In Chapter 5 of All Quiet on the Western Front, are the lice symbolic?
I think a strong argument can be made that the lice in Chapter 5 are indeed symbolic of the men involved in war. Paul notes that "killing each separate louse is a tedious business when a man has hundreds", which brings to mind the grisly comparison of the difficulty of killing each of the many individuals which make up enemy forces. In order to make the job easier, Tjaden devises a contrivance whereby he rigs up "the lid of a boot-polish tin with a piece of wire over the lighted stump of a candle". The lice are thrown into the lid, where they are summarily eliminated.
In like manner, the powers that be engineer ever more efficient and deadly weapons of mass destruction. To overcome the tedious necessity of one-on-one killing, instruments are created to kill the members of the opposition en masse. Explosives, machine guns, and deadly gas are only some of the inventions whose sole purpose at the front is to kill large numbers of men in one strike. Like the lice, of which men are faced with hundreds at a time, soldiers must go up against hundreds of other individuals from opposing nations. It is much easier to use technology to eliminate them all at once, avoiding the inefficiency and tedium of having to take them on one at a time.
The symbolism even goes a step further, when Haie points out "a particularly fine brand of louse: they have a red cross on their heads". This entity parallels the presence of the Red Cross relief organization, which maintains a presence among the soldiers at the front (Chapter 5).