114 THE ENTOMOLOGIST’S RECORD. 
cannot contradict the statement, though I cannot believe it. The 
larva has been, I read, twice publicly exhibited in London, resting 
upon A. millefolium, but I fancy this has been from motives of policy 
rather than as a demonstration of fact. I have tried common 
mugwort (Artemisia vulgaris) without success, ‘‘ southernwood”’ is the 
well known substitute for A. maritima, and I have found that both 
these plants will be deserted for the common wormwood (A. absinthium). 
In fact, I find that the latter plant produces finer imagines than the 
better known pabula, and it was upon this that I last year reared from 
the egg a partial second brood, out of doors, and entirely unconfined. 
The clothing of the larva (pl. vii., fig. 5) is one of the most remarkable 
points in the life-history of the species. One cannot but wonder what is the 
purpose or use of this fragmentary case, so unusual amongst lepidoptera, 
that I can recall only one similar, that constructed by the larva of the 
nearly related P. pustulata ; but the food-plant, habits, and habitats of 
these two insects are so completely opposite, that one fails to see what 
needs, except of concealment, they can have in common. As a matter 
of fact the use is more clear in the case of the species before us than 
in that of its relation, as we can understand that P. smaragdaria 
requires some sort of protection from the floods, to which its particular 
habitat is periodically subjected. The saltings upon which the food- 
plant flourishes are below the high water mark of flood-tides, and, 
therefore, at such times, the plants and the larvee feeding thereon, are 
for a time (probably never more than an hour) totally submerged. 
Mr. Auld in his paper (Hint. Mo. Mag., March, 1895, p. 57) mentions 
this fact, and Mr. Whittle and I, one day, when the larve were very 
abundant, and our boxes full, watched for some time the rising water 
gradually, but completely, covering the larve. The bath troubled them 
not in the least; thrown upon the water, the case acted like a life-buoy, 
and the larve which were upon the plants did not let go, they calmly 
and resignedly held on. Here certainly comes in one of the uses of 
the case. The fragments of leaf and the entwined silk imprison a 
large quantity of air, and this is quite sufficient—probably much more 
than sufficient—for the period of submergence. These baths must be 
rather trying during the winter months of hybernation, and the coat will 
then not only keep its wearer dry, but warm as well, as he sleeps low 
down amongst the roots and grass. So difficult is it to remove this 
imprisoned air, that, for the purpose of mounting for the microscope, I 
have found it necessary to put the larve into ether before placing in 
the cells. Everybody seems to think that the fragments constituting 
the coats are gummed, or stuck on to its back by the larva, by means of 
some kind of marine glue or hydraulic cement. I could never believe 
that, but could not say how it was effected until Mr. Bacot put me on 
the scent, and the whole credit of the observation belongs to him. The 
secret will be revealed by the drawing which I have made. There are 
(from the time of hatching) special knobs or hooks upon the skin of 
the larva, to which, by means of silken threads, it can fasten the bits 
where they are most wanted. There is a strange variation in these special 
hairs or knobs, in that they are not of the same character throughout the 
whole period of larval life. When the larva first comes from the egg, 
hairs, with either ‘“ turf-cutter’’ heads, or ‘trumpet ” heads (pl. vii., 
figs. 3a-d), enable the young caterpillar easily to entangle its delicate silk, 
and the minute fragments of plant-hair, dust, &c., in the form of little 
