Yellow Poplar Weevils

Identification

• Thanks to their narrow, long-snouted heads and broad bodies, yellow poplar weevils (Odontopus calceatus) are often mistaken for flying ticks. An obvious distinction between the 3/16-inch, black-brown weevils and ticks is that ticks have no wings. They also have eight legs instead of the weevils' six. These differences mean little if you're watching your yellow poplars' leaves being chewed to bits.

Life Cycle

• The adult weevils overwinter in leaf litter beneath their hosts, which also include sassafras (Sassafras albidum) and sweetbay magnolia trees (Magnolia virginiana), which grow in USDA zones 4 and 5 though 9, respectively. Becoming active as the leaf buds swell in spring, they feed on closed buds and expanding leaves. In late spring or early summer, the females deposit from one to 15 eggs in tiny hollows along the leaf backs' midribs. White, C-shaped larvae tunnel from the midribs to the leaves' edges and feed along the margins for three to four weeks before spinning brown cocoons in their mines. After a week, the adults emerge, feed for about a month and drop to the soil to overwinter.

Damage

• Distinguishing adult weevil damage from that of their offspring isn't difficult. Weevil larvae leave telltale brown trails between the leaf midribs and their flat, brown margin feeding areas. The spring-feeding adults make tiny, crescent-shaped leaf holes, while summer-pupated ones chew through the leaves' lower epidermises, or exterior layers, and leave the upper exteriors intact. What you see when they're finished is a tree full of yellow-spotted, scorched-looking foliage. In the worst cases, the leaves brown, wilt and drop.

Control

• As the weevils’ least favorite hosts, yellow poplars seldom see infestations severe enough to need control. The pests prefer to breed on sassafras and feed on magnolias. Control measures for all trees are the same. Applying carbaryl insecticide to kill spring-feeding adults before they lay eggs works on small trees, but those more than 10 feet high require professional spraying. The University of Kentucky recommends spraying only if more than 10 percent of your tree's branches have damage.

  If you can't find a ready-to-use spray, mix your own by adding 4 teaspoons -- or the label's specified amount -- of liquid carbaryl concentrate to 1 gallon of water. Wearing protective clothing and eyewear, thoroughly spray both sides of the leaves with a backpack or compressed-air sprayer. Cover the branches and stems as well. Because the adult weevils move from tree to tree during spring, repeat applications -- no more than once a week -- may be necessary.