LOCALITIES FOR BEGINNERS. 171 
at that time very rare; and, flying over the oats just over 
the fence, he also took the then new Cosmopteryx Lienigiella. 
In the same field he also took the very rare Argyrolepia Schreiber- 
siana, and, for the first time, discovered Hupithecia viminata, then 
supposed to feed upon osiers (Salix viminalis}, but now known to 
feed on the flowers of the Valerian. Passing these ash trees we 
come to a gate leading on to a wide bank; following this we arrive 
at a small pumping-engine, and opposite this we may cross the 
ditch into the fen proper. 
On entering the fen we find that our first impression of a 
brown meadow gives way to a more pleasant one, when we see 
that the growth consists of many marsh plants seldom found in 
such abundance. Conspicuous amongst these are sedges, reeds, 
yellow iris (Iris pseudo-acorus), yellow loosestrife (Lysimachia 
vulgaris), purple loosestrife (Lythrum salicaria), comfrey (Sym- 
phytum officinale), meadow-sweet (Spirea ulmaria), meadow rue 
(Thalictrum flavum), dwarf sallows, and hog’s-fennel (Peucedanum 
palustre), the food-plant of Papilio Machaon larvee. In addition to 
these plants are several rarer and interesting species, especially 
of the genus Ranunculus. As may be understood, the fen is 
frequently very wet, even in summer during some seasons. It is 
intersected with deep ditches, and surrounded by broader dykes, 
locally known as “loads.” On these may be seen the long narrow 
fen-boats laden with peat for fuel or with cut and dried sedge, 
which is used in the district for bedding for cattle or for thatching. 
The total extent of Wicken Fen is about three miles long by one 
mile broad. ' 
Should we, on our visit, have the bad luck to meet with wet or 
windy weather we shall fare badly with our captures. There is no 
shelter from the wind, which sweeps across the broad expanse of 
country with such force as to make flight impossible for all but 
the strongest insects. Should we, however, be more favoured 
with a warm sunny day any time between the end of June and 
end of July, we shall soon get a sight of the beautiful ‘‘ swallow- 
tail’ butterflies. 
When perfect insects are scarce we shall find plenty to 
occupy us at the various times of the summer season with 
looking for larvee. I will name a few of the many species we may 
expect, although, of course, not all at once, but each in its turn, 
which may be easily ascertained, On the sedges Orgyia cwnosa used 
