The Purple Emperor, now one of our rarest insects (I have not seen it alive since the time when I was a boy, and saw it around the oaks of Darenth Wood), was formerly captured by the aid of a net fixed to a pole 30 ft. or 40 ft. long. But accident or science discovered, however, that this wearer of Imperial purple possessed a very degraded taste, descending, in fact, from the tops of the highest oaks to sip the juices from any decaying or excremental matter. Now, therefore, the recognised bait is a dead dog or cat in a severe state of "highness." The "gamekeeper's museum" in the few places where Iris now resorts may be searched with advantage, yielding also a plentiful supply of beetles of various sorts. The "Holly Blue" I have noticed to have a similar degraded taste.
Mud holes also in hot weather attract many butterflies, as do the sweet exudations from various trees, or from fallen or over-ripe fruit.
Occasionally a high-flying insect may be induced to follow to the ground a stone or piece of turf thrown up in front of it. The persistent manner in which some species will return again and again to the very same spot is something wonderful. The same flower head, the same muddy puddle or patch of road, is selected. The collector, if foiled in his first attempt, will do well, therefore, to wait for the probable return of his prize. Certain species frequent the chalk district only, others woods and sandy lanes; some are found only high up in the mountains of the north, others but in the low-lying valleys of the south.
The sea coast has its specialities, some insects even flying well out to seaward, in crossing from land to land. I remember a "crimson-speckled footman" moth, Deiopeia pulchella, flying on board a steamship whilst we were fully a hundred miles from the nearest land. No place, in fact, should be disregarded in which to search for insects, for some are so exceedingly local that a district of perhaps twenty miles in extent may be searched in vain for a desired species, until the collector suddenly comes upon one or two fields swarming with them.
Nor is this all, for in the case of two or three extremely local species, but one or two spots in the British Isles are their favoured haunts. Bean fields in flower, clover and lucerne fields in sunshine, are first-class hunting grounds, whilst on cloudy or very windy days many butterflies, such as the Blues, may be found resting on grasses or on tree trunks in woods; or, as in the case of the Hairstreaks, higher up under the leaves. Beating the boughs with a long stick will often force insects to fly, when their presence is unknown to us.
I have hitherto spoken of the collecting of insects by day only, but as there are many insects — moths — which appear but at night, we must follow them to their haunts, prepared with lantern and net. In the dusk of the evening, just as the sun sets and twilight comes on, we must take our stand near the flowers frequented by certain moths. In spring the blue bell, cherry, and apple blossom may be watched.
Later on, the blossoms of lime trees, flowers of the honeysuckle, bramble, petunias, scabious, and a host of others. Nettle beds also are great hunting localities at this time of the evening for many moths. Dark and sheltered hedgerows of lanes, fields of mowing grass, willows near water, heather, the seashore, all add their quota to the persevering entomologist. The sallow blooms (commonly called "palm"), both male and female, must be searched early in spring time for the whole of the genus Taeniocampa and many other newly-emerged or hybernated species. As they usually drop at the first contact of the light from the lantern, the net must be held under them, or a sheet may be spread under the bush, and those which do not fall at first may be shaken off the blooms with a smart stroke or two of a stick. If the bushes are not high, "hand-picking" with the net held in readiness is really the best.
Ivy blooms in the autumn are also sure finds, several species — many of great rarity — being taken off this plant at night. Owing to the usual localities in which ivy is found, the spread sheet and subsequent "beating" come in more often than the safer method of "netting" and "bottling."
Light is also a great attraction to many moths, some of our greatest rarities being captured frequently, inside or outside street lamps, and the spectacle is by no means rare to see a "grave and reverend signor" climbing up the lamp-posts at a most unseemly hour of the night in search of specimens. Lighthouses have also yielded important captures, and there are worse things than being on friendly terms with the cleaner of street lamps, or the keeper of a lighthouse. True, you will get some awful rubbish, but the day will come when Alniaria or Celerio (which latter I once received alive), or some other rarity, will reward your faith. Light surfaces, such as white cloths or sheets left out all night, sometimes attract moths.
SUGARING. — The great nostrum for capturing moths is — "Sugar!" A legend tells that many years ago someone discovered (or imagined) that moths came to an empty sugar cask, situate somewhere in a now-unknown land; and acting as the Chinaman is said to have done, in re the roast pork — thought perhaps that the virtue resided in the barrel, and accordingly carted it off into the woods, and was rewarded by rarities previously unknown. A sage subsequently conceived the grand idea that the virtue resided in the sugar and not in the cask, and afterwards came the idea of an improved "sugar," made as follows: