177 
when nearly full grown, we find numbers of living 
young in them, which no doubt must be vivip- 
arously established on the plants for it is clear 
the emago only quits the ova. 
The existence of those voracious animals is 
soon exhibited by the leaves being lacerated. 
Sometimes they will be found on the underside, 
and at other times on the upper surface of the leaf, 
and they generally prove more destructive to this 
tribe of plants than the former. Both those 
Caterpillars sometimes prevail to a considerable 
degree of injury to the Brassica tribe, which proved 
to be the case in 1825. It will remembered 
tliat it was not uncommon to see whole crops of 
the Brassica tribe conq^letely dissected, leaving- 
only the stronger ribs of the leaf, with its stem, 
to remunerate the proprietor for his labour. 
For their Destruction. — I know no 
better plan for their eradication than gathering- 
them by hand : a boy or woman would go over a 
great number of plants in one day. It should be 
observed to take them in time before much injury 
is done to the plant, and to examine in the per- 
formance the under as well as the upper surface of 
the leaf. The Mixture (No. 6 or 1 ) will com- 
pletely destroy them done on with a wisk or 
engine, but as the other is so readily done that I 
should prefer its being adopted. 
Another Caterpillar also attacks tliis genus of 
plants. It is thicker than the preceding ones 
mentioned ; about two inches long, of a sooty 
