1971] 
Hlavac — - A ntenna Cleaner 
61 
segments just cleaned which are in the channel above the setal band. 
From the channel, the proximal segments curve broadly to the 
antennal insertion. Only rarely are both antennae cleaned simul- 
taneously. 
In PristonychuSj the proleg is lowered on the extended antenna. 
The large clip setae engage the antenna and press it against the 
setal band (Fig. 35). The antenna is drawn through the cleaner 
by the proleg’s posterior movement, which is generated by coxal 
rotation, as well as by dorsal movements of the head and thorax 
(Fig. 36). During cleaning, the antenna is not bent and the apical 
segments do not touch the substrate. 
In both species, the protibial antenna cleaner is rubbed against the 
mesotibia after grooming the antenna several times. Occasionally 
the protibia is drawn through the mouth parts. The meso- and 
metatibia bear grooming setae. Fragmentary data indicate that a 
grooming system involving, in part, anterior movement of particulate 
matter to the protibia where it is ingested may be present in carabids. 
Such a system is known in ants (Sudd 1967). 
Only about half the surface area, but most of the sensory regions, 
of a flattened antennal segment can come in contact with the band 
setae during a single act of grooming (Fig. 5 SE). Rotation of the 
antenna through movement of segment one could permit the other 
half to be cleaned. 
Discussion. The effect of grooming on cuticular surfaces in cara- 
bids and other insects is poorly known. Particulate matter is, of 
course, quickly removed. The metapleural gland in ants secretes a 
material with antibiotic properties that is spread over the body sur- 
face by grooming (Maschwitz, et al, 1970). The association of 
single cell glands with antenna cleaning setae and other grooming 
bristles in carabids and other forms suggests that more than me- 
chanical removal of detritus is involved in grooming. In any case, 
until these grooming functions become known, it would be useless 
to speculate on the specific selection pressures that have led to the 
development and differentiation of the carabid antenna cleaner. The 
arguments for biological improvement to be developed below are 
based on differences in mechanics, not on differences of ultimate 
function. The conclusions drawn from such observations are first 
approximations. 
The grade C antenna cleaning mechanism is an improvement over 
the grade A type. For effective cleaning, the width of the antennal 
segment being groomed should be parallel to, and lie snugly against, 
the setal band, as in Fig. 5. If otherwise, only part of the surface 
