KEPT BY ANTS. 75 
fig. 5). It is an active bustling little being, and I 
have kept hundreds, I may say thousands, in my 
nests. They run about in and out among the ants, keep- 
ing their antenne in a perpetual state of vibration. 
Another very common species is a sort of white wood- 
louse (Pl. V. fig. 7), which enjoys the rather long name 
of Platyarthrus Hoffmanseggii. André only mentions 
Platyarthrus as living with Formica rufa, Myrmica 
scabrinodis, and Leptothorax acervorwm. I have 
found it also with Lasius niger, L. flavus, and F. 
fusca. It runs about, and is evidently at home, 
among the ants. Both Platyarthrus and Beckia, 
from living constantly in the dark, have become 
blind; I say ‘have become,’ because their ancestors 
no doubt had eyes. In neither of these cases have I 
ever seen an ant take the slightest notice of either of 
these insects. One might almost imagine they had 
the cap of invisibility. 
It is certain that the ants intentionally (if I 
may so say) sanction the residence of these insects 
in their nests. An unauthorised interloper would be 
at once killed. I have, therefore, ventured to suggest 
that these insects may, perhaps, act as scavengers. 
In other cases the association is more close, and the 
ants take the greatest care of their guests. 
It appears that many of these insects produce a 
secretion which serves as food for the ants. This is 
certainly the case, for instance, with the curious blind 
beetle, Claviger (Pl. V. fig. 8), (so called from its club- 
