The Moths and Butterflies 
37 1 
by collectors and nature students. But these moths are of particular impor¬ 
tance and interest to entomologists because they are undoubtedly the oldest 
or most generalized of living Lepidoptera; they represent most nearly, among 
present-day existing moths, the ancestral moth type. This is shown most 
conspicuously by the similarity in size, shape, and venation of the fore and 
hind wings, for the primitive winged insects had their two pairs of wings 
equal, while nowadays the various orders show a marked tendency to 
throw the flight function on one pair, either the fore wings, as among the 
flies (Diptera), wasps, bees, etc. (Hymenoptera), and Lepidoptera, or the 
hind wings, as with the locusts, crickets, etc. (Orthoptera), and beetles (Cole- 
optera), the other pair becoming much 
reduced in size, or even, as in the 
Diptera, wholly lost. Quite as impor¬ 
tant, if not more, although not so con¬ 
spicuous, as an evidence of the ancient 
character of the jugate moths, is the 
condition of the mouth-parts, certain 
species in the group having true biting 
mouth-parts, with well developed man¬ 
dibles, short lobe-like maxillae, and short, 
truly lip-like labium. All other moths 
and butterflies have the mouth-parts 
specialized for sucking, with the man¬ 
dibles rudimentary or wanting, the max¬ 
illae produced and apposed to form the 
long flexible sucking-tube, and the under 
lip (labium) reduced to a mere immovable 
functionless sclerite. The presence of 
the jugum for tying the fore and hind 
wings together, as in the caddis-flies, 
undoubtedly nearly allied to the moth 
ancestors, instead of the specialized 
frenulum as in other moths, is also evi¬ 
dence of the ancestral type displayed by 
the Jugatae. 
The Micropterygidae, represented in 
this country by two genera, Eriocephala, 
with four species, and Epimartyria (Micropteryx), with two species, are among 
the smallest moths we have, the largest not expanding more than one-third 
of an inch and the smallest only one-fifth of an inch, the body being about 
one-tenth of an inch long. They are indeed almost invisible when flying, 
and are only very rarely taken by collectors. They fly in the sunshine, 
Fig. 524. —Diagram showing venation 
of wings in monarch butterfly, Anosia 
plexippus. c., costal vein; sc., sub¬ 
costal vein; r., radial vein; cu., cubi¬ 
tal vein; a., anal veins. The base of 
the medial vein (lying between radius 
and cubitus) is obsolete, but its 
branches still persist, lying between 
branches of radius and cubitus. 
(Natural size.) 
