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 viihjaris) 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. absintJiiiuii). 

 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 (pi. 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. pustiilata ; 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 larvae feeding thereon, are 

 for a time (probably never more than an hour) totally submerged. 

 Mr. Auld in his paper {Ent. Mo. Mag., March, 1895, p. 57) mentions 

 this fact, and Mr. Whittle and I, one day, when the larvfe were very 

 abundant, and our boxes full, watched for some time the rising water 

 gradually, but completely, covering the larvfe. The bath troubled them 

 not in the least ; thrown upon the water, the case acted like a life-buoy, 

 and the larvfe 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 larvae 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 hoAV it was efl'ected 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 Qgg, 

 hairs, with either "turf-cutter" heads, or "trumpet "heads (pi. vii., 

 figs. 3rt-(/), enable the young caterpillar easily to entangle its delicate silk, 

 and the minute fragments of plant-hair, dust, &c., in the form of little 



