THE GROUND BEETLES. 



37 



the basal ones) covered with a minute pubescence ; epimera and epi- 

 sterna of thorax distinct; abdomen with six, rarely {Brachinini) 

 with seven ventral segments, the first visible only at the sides ; legs 

 slender, the hind ones not very different from the middle pair ; 

 front and middle coxa? globular, hind coxae dilated on the inner 

 side; tarsi 5-jointed. 



The majority of the species of Carabida? are predaceous and 

 beneficial, feeding in part upon the larva? and mature forms of 

 other insects'; their mouth parts being excellently adapted to catch- 

 ing and masticating such food. Dr. S. A. Forbes examined 175 

 specimens representing 38 species and 20 genera. Of these 83 speci- 

 mens, obtained in miscellaneous situations, had derived 42 per cent, 

 of their food from the animal kingdom, while of 70 specimens taken 

 in an orchard where canker-worms were, abundant, 77 per cent, of 

 their food was of animal origin, 21 per cent, being canker-worms. 

 Of the 175 specimens examined, 57 per cent, of the food was of ani- 

 mal origin, 36 per cent, being composed of the remains of insects; 

 the other 21 per cent, being made up of mollusks, earthworms, myra- 

 pods and arachnida?. The vegetable matter eaten was composed of 

 the remains of cryptogamic plants and the pollen of grasses and 

 Oomposita?.* 



A few members, especially those belonging to the genera Har- 

 palus, AnisodactyUis and Amara, are seed eaters and probably do 

 more damage than good ; while the larva? of Omophron and some of 

 the species of Clivina have been known to be quite destructive to the 

 soft sprouting grains of corn. However, on account of their great 

 numbers and predaceous habits, both in the larval and perfect 

 stages, our Carabida^ doubtless play an important part in holding 

 in check the excessive multiplication of other and more injurious in- 

 sect forms. 



The larva? of the Carabida? are mostly long, flattened grubs, 

 with the body of nearly equal breadth throughout. They 'have sharp 

 projecting mandibles and the hind end of the bodv bears a pair of 

 conical bristly appendages. Like the adults they are predaceous, 

 living in burrows just beneath the surface of the ground, and feed- 

 ing upon the soft bodied larva* of many leaf eating insects which 

 enter the ground to transform. "When fully grown they change to 

 pupa 1 under ground in small earthen cells which thev form for this 

 purpose. When ready to emerge as imagoes, the color changes 



*"The Food Relations of the Cirabidi© and Qaccinellidaj," in Bull, No. 6, 111, Lab, Nat, Hist, 1883, 



