THE ENTOMOLOGIST. 151 



of this insect, and I openly express ray thanks to him on 

 that account. This gentleman furnished me with sixty of 

 these eggs, together with the female fly which had laid them. 

 On the 8th July all the caterpillars appeared. Five or six 

 days before the caterpillar comes out the egg begins to 

 change colour only, and becomes dark brown at the place 

 where the head of the caterpillar is, then again slowly brighter, 

 and at last as clear as glass, so that the grub is seen in it most 

 plainly; and I have pictured it at fig. 2, as it appears under 

 a good magnifying-glass. Not less plainly is seen the move- 

 ment of the dark spot under the head, which is the mouth of 

 the caterpillar. The little animal is then trying to make a 

 little hole in the top of the egg, and as soon as this is big 

 enough for it to put its head through, the little caterpillar 

 creeps out of it. Just after it is born it is of a yellow colour, 

 with a dark brown head, and has a white horn bent forward 

 on its tail, but this shortly afterwards becomes coal-black, 

 and is split above on the point, or rather it has there two fine 

 little points, which anyone who is sharp-sighted can see with 

 the naked eye. This just-born fir-tree arrow-tail grub is 

 shown at fig. 3. Most of these little caterpillars, after they 

 are hatched, let the empty egg-shell lie, without making any 

 further use of it; some, however, ate it up greedily; some 

 even were not satisfied with their own egg-cover, but con- 

 sumed also those of others. After consuming this breakfast 

 the fir-tree needles are afterwards their special food, when, 

 being still young, they feed in the manner aforesaid, like the 

 caterpillar of the Anomalus fly (Fidonia Finiaria), in that they 

 eat more at the edges of the spines, but afterwards, when they 

 have become older and bigger, they eat them off cross-wise, 

 beginning from above at the point and going thus down, 

 leaving often a morsel of the spine at the foot. The growth of 

 this caterpillar lasts above four weeks, within which time they 

 moult four times, usually about every six or seven days: at 

 each moult they eat up all the cast-off skins. After the first 

 change the caterpillar appears striped with green, like fig. 4 ; 

 after the second and third moults the stripes become longer 

 and more distinct, and the little horn still remains forked at 

 the point, as is pictured at fig. 5, magnified ; but after the 

 fourth, or last change, the rosy stripe on the back and the 

 narrow black rings first come in sight. Ihe liitlc horn, 



