The adults of the Phoenix and hunting billbugs are dark brown and light brown, respectively. Both are weevils (snout beetles) 0.33 inches long with a long, downward-pointing snout and elbowed, clubbed antennae. In California, the Phoenix billbug outnumbers the hunting billbug. A Y-shaped pattern on the thorax with distinct, inward-facing markings that resemble parentheses on either side of the Y distinguishes the hunting billbug.
The Phoenix billbug’s two markings combine to create an M. Adults are frequently observed wandering on paved surfaces but are difficult to locate on golf courses unless a drench test is employed.
Turfgrass stems are injected with eggs. They hatch 6 to 8 weeks after the adults appear.
Larvae are cream-colored, legless, hunch-backed C-shaped grubs with a brown head. Billbug grubs are distinguished from white grubs by the absence of legs.
Host plant:
Cool-season turf (Kentucky bluegrass, ryegrass, fescues, bentgrass) can provide patchy brown turf that converges to bigger areas of warm-season turf (zoysiagrass, St. Augustinegrass).
Territory:
It is found in North America.
Damages caused by Phoenix Billbug:
Billbug larvae feed on the interior of the turfgrass stem and crown before moving into the soil to feed on roots. Fine, yellowish, sawdustlike larvae feces (frass) may be seen on the soil surface. Because billbug larvae eat higher up on the roots than white grubs, billbug-damaged turf is simpler to extract from the soil than white grub-damaged grass, which breaks at the crown. Billbugs may feed on roots up to 3 inches deep; however, unlike white grub-damaged turf, damaged turf cannot be dragged back like a carpet, and the soil does not feel spongy underfoot. Turfgrass grown on fumigated soil is particularly vulnerable to injury due to the absence of natural enemies. Drought-stressed turfgrass may suffer greatly.
Life history and habits:
Eggs are placed in tiny clutches towards the crowns of plants on the bases of grass stems. They are seldom observed.The minute larvae hatch in approximately 2 weeks and graze briefly within the grass stems before burrowing down to feed on the crowns. Later, they travel to the soil’s root zone and feed on roots and rhizomes. Larvae are often numerous from mid-July to mid-August. Æ In late summer, larvae pupate in little chambers they construct in the soil near diseased grassroots, emerging as adults after a few weeks. New adults are most common in late September and early October when they can be seen in large numbers on driveways and sidewalks. Adult billbugs may nibble on grass blades or carve notches in the margins, although this stage normally causes little turf damage. Adults spend the winter on contaminated turf or in neighboring protected locations. Adults become immobile when disturbed, making them difficult to locate while scouting in grass plots. Most billbug species in New Mexico have one generation per year, with a partial second generation occurring in some warmer locations.
