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[June-September 
be different from one with firm setae; and an interstitial inhabitant 
will be different from a subcortical or leaf-litter inhabitant. The 
point is that all of these kinds of organisms occur in Apterygota and 
all are among the most primitive known hexapods. 
In Diplura, grooming of the antennae, mid- and hindlegs involves 
at least fourteen cleaning positions, all of which appear to be 
satisfactory. This diversity is quite remarkable and is unequaled in 
other insects (Valentine, unpubl.). The grooming of dipluran fore- 
legs involves only one mode. The stereotypy of foreleg grooming 
contrasts sharply with the diversity of antennal, mid- and hindleg 
grooming. The logical explanation is that the single foreleg tech- 
nique works in most or all situations, while no one technique works 
for the other appendages. Environmental constraints appear to 
require that the insect reach and groom its antennae, mid- and 
hindlegs in several alternate ways. Diplura are basically interstitial 
organisms. Almost all specimens were found in the soil under 
undisturbed stones or boards, or in soil clods in gardens. A standard 
technique for finding campodeids was to break up the damp clods in 
a freshly plowed field or while digging potatoes. The very fine 
tunnels and cracks in this unyielding substrate are inhabited prin- 
cipally by small myriapods, Collembola, and Diplura. Since cam- 
podeids do not burrow and japygids do so very weakly (Pages, 
1967), they primarily use the interstices already present. In such a 
habitat body configurations are subject to an infinite diversity of 
living spaces. A grooming behavior possible in one crack may be 
impossible in another; however, a modification may work. We 
believe that the unequal grooming diversity in Diplura is a response 
to the problems of an interstitial life style. Foreleg grooming, where 
the leg is simply raised to the mouth, does not require any special 
bending or movement, so one technique does the job. Antennal, 
mid- and hindleg grooming require unusual movements of the 
appendage or of the body. Such movements may be limited by the 
varied configurations of the crawl space, and must accommodate to 
those configurations; thus, a variety of alternate positions appears 
to be a necessity. 
It is important to contrast the remarkable freedom of grooming 
positions of Diplura, with the very high degree of stereotypy in such 
orders as Diptera and Hymenoptera. The point is that a discussion 
of insect grooming based on Diptera or Hymenoptera is as biased 
towards stereotypy as a discussion of Diplura is biased towards lack 
