5434 Insects. 



flies. Having been confined to the house, my next observation was made on the 27th 

 of September, when the number of caterpillars travelling and still feeding was much 

 diminished, though of the latter many of different ages were still to be seen. Some 

 preceding days had been cold. In a wide space closely examined I found only three 

 chrysalides of the mottled caterpillar, but several of smaller kinds. On the 1st of 

 October I was informed that the turnips in one particular garden of those under my 

 notice had been greatly infested by a small black caterpillar, of which I that day saw 

 a few elsewhere. These were, I believe, the larvae of a Tipula, and certainly the same 

 with those the performances of which I have before described (Zool. 336 — misprinted 

 326 at p. 4548), but, in the instances now noticed, they appeared to devour only the 

 tender parts of the leaves, whereas in the former case the entire tops of the turnips 

 were consumed. My last note is dated October 8th (my own hybernation having 

 commenced on the following day), when some few caterpillars were still in motion 

 upon their usual track, possibly a dozen and a half at most, the rape in the field being 

 clear of them, so far as examined by me. In the preceding autumn the insects were 

 numerous later than this day, but then the weather had been drier, in 1855 rain having 

 occasionally fallen very heavily, though not accompanied by much cold. The result 

 of what observations I was able to make in 1855 is, that caterpillars were more 

 numerous in that season than they had been in the preceding. I have related (Zool. 

 4546) that in 1854, when their next change was approaching, they ascended the walls 

 of a large house in incredible swarms; the irruption occurred again in the ensuing 

 year, when, however, more effectual preparations were made to meet the invaders. 

 Ichneumon flies abounded in 1854, being then, so far as noticed, only of one species, 

 and that very small ; whereas, in 1855, not only were they in much greater number, 

 but of several sizes. A friend, who resides in the very focus of the late visitation, 

 informs me that, of the multitude of caterpillars he crushed, five in every six were full 

 of maggot'. For my own part, I consider the proportion of fly-blown insects was even 

 much larger, and the activity of the ichneumons in pursuing their vocation was 

 remarkable, they being constantly in attendance wherever their proposed victims were 

 to be found. Once, upon the coping of a low wall, — a favourite track of the cater- 

 pillars, — I watched what I believe, from the spike at the end of the abdomen, to have 

 been a large ichneumon fly, — reddish black with red wings, — walk up to a "travelling" 

 caterpillar, pass its long antennae gently over the other's back for a few seconds, as if 

 in observation, and then turn away. The smallest of the flies, which appeared to be 

 by far the most abundant, were continually visible around and on the caterpillars, 

 especially when they became stationary for transformation, and, in many instances, 

 even upon the chrysalides, their presence evidently causing extreme annoyance, since 

 both the unchanged and the changed were incessantly moving their heads and tails 

 uneasily backwards and forwards, as if in vain endeavours to dislodge the enemy; the 

 consequence being, as I have reason to suppose, that, in one case at least, the 

 chrysalis broke from its moorings and fell to the ground. I have stated before (Zool. 

 4548) that I estimated the little maggots I had seen emerging from the body of a 

 single caterpillar " at two dozens at least." I am inclined now to believe the number 

 to have been still more considerable. Also, while in 1854 I supposed (Zool. 4548) the 

 small green caterpillars to have been untouched by the ichneumon flies, I strongly 

 suspect they did not escape equally well in 1855. Besides the hostility of their natural 

 parasites, the cabbage caterpillars were, in 1855, exposed to some other destructive 

 influence. My note of October 8th, reminds me how many discoloured (brown) car- 



