6 
We find that the surface caterpillars, which w 7 e have 
seen feeding at the roots of Turnips, Beet, or other 
crops during the summer, do not lie about haphazard 
during the winter, but before the time comes for their 
torpid state (or for the change to the chrysalid stage, in 
which some pass the winter season) they form for them¬ 
selves cells or hollow oval chambers, more or less 
smoothed on the inner surface, a little below ground. 
The caterpillar of the common Heart and Dart Moth 
(.Noctua (. Agrotis ) exclamationis) , which will feed almost 
on any field or garden crop, turns to chrysalis during 
September or October in an earth-cell three or four 
inches below the surface ; the Cabbage Moth ( Mcimestra 
Brassicce ) caterpillar also for the most part goes into 
chrysalis similarly beneath the surface; the Turnip 
Moth (Noctua ( Agrotis ) segetum) lives in caterpillar-state 
below the surface, either feeding out of reach of hard 
frost or coiled up in a cell formed for itself in a ball of 
earth ; and the caterpillar of the Great Yellow Under¬ 
wing Moth (Tryphcena pronuba) , which feeds sometimes 
on Turnips, and is stated also to be destructive to grass 
roots, although, like the Turnip-grub, it feeds (w T eatlier 
permitting) during winter, yet secures itself from over¬ 
exposure, and when it goes into chrysalis, in the spring, 
it is in an earth-cell. 
Now in these earth-cells, in which many kinds of 
larvcc (caterpillars, grubs, or whatever we may like to call 
them) pass the winter, they are protected from drying 
winds and from sudden changes of temperature; the 
smoothed inner surface keeps an unchanged atmosphere 
round them, and also appears to exclude wet, so that 
the caterpillar lies clean and dry within, without risk of 
its breathing-pores being choked by mud, which, 
though not possibly of importance to it whilst torpid, is 
a very serious matter when it wakes from its winter 
sleep. 
Both caterpillars and chrysalids vary in the amount 
of cold they can endure. The caterpillar of the Yellow 
Underwing Moth will bear being frozen into a ball of ice 
