1987] 
Deyrup & Eisner — Mimicry 
217 
top). At one location in a dense stand of H. subaxillaris covering an 
area of about 50 X 50 m, we counted 250 specimens of G. francilloni 
and 6 of M. comata. The meloids often occurred in groups of 2 or 3 
(31 pairs were in copula ), while the mordellids occurred singly. 
Visually, as small specks of reddish-brown and black on the brilliant 
yellow floral discs, the two species are difficult to distinguish. The 
differences apparent at very close range were not obvious to us at a 
distance. We had long been familiar with Gnathium at our field site 
before we noticed the Mordellistena among them. 
Nemognathines can be expected to be protected chemically by 
cantharidin, the well-known terpenoid toxin present in meloid 
blood (Carrel and Eisner, 1974). Meloid beetles typically reflex- 
bleed when disturbed, a behavior that we could readily induce in G. 
francilloni, as in other species of Gnathium, by gentle pinching of 
the body and legs. M. comata, we believe, may avoid harassment 
through mimicry of these protected models. Whether it is itself fully 
palatable and therefore (in a chemical sense) a Batesian mimic, 
remains unanswered. The literature offers no clue to the presence of 
chemical defensive agents in mordellids. Tests that we did with 
another species of mordellid, Mordella atrata (Melsheimer), proved 
this beetle to be edible: six individuals (freshly killed or rendered 
moribund by freezing) that we offered at our field site in a small dish 
to tame wild scrub jays ( Aphelocoma c. coerulescens) were taken in 
quick succession by one bird, together with pieces of peanut offered 
as accompanying morsels. The same bird ate another 29 of 32 M. 
atrata that were similarly offered several days later, and a second 
bird ate two individuals of this lot, leaving only one of the beetles 
uneaten. 
Examination of G. francilloni and M. comata by ultraviolet 
video-viewing (Eisner et al. 1969) showed no differences in ultravi- 
olet reflectance characteristics. Both beetles are ultraviolet absor- 
bent over their entire body surface. To the insect eye, therefore, the 
beetles should also appear similar in coloration. 
M. comata and G. francilloni have more or less overlapping geo- 
graphic ranges, according to the fragmentary data available (Black- 
welder and Arnett, 1975). There are additional species of meloids, 
such as Nemognatha nemorensis Hentz, and one additional mordel- 
lid, Mordellistena marginalis Say, that occur on flowers and seem to 
belong to the red-pronotum, black-elytra mimetic complex. At the 
Archbold Biological Station this general complex includes about 90 
species, belonging to various insect orders; most of these species 
