188 INTRODUCTION 
of a butterfly, but of course incapable of being rolled up.’ H. Hagen (Proc. Soc. 
Nat. Hist., Boston, xx, 1880, pp. 429-30) states that twenty-six species of Nemognatha 
with thread-like maxillae are known in America. 
These species, as well as perhaps the foreign genus Chauliognathus Hen/z. 
(Telephoridae), with extraordinarily elongated stalk-like maxillae, and possibly also 
some of the Euchiridae and Hoplidae, are placed by Loew among the /emztropous 
flower visitors. All our indigenous beetles are allotropous or dystropous. 
Loew describes as allotropous (‘ Blumenbesuch,’ II, p. 140) :— 
(2) Constant flower visitors with distinct structural adaptations for procuring 
sap, and heterobiotic larvae (Lepturidae, Oedemeridae, some Cantharidae and 
Lycidae). 
(4) Constant flower visitors with indistinct or no structural adaptations for 
procuring sap, and heterobiotic larvae (Melyridae, Mordellidee, some Cistelidae, 
Cleridae, Buprestidae, and Elateridae). 
(c) Flower visitors evolved from dystropous forms, with distinct structural 
adaptations for procuring sap, and with heterobiotic larvae (Cetoniariae, Trichiariae). 
(7) Constant flower visitors with homobiotic larvae (Phalacridae, some ° 
Nitidulidae). 
(¢) Occasional flower visitors, of primarily carnivorous habit (some Cleridae, 
Coccinellidae, and Staphylinidae). 
(/) Occasional flower visitors, of primarily saprophagous or xylophagous habit 
(some Dermestidae and Ptinidae). 
According to Loew (op. cit.) the following are dystropous :— 
(z) Curculionidae, with proboscis. 
(4) Lamellicornia, with toothed maxillary lobes (Melolonthidae). 
(c) Chrysomelidae, with pronounced homobiosis of larvae and adults. 
According to my statistical investigations (‘ Bliitenbesucher,’ II, p. 11), the allo- 
tropous beetles occur in by far the greatest abundance on flowers with exposed 
nectar, which are best adapted to their short proboscis, but they also visit flowers 
with half-concealed nectar. The more deeply placed nectar of the other classes of 
flowers is beyond their reach, Their marked preference for pollen induces them not 
only to visit pollen flowers diligently, but also to devour this sort of food in the 
blossoms of other classes, especially in social flowers, where it is especially abundant. 
Loew’s results (‘Blumenbesuch,’ II, p. 144) agree with this—Flowers with com- 
pletely concealed nectar, bee flowers, and lepidopterid flowers, are visited only to 
a small extent by such unskilled flower guests as beetles, and such visits are as 
a rule merely destructive. Pollen flowers and anemophilous flowers are much more 
frequently sought out, as they afford welcome food to many beetles. Insects of this 
order mostly affect flowers with exposed nectar and those which are social, the 
former on account of the accessibility of their nectar, and the latter because they are 
rich in pollen. 
In the Alps (Miiller, ‘Alpenblumen,’ p. 513) the visits of beetles to flowers are 
divided on the whole very impartially between the different groups, which is to be 
explained by the fact that many of them not only lick nectar or eat pollen, but also 
devour any delicate floral structures. But even among them there appears to be 
