40 THE ENTOMOLOGIST. 
looking object was alive. When the time comes for the larva to 
moult for the last time, it is then too large to any longer hope to 
deceive the eyes of its enemies under its previous disguise, and 
accordingly a complete change takes place. All this time it has 
possessed on the second segment four indistinct hairs—two on each 
side ; and on the remaining segments two—one on each side. 
Now, on assuming its final coat, the hairs on the second, 
third, fourth, fifth, sixth, seventh, eighth, tenth, and eleventh 
segments are magnified considerably, being now about the thick- 
ness of a horse-hair, and at the tip of each, presenting the 
appearance of having been hammered flat, the hairs on the other 
segments remaining rudimentary. These hairs, and especially 
the double number on the second segment, give the larva the 
most formidable appearance imaginable. 
In other respects the body changes in a very remarkable way 
to a ground colour all over of the most intense metallic green, 
identical with that so familiar to all of us on the wings of Z. fili- 
pendule; while on each segment after the head there extends 
laterally a broad rectangular streak of bright yellow. This com- 
bination of colour,—the dark green and bright yellow,—together 
with the flat-tipped bristles, unites to give one that uncomfortable 
sensation we all experience on seeing a wasp in too close 
proximity. To this form I give the name Sematic* (cnua, a 
warning). 
But the bristles have not yet done all their work. When 
the time comes at which the larva intends to undergo its 
change to a pupa, it descends the tree, and singles out some nice 
rotten stick lying on the ground, and this it excavates with its 
powerful mandibles. In this process of excavation,—and in 
the case of one larva I watched the process for four hours on 
end,—much sawdust is formed; and as the work advances, and 
the larva gets farther and farther into the wood, he finds it 
necessary to retract his body, every now and then, to sweep out 
this obstruction, and in this action the flat-tipped bristles are of 
the utmost service, for each bristle as it comes out brings along 
with it one, two, or three fragments of wood, and, of course, 
“every little helps.” It is extremely interesting to watch this 
process of excavation going on. When the larva considers he 
has dug in far enough, he sets himself to widen his domicile ; 
and when he has made it roomy enough to turn completely 
round in,—a work in which the bristles come in useful again, 
—he enters it finally, and, after a thorough sweep out, reserves 
the last few fragments of wood, and with them spins a slight 
web in the aperture of his retreat, and then resigns himself 
to internal and external metamorphosis, after which he les quiet 
till the ensuing June brings him out a perfect insect. 
* This designation is borrowed. 
