Bark Beetles
FIELD GUIDE TO INSECTS AND DISEASES OF ARIZONA AND NEW MEXICO FORESTS
Cedar and Cypress Bark Beetles
Phloeosinus spp.

Hosts:  Arizona cypress and junipers

Figure 135. Figure 135. Egg galleries of Phloeosinus beetles deeply engrave sapwood and are often thermometer shaped with an enlarged chamber. Conspicuous larval galleries radiate away from both sides of egg galleris.

Symptoms/Signs:  External evidence consists of twig killing (called flagging), or whole trees fading. Under the bark, egg galleries are simple and longitudinal, 2 to 7 cm long, usually engraving the wood rather deeply. Egg niches are usually rather large and conspicuous. Larval galleries wander away from the parent galleries.

Adults are reddish brown to black, shiny beetles ranging in size from 2 to 4 mm long. Larvae are small white grubs, with brown head capsules.

Biology:  One to one and a half generations are produced per year. Attacks occur in spring and summer. Adults and larvae feed in the inner bark in galleries. Newly emerged adults feed on the pith of twigs of living trees prior to constructing egg galleries. Often twigs are hollowed out completely and killed.

Figure 136. Figure 136. Juniper mortality caused by cedar bark beetle near Flagstaff, Arizona.

Effects: These beetles are typically not aggressive and are generally found attacking branches, trunks, tops, and limbs of weakened, dying, or felled trees. Occasionally outbreaks occur during drought.

Similar Insects and Diseases:  This is the main bark beetle genus attacking cypress and juniper. There are some woodboring beetles that attack these trees. Bark beetles are distinguished from woodborers by the shape and location of the galleries and size of the adults and larvae. Galleries of woodborers extend both in the bark and wood. Woodborer larvae and adults are larger than bark beetles.

References:  24, 82

Figure 137. Figure 137. Pitch tubes on Arizona cypress caused by cypress bark beetle near Sedona, Arizona. Note that pitch tubes are frequently absent.
Figure 138. Figure 138. Figure 138. Adult cedar bark beetle (Ploeosinus spp.).
Figure 139. Figure 139. Figure 139. Mortality of Leyland cypress near Sedona, Arizona, caused by cypress bark beetle.
Figure 140. Figure 140. Extensive mortality caused by cypress bark beetle north of Clifton, Arizona.