318 the study of insects . 
clothed. The palpi are short, usually but little developed; 
and the maxillae are present. The most important features in 
the venation of the wings (Figs. 386, 387) is the union of 
veins V 2 and V, of the fore wings with cubitus, making 
it apparently four-branched ; and the growing together of 
subcosta and radius of the hind wings for a considerable 
distance. The extent of the union of these two veins varies 
greatly in the different genera; but so far as we have ob¬ 
served it is always less 
than four fifths of the 
length of the discal 
cell. This character is 
of use in separating 
these insects from the 
t 
Zygaenidae in which 
the union of these two 
veins is carried farther. 
The larvae of the 
Tiger-moths are clothed 
with dense clusters of 
hairs. In fact a large 
proportion of our com¬ 
mon hairy caterpillars 
are members of this 
family. I11 some species, certain of the clusters of hairs 
are much larger than the others, resembling in this 
respect the clothing of the Tussock-moths. Most larvae 
of the Arctiids feed upon herbaceous plants, and many 
species seem to have but little choice of food-plant; 
but certain common species feed upon leaves of forest- 
trees. 
About one hundred and fifty North American species 
have been described. The following are some of the more 
common representatives. 
Among the more beautiful of the Tiger-moths is a genus 
the species of which are snow-white or light yellow with the 
