced to the 

 Academie des Sciences a remedy to arrest the evil. 



The regency of Brussels invited Mons. Eug. Eobert 

 to come and put in practice the means which he had 

 recommended to destroy the scolyti ; but, if I remember 

 rightly, the death of the trees quickly followed that of the 

 scolyti. Nature, instead of employing pitch to arrest 

 this plague, has simpler and more expeditious means; 

 these are, to bring forward an insect equally small, 

 which multiplies sufficiently to keep the terrible Scolytus 

 under. Such is the part which has devoted on the 

 Bracon iniator. It simply lays its eggs in the bodies of 

 the larvae of the scolyti, and destroys them. 



Wesmael has related a curious fact of this kind, 

 concerning this eneray of our plantations. These little 

 people can be well trusted to manage their own affairs. 

 Each of these hymenoptera ascertains with an admirable 

 instinct the place where the larvae of the scolyti are to 

 be found, and with its long flexible ovipositor darts an 

 egg into the body of its victim. 



