286 
Beetles 
SECTION TRIMERA. 
Only one family is included in this section of beetles with but three tarsal 
segments in each foot, namely, the familiar little ladybirds or plant-louse 
beetles, the Coccinellidae. Their uniformly small size, the semispherical shape, 
and the “polka-dot’’ pattern distinguish them readily from all other beetles 
except perhaps the Chrysomelidse, a few of which are often mistakenly 
called ladybirds. This is a particularly unfortunate confusion because of 
the radically different food-habits and consequent economic relation to 
man of the two families. The Chrysomelidse, or leaf-eaters, both as larvae 
and adults, attack our crops and trees and flowers; the Coccinellidae, or 
ladybirds, both as larvae and adults, feed on plant-lice and scale-insects, 
great enemies of our orchards and gardens,- and thus are among our best 
insect friends. A friend of mine found that his roses were suffering from 
insect attack; he saw little, convex, black-spotted reddish beetles clamber¬ 
ing busily up and down the stems, and he set to work to pick these off one 
by one and drop into a tin cup with petroleum in the bottom. When he had 
Fig. 397. —Some Californian ladybird-beetles; beginning at left of upper row the species 
are Megilla vitigera, Coccinella californica, C. oculata, Hippodamia convergens; 
beginning at left of lower row, Coccinella trifasciata, C. sanguinea, C. abdominalis, 
Megilla maculata. (Twice natural size.) 
a full pint he showed them proudly. But the more little round beetles he 
picked off the more rapidly wilted his roses. And for the wholly sufficient 
reason that he was collecting and killing the ladybirds that were making 
a fight—a losing one in the face of my friend’s active part in it—against 
the hosts of tiny inconspicuous green rose-aphids that were sucking the sap 
out of the rose-stems and buds. So be it remembered that not all bugs 
are bad bugs, but that some, like the ladybirds, are most effective helpers 
in waging war against the real pests! 
There are about 150 species of ladybirds known in the United States,, 
and almost all are reddish brown with black dots or black with reddish 
