118 
Observations on the various Insects 
which the corn and lime may be sown together in calm weather. 
Scattering ashes immediately before and after sowing the seed, or 
when the plants begin to shoot up, might prevent these caterpillars 
from attacking a crop or drive them away. Tlie same Society 
states, on the authority of many farmers, that corn has been 
effectually protected from seed-eating caterpillars by sticking in- 
verted young fir-trees, having the tops first cut off, into various 
parts of the field I If this be correct, we are at a loss for an ex- 
planation of the phenomenon ; yet it is maintained, so certain is the 
effect, that if the caterpillars had already infested a field it would 
cause them to vanish. 
Kollar is of opinion that the advantages derived from sowing 
hemp round the borders of a field do not arise from any disagree- 
able scent being imparted, but from its attracting small birds, 
which resort to it for its seed and for shelter, and, by feeding upon 
the hurtful insects around them, they greatly diminish their 
numbers. It is difficult to account for the absence of the Surface- 
caterpillars from our field-crops for many years together, unless, 
as is generally the case, they are occasionally overpowered by 
parasitic insects ; it is thei'efore not a little remarkable that I have 
never met with any of the parasites which we may presume are 
attached to these caterpillars ; it is true that, as far as regards the 
Noctua Brassiccs, I find in gardens in June and July great 
numbers of an Ichneumon called Exetastes oscillator ins of 
Fabricius,* which appears to accompany that species, but, never 
having bred it, I have no direct evidence of their being connected 
in their economy. 
I shall conclude the history of the Surface-caterpillars by giving 
directions for the rearing them, trusting that it may lead us to a 
better knowledge of some parts of their history. When we take 
any caterpillar or other larva of an insect from the field or garden, 
the nearer we can approach to keeping it in its natural state, the 
better chance we shall have of rearing the perfect insect, whether 
moth, fly, or otherwise : the first object is therefore to plant the 
food it requires in the right soil; but if the larva feed upon the 
leaves or flowers of a tree or plant, a twig may be cut off and 
placed in a vial or small bottle of water in the cage : the next thing 
is to keep the earth enclosed sufficiently damp but not too wet, 
and this is most difficult. The best mode undoubtedly is to take 
a butter-firkin or small useless box, and bore the head or bottom 
full of holes, which are necessary to drain it, but not large enough 
to allow the animals to get through ; then sink the barrel in a 
shady yet airy spot in the garden, within 6 or 8 inches of the 
surface : this being done, fill it with the proper soil to the same 
* Curtis s Guide, Gen. 524, No. 15. 
