ORGYIA CCNOSA. 79 
most favourable for collecting, and insects simply swarmed: to . 
my great disappoimtment, however, Canosa was not among the 
crowd—only four specimens came to the lamp. In 1875 my 
friend Mr. Richardson took my place at Wicken, working the 
ground with the utmost care, yet he succeeded in taking but 
eight Canosa, and this has been about the average yearly catch 
since then. 
Of the larve I have seen three only, all of which I found 
upon the sedge (Cladiwm Mariscus) which forms the chief 
growth, and indeed the ‘‘ crop” of Wicken Fen. As far as I 
have been able to gather from the sedge-cutters, this seems to be 
its usual food-plant, though probably reed and other herbage 
may enter into the category. 
Before generalizing from these facts, I should like to mention 
similar instances of two other species :— 
Callimorpha dominula used to swarm at Wicken: on May 7th, 
1873, Mr. Fletcher and I collected in a few hours five hundred 
and eighty-two larve, almost all from one patch of dwarf sallow, 
and could have taken hundreds more ‘without stirrmg twenty 
yards—there must have been very many thousands in the square 
mile or so constituting Wicken Fen. The species is still there, 
but in very diminished numbers: the very next season, 
happening to want a few larve, I was quite five hours in 
collecting three dozen. I may mention that a good number of 
these Dominula were turned out at Ranworth Fen, in Norfolk, but 
do not appear to have thriven, for I never saw it there since. 
Leucania phragmitidis was also abundant in 1873: we could 
have taken almost any number feeding on the flower-heads of 
various grasses, and in fact did secure fine series, showing a 
beautiful pink hue—far more. so than Norfolk specimens. In 
1874, however, the species was quite a rarity, and seems ever since 
to have been singularly scarce for so usually common a fen insect. 
All these facts tend to show that, from some cause or other, the 
winter of 1873-4 was especially fatal to some of the Wicken 
insects. According to theory it should have been very wet, with 
heavy floods, but in fact the reverse was the case. In 1872-3, 
Wicken was quite covered, the sallow-bushes alone standing 
above the expanse of floods, yet after this Dominula was so 
abundant, as I have narrated, more so I believe than has been 
the case for some years. The following winter was comparatively 
