150 THE ENTOMOLOGIST. 
the caterpillars of the fir-tree arrow-tail moth. I cannot well 
express with words how delighted we were, and the more so 
as we supposed that this insect did not dwell at all in this 
country, but, as we knew already, in Germany. We founda 
small caterpillar on a fir-leaf, and observing that it had a 
horn on the tail we could come to no other conclusion but 
that it must be the caterpillar of the fir-tree arrow-tail moth, 
although somewhat pale; the smallness of the caterpillar 
showed that it had not escaped from the egg many hours. 
Through this new discovery, uncommonly encouraged, we 
became very zealous in searching for this insect, and found 
several of its eggs, but these were, to our sorrow, impregnated 
with strange eggs, and consequently perished: another new 
discovery,—a very strange phenomenon,—at which we won- 
dered not a little; for that the caterpillars should be impreg- 
nated with eggs of wasps and flies, and thus become destroyed, 
was a well-known fact, but that the eggs also of some flies 
should have to submit to this lot seemed to us paradoxical 
and incomprehensible. I shall, further on, speak more on 
this subject, but must now consider the history of this insect. 
After some search we found other two of these caterpillars, 
the one much greater than the first and probably already 
twice changed, the other nearly full grown. These three cater- 
pillars having been fed carefully with the fir-leaf, and having 
grown large, we saw, to our great delight, that towards the 
end of September two of them crept into the earth and 
became pupe, but the third died still young. The two pupe 
remained all winter in the ground, and on the 6th Jaly 
following there came out of the one a beautiful and lively 
moth, but the other brought forth a so-called bacon-eater 
(being a certain kind of wasp), with whose eggs this cater- 
pillar had been impregnated. 
§ 2.—The complete house-holding of this insect, from the 
very egg to the last or flying state, was now sufficiently 
known to us, except that we had not yet seen any undamaged 
eggs; but in the year 1767, on the 12th July, we found two 
good eggs, out of which the caterpillars came on the 21st of 
the same month, which we brought up until they were 
almost full grown, when, however, they died. But in the 
following year, 2nd July, a great and eminent amateur gave 
us a still better opportunity of observing the house-holding 
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