TORRINGTON HOUSE, ST. ALBANS, _January 26, 1888_.
Many thanks for your note received this morning. I shall hope to add some of it to my Turnip Caterpillars paper, which is not yet gone to press. Thank you for the offer of the specimens, but I do not quite see my way to showing live ones yet. My lecture [at the London Farmers’ Club] is a terribly anxious prospect to myself, but I can but do my best, and I am endeavouring with the utmost care to form something that may be acceptable, but I am sure you will believe me that to address such a skilled audience is rather anxious work. I should much like to lay before the members of the Club some ideas for their consideration as to how some reasonable amount of plain serviceable information might be got abroad. I do not believe in all this lecturing, examining and talking of classification. To my thinking it is beginning at the wrong end, and that the learners need first to make sure of their facts in the field and classify them when they have got them, if they do it at all.
FIG. 2.—WOOD LEOPARD MOTH, _ZEUZERA ÆSCULI_, LINN. ]
I have examined your caterpillars carefully, and I find that of the oak stem to correspond exactly with the larva of the Wood leopard moth, the _Zeuzera æsculi_. This is commonly found in (or at least it is usually sent me from) wood of fruit trees, but it attacks oak as well as forest trees of various kinds. Your specimen has also one of the characteristic habits of ejecting brown fluid from its mouth on disturbance. I think you have my “Manual,” and there you would find a figure of the moth and larva. Your specimen is rather full coloured, but they vary greatly in this respect.
Your other caterpillar is a Lepidopterous larva, but I cannot name it with certainty. It is quite possible that it is the larva of the “Hornet Clearwing,” the _Trochilium_ (= _Sesia_) _bembeciforme_, but I have never seen a specimen, although the attack is said to be common, especially to _Salix caprea_. The attack is stated to be mostly in the lower part of the stem. I think that you very likely have Loudon’s “Arboretum” in your library, and if so you would find some good notes and fair figures of the hornet-like moth and its larva and pupa _in situ_ in the wood at pp. 1481 and 1482, vol. iii. The larva is nearly dead now, so that the form is altered, but I do not see any reason against it being this kind; still I cannot say it is.