He buildeth his house as a moth. The moth is the symbol of fragility, decay, and weakness. The wicked man's attempt to build himself up a house, and establish a powerful family, is no better than a moth's attempt to make itself a permanent habitation.
As moths do not construct dwellings for themselves, it has been proposed (Merx) to read כעכבישׁ, "as a spider," for מעשׁ, "as a moth;" but the change is too great to be at all probable. May not the cocoon, from which the moth issues as.
from a house, have been in Job's mind? The hawk-moth buries itself in a neat cave for the pupa stage; and there may have been even better examples in Uz. But we ourselves have not known these facts long, and therefore we need not be surprised to find Job making a mistake in natural history.
And as a booth that the keeper maketh. Huts or lodges of boughs were set up in vineyards and orchards by those who had to watch them (see Isaiah 1:8; Lamentations 2:6). They were habitations of the weakest and frailest kind.