METAZOA INSECTA. 443 



Most of the Cerambycidae are tree-borers in the larval 

 stage and the young live in narrow galleries where there 

 is little need of feet. These organs, therefore, are re- 

 duced in size so that they are not seen from above (PI. 

 1 12 1, fig. i, Orthosoma brunneum De Geer), but only in 

 a ventral view (fig. 2, probably the same species). 



The structure of these small thoracic legs is better 

 shown in PL 1122, fig. 2, which is the limb, greatly 

 enlarged, of the oak pruner, Elaphidion villosum Fabr. 

 (No. 1123; PL 1122, fig. 5). The larva (fig. i) burrows 

 in the wood under the bark and packs the burrow with 

 its sawdust-like castings. It selects, as a rule, a small 

 twig consuming the wood in such a way that the winds 

 easily sever the twig so that it falls to the ground with 

 the larva. The opening at the severed end the larva 

 plugs with castings and in this closed cell transforms to 

 a pupa (fig. 3, longitudinal section of twig; fig. 4, cross 

 section of same) which in a shorter or longer time, ac- 

 cording to temperature, changes to a beetle that cuts its 

 way out through the plug of castings. 



Some of the Cerambycidae have footless grubs like the 

 Saperda Candida Fabr., or the round-headed apple-tree 

 borer (PL 1124, fig. i, dorsal view; fig. 2, side view). It 

 feeds when in the larval state upon the sap-wood, but by 

 the end of the second year it reaches the solid heart-wood. 

 The third year the larva gnaws outward to the bark and 

 makes a cell for itself. Here the pupa (fig. 3) transforms 

 to the adult (No. 1125.; PL 1124, fig. 4) which cuts its 

 way out of the tree by its sharp mandibles. 



Chalcophora virginica Drury (No. 1126), of the family 

 Buprestidae, is another species with footless larvae. These 

 live in the pine and have the forward part of the body 

 broad and flat. The adults have brilliant metallic hues 

 (see No. 1127, ventral side of same species). 



The Ambrosia beetles of the Scolytidae are interesting 

 forms, since, according to Hubbard, 1 they exhibit charac- 



1 U. S. Dep. Agric., Bull. Div. Ent., n. s., no. 7, 1897, p. 9. 



