“Of the caterpillars, spiders, and other creatures which are supposed to fall from the trees into the water, and into the trout’s mouth, and of the consequent advantage of trees projecting over a stream; of the sapient advice, both verbal and written, to cultivate vegetation overhanging the river, because it increases the supply of natural food; of the statement that fish under trees are invariably in the best condition, anglers have heard from time immemorial. My advice is, cultivate your trees, because they are of advantage as giving shelter to the fish. Not a single example of these tree windfalls has been found in the hundreds of autopsies which I have made, and all the caterpillars and spiders that fall from the trees in a mile of water would not suffice to feed a single pound trout for a single day. They may therefore be discarded from consideration.”—Halford’s Dry-fly Entomology, page 138.

I read this passage with extreme surprise, as it absolutely contradicts my personal experience. After thinking the matter over carefully, and trying to make out how it was that Mr. Halford, in the hundreds of autopsies he has made, has never come across a caterpillar, I realised how dangerous it is to make a dogmatic and sweeping statement with the evidence of personal experience only to fall back upon.

As recently as June, 1897, when fishing with Dr. Charles R. Watson and Mr. A. D. Home, I made with them a series of six autopsies of trout caught consecutively in one morning. The smallest number of caterpillars found in one of these six autopsies was five, and the greatest, twelve. These trout were all caught under oak trees overhanging the water, which were at that time swarming with small caterpillars, most of these caterpillars being of a brilliant emerald green colour.

In the afternoon of the day on which I am writing this, Colonel Walker showed me a peculiar sort of knife which he carries when out fishing, for the purpose of making autopsies on trout. I naturally took advantage of this occasion to increase my evidence, and asked him if he had ever found caterpillars in the trout he caught. He told me that in certain places, in the early part of the summer, he almost always found caterpillars in the stomachs of the trout he caught under trees overhanging the water.

This experience of his exactly coincides with my own, though the six consecutive autopsies described above without my other similar experiences is a fairly strong piece of evidence. I am therefore inclined to believe that there is some good to be gained in following the sapient advice, verbal and written, to cultivate vegetation overhanging the river, beyond its advantage as giving shelter to the fish.

I will narrate the circumstances which first led me to use the caterpillar as a dry fly, as they may, I think, interest my reader.

I was lying on the bank by a large pool on a stream, and saw a little green caterpillar hanging from the branch of an oak tree, apparently trying in vain to pull himself up the thread by which he had so foolishly lowered himself, till he was uncomfortably near the surface of the water. I watched him, lazily thinking in a dreamy manner how very unkind it was of the trout to keep on rising, and yet not look at my fly. They were evidently feeding on something, but what it was I could not make out. The little green caterpillar was getting gradually nearer to the water, and I was beginning to think that the poor little chap would meet with a watery grave, when just as he touched the water a trout came up and grabbed him.

Little green caterpillars were evidently what the trout were feeding upon, and that was the reason that I could not catch one with a fly. I watched the branches of the oak tree overhanging the water for some time, and saw several caterpillars fall in and meet with the same fate. The next thing I did was to catch a caterpillar, scrape the fly dressing off my hook, and put him on it instead. I caught several trout in this way, but found that it was almost impossible to cast any distance without shaking off the caterpillar. After much trouble caused by this difficulty, which was very trying to the temper, as the caterpillars always seemed to come off the hook at the most critical moment, and having got a fairly good basket, I found it was time to return. That night I managed to make some fairly good imitations of the little green caterpillar to use on the morrow, instead of the natural ones. These imitations met with success, and since that time I have been able to improve on the dressings then used.

I have found many different kinds of caterpillars in the stomachs of trout, but small green ones of various sorts were decidedly the most numerous. The species I have most frequently found is, I believe, the larval form of the Tortrix viridana. I have never found a large caterpillar in a trout, though I have caught trout with imitations of them used as dry flies. I give the exact dressing of the green caterpillar; but the other dressings must be left to the discretion of the fisherman for alterations, as there are so many sorts of small caterpillars, some of them being extremely rare in one place and common in another.

Should the fisherman wish to see the sort of caterpillar commonest where he is fishing, he must seek them himself. Those only are useful which are on the trees overhanging the water. If there are oak trees the caterpillars will probably be green, and many kinds of caterpillars will be found which have rolled themselves up in the leaves of the tree upon which they live. I have no doubt that this imitation caterpillar will be looked upon as a poaching implement, but it is or should be used as a dry fly, and to use it successfully requires as much skill and power of observation as does the use of any imitation of a fly used in a similar manner.

How to make an Artificial Caterpillar.—A small piece of cork 1/32 of an inch thick, or less, and nearly twice the length of the hook, must be cut into the shape shown in Fig. 17. Next take a piece of quill rather longer than, and about the thickness of a large pin, from a tail or wing feather of a starling. This quill makes the foundation of the body. Split the thick end of the quill far enough to embrace two-thirds of the shank of the hook, and then tie it on the hook as shown in Fig. 18. Now fold the piece of cork, with the broad end towards the eye of the hook, over the shank of the hook and the quill, tying it in as shown in Fig. 19.

This foundation serves for any caterpillar. Tie it at the tail whatever is to be used for ribbing the body, and the body material if it is not to be spun on the tying silk. Then wind on the body material, tie it in, wind on the ribbing, finish off at the head, and cut off the projecting piece of quill.

The caterpillar when finished should appear as shown in the illustrations on Plate III.

Green Caterpillar.—1. Emerald green wool spun on tying-silk, ribbed with light yellow silk.

2. Emerald green wool spun on tying-silk, ribbed with scarlet silk.

3. Yellowish green wool spun on tying-silk, ribbed with narrow gold tinsel.

4. Olive green wool spun on tying-silk, ribbed with narrow gold tinsel.

(I have found Nos. 1 and 2 very successful when ribbed also with narrow gold tinsel, and Nos. 3 and 4 when ribbed with light yellow silk.)

Other Caterpillars made with a reddish-brown body, and ribbed with yellow or red, are also sometimes very successful, as are those also ribbed with red or Coch-y-bondhu hackles.

PLATE III

ARTIFICIAL FLIES

Drawn from flies tied by Mrs. J. R. Richardson, of Kingston-on-Thames (dressed from the Author’s models).