Remembering this, it is interesting to note how differently the tiger-beetle (Cicendela) behaves when hunting the powerful harvesting ants and when preying upon the weak little Formica (Tapinoma) erratica; for, while it seizes the latter without taking any precautions, it is evidently more than half afraid of the former.
I have seen this beetle lying in wait near a train of structor or barbara ants, watching until some individual separated a little from the main body, when it would rush forward and make a snap at it, retiring again as quickly as it came. If the tiger-beetle fails to seize its prey exactly behind the head it will let it go again, and two or three ants are often thus cruelly mutilated before a single one is carried off.
No doubt the beetle has learned that if once this ant clasps its mandibles upon either antennæ or legs, nothing, not even death itself, will make it release its hold. It therefore tries to pin the ant in such a way that it cannot use its formidable jaws. Perhaps the habit of forming long compact trains may have been acquired by the ants partly with a view to guarding against attacks of this kind.
The colonies of the little F. erratica, on the other hand, apparently have to trust to their habit of working under the covered ways which they construct, as well as to their activity and great numbers for their preservation.
I had thought that the very powerful, and, to me, disagreeable, odour of these little ants might have rendered them distasteful to the tiger-beetle, but this is evidently not the case.
I have said above that, as far as our present know-
