





| 129 THE INSECT WORLD. 
\ found in Paris, in the garden of the ficole de Pharmacie. It had 
| become common in 1822 in the departments of the Seine, the 
f Somme, and the Aisne. In 1827, its presence in Belgium was 
| announced. 
The apple-tree aphis, according to M. Blot, can only exist on 
| that tree. Carried away and placed on any other, it very soon 
. | perishes. It does not attack the blossom, the fruit, nor the | 
leaves, but fixes itself on the lower part of the trunk, whence it 
i propagates itself downwards as far as the roots, underneath the 
eraftings, &e. It also likes to lodge in cracks of the trunk and | 
large branches. But it always looks out for a southern, and 
avoids a northern aspect. It is not active, walks very little, and | 
sts dissemination from one place to another can only be explained 
by the facility with which so small an insect can be transported | 
by the wind, its lightness being still more increased by the down 






































which covers it. 
The Myzoaylus mali renders the wood knotty, dry, hard, brittle, | 
y and brings on rapidly all the symptoms which characterise old | 
age and decay in attacked trees. M. Blot recommends the fol- 
| lowing means for preserving the apple-trees from this insect: 
Employ for the seed beds the pips of bitter apples only ; cive to 
the nursery and to the plants only as much shelter as is absolutely | 
necessary ; avoid those sites which are too low and too damp; 
. encourage the circulation of air, and the desiccation of the soil ; 
surround the foot of each apple-tree with a mixture of soot or of 
tobacco and fine sand. | 
As for the manner of freeing a tree once invaded by this insect, | 
the most simple plan is to rub the trunk and the branches, in 
order to crush the insects, or to employ a brush or broom. 
We spoke above of the reproduction of the aphis, but without 
entering into any particular details: we will now touch upon this 
question, one of the most interesting in natural history. 
It was at the time when Réaumur was writing his immortal 
“ Tistoire des Insectes,” when Tremblay was publishing his ad- 
mirable researches on the freshwater Hydra, whose prodigious 
vitality we have mentioned in our work on Zoophytes and 
Molluses,* that another naturalist astonished the learned world 
* «The Ocean World.” London: Chapman and Hall, 1868.—Ep. 

