6 BULLETIN 437, U. S. DEPARTMENT OF AGRICULTURE. 



12. Dorsal marking an inverted Y with a depressed shining reticulated diamond- 



shaped area surrounding the apex (PL IV, fig. 2) Trachykele. 



Dorsal marking an inverted V with a broad reticulated apex (PI. IV, fig. 1) 



Dicerca. 



13. Dorsal plate rather small, oval or egg-shaped, marked by a distinct brownish 



median groove which is goblet-shaped in front and forked behind; 

 a pair of brown spots on the median subdorsal areas of the second and 



third segments (PI. IV, fig. 3) Thrincopyge. 



Dorsal plate large, covering most of the dorsal surface, marked by a distinct 



simple median groove sometimes broadening in front (PI. IV, fig. 4) . 14 



14. Ventral plate with a median dark line, both plates slightly corrugated longi- 



tudinally, a dark brown sunken spot on either side of the head near 

 the base of the mandible, a pair of brown spots on posterior subdorsal 

 areas of third segment and a pair on anterior ventral area of fourth 



segment (PI. IV, fig. 4) Polycesta. 



Ventral plate with simple median line or groove, no sunken spots (PI. V, 



fig.l) 15 



15. Fourth segment narrower than fifth (Pi. V, figs. 1,3) 16 



Fourth segment broader than fifth (PI. V, figs. 2,4) 17 



16. Grooves of first segment light, plates not whitish opaque (PI. V, fig. 1) 



Chrysophana. 



Grooves of first segment dark brown, plates whitish opaque (PI. V, fig. 3) 



„ Ptosima. 



17. Third segment narrower than second (PI. V, fig. 2) Acmaeodera. 



Third segment wider than second, appearing nearly as large as first (PI. V, 



fig. 4) Tyndaris. 



18. Dorsal plate marked by two moderately separated dark brown lines which 



converge anteriorly (PI. VI, fig. 1) Eupristocerus . 



Dorsal plate marked by a single median bisecting line (PI. VI, fig. 2) Agrilus. 



19. First segment as broad or slightly broader than the following, body gradually 



tapering to the twelfth, slightly wedge-shaped (PI. VI, fig. 3) Brachys. 



First segment narrower than the following, body tapering both ways from 

 about the middle, more acute at the posterior end, spindle-shaped 

 (PI. VI, fig. 4) Pachyscelus. 



Note. — The author will be glad to determine specimens of "flat-headed borers," and for anyone, if the 

 locality and host plant are given. Such specimens should be sent to Forest Insect Investigations, Bureau 

 of Entomology, Washington, D. C. So far as known no larvee of the genera Gyascuius, Hippome.as, Agaeo- 

 cera, Psiloptera, Xenorhipis, Actcnodes, Giyptoscedmorpha, Dystaxia, Schizopus, Mastogenius, Rhaeboscelis, 

 and Taphrocerus have been collected. Xenorhipis has been reared from hickory twigs and Mastogenius 

 from oak twigs, both in the Southern States, but the larvse have not been collected. 



List of Genera, Distribution, Common Habits, and Host Trees. 



Chalcophora. Throughout United States, wood-borer in the stump and trunk of injured, 

 dying, and dead trees: Pine (Pinus), Douglas spruce (Pseudotsuga), and 

 fir (Abies). 



Chalcophorella (Texania). Atlantic States, wood-borer in the stump and trunk of 

 injured, dying, and dead trees: Beech (Fagus), oak (Quercus), and sycamore 

 (Platanus). 



Buprestis. Throughout United States, wood-borer in the stump and trunk of injured, 

 dying, and. dead trees: Pine (Pinus), spruce (Picea), Douglas spruce 

 (Pseudotsuga), fir (Abies), hickory (Hicoria), aspen and cottonwood 

 (Populus), beech (Fagus), chestnut (Castanea), oak (Quercus), and tulip 

 (Liriodendron) . 



Melanophila. Throughout United States, bark-borer in the stump, trunk, top, and 

 branches of healthy, injured, dying, and dead trees: Pine (Pinus), larch 

 (Larix), spruce (Picea), hemlock (Tsuga), Douglas spruce (Pseudotsuga), 

 and fir (Abies). Kills many trees and causes checks or "gum spots" in 

 the wood of others. 



Chrysobothris. Throughout United States, bark and sapwood borer in the roots, stump, 

 trunk, top, and branches of injured, dying, and dead shrubs and trees: 

 Pine (Pinus), spruce (Picea), Douglas spruce (Pseudotsuga), fir (Abies), 

 bald cypress (Taxodium), incense cedar (Libocedrus), cypress (Cupressus), 

 juniper (Juniperus), butternut and walnut (Juglans), hickory (Hicoria), 

 willow (Salix), aspen, poplar, and cottonwood (Populus), birch (Betula), 

 alder (Alnus), beech (Fagus), chestnut (Castanea), oak (Quercus), elm 

 ( Ulmus), hackberry (Celtis), sweet gum (Liquidambar), mountain mahogany 

 (Cercocarpus), apple (Pyrus), Christmas berry (Heteromeles), plum, cherry, 

 and peach (Prunus), catsclaw (Acacia), mesquite (Prosopis), redbud 



