2015 Virginia Polytechnic Institute and State University ENTO-169NP

Yellow-poplar weevil Scientific Name: Odontopus calceatus Authors: Hallie Harriman & Tom Kuhar Department of Entomology, Virginia Tech

Other names: Sassafras mining weevil or Magnolia Leaf miner Identification: Yellow-poplar weevils are small black snout beetles and are tick-like in appearance. The adult weevil is about 1/10 inch long and black or dark brown in color. While most weevils are a solid color it has been noted that some southern populations may exhibit yellow antenna, legs, and mouthparts.                Life History: There is one generation of this insect each year. Adults pass the winter months in leaf litter and become active throughout late April and early May. Before leaf buds on Yellow-poplar, Sassafras, or Magnolia trees open, weevils attack the buds and leave their distinctive feeding marks. It is during this feeding frenzy that mating takes place, generally throughout May and early June. The eggs are laid in the midrib on the underside of leaves (Fig. 2). The female does this by puncturing the midrib with her snout and laying 1 to 3 eggs per site. There are generally four or five punctures at each oviposition site, resulting in 12 to 15 eggs per leaf. The eggs hatch in a few days to reveal legless, C-shaped grubs (Fig. 2). Newly hatched larvae move from the midrib into the leaf where they feed as leaf miners for three to four weeks. Once they are ready to pupate, the grubs spin a spherical cocoon in one of the main mining halls they created as larvae (Fig. 2). They remain in these cocoons until the second week of June where they then emerge as adults. The new adults then continue on their journey to eat yet more leaves until mid or late July. From this time onward, they generally disappear into new leaf litter to await the coming spring months.

 

Hosts: Yellow-poplar, Sassafras, Southern magnolia, and Sweetbay magnolia trees

Fig. 1: Yellow poplar weevil adults and feeding injury. Image courtesy of Steven Frank, ecoIPM.org

Fig. 2: Yellow poplar weevil eggs, larvae, and cocoons. All images courtesy of Lacy L. Hyche, Auburn University, Bugwood.org

Distribution: This pest is generally found east of the Mississippi River in all areas where its native hosts exist. It has been noted that its preferred host is Yellow-poplar. Historically, infestations are localized within natural hardwood forests and have rarely been considered a major threat. However, during the 1960’s, several outbreaks caused serious loss of foliage on yellow-poplar populations in the Ohio River Valley and Appalachian Mountain regions. Recent concerns focus on young yellow-poplar transplants that are placed in urban and suburban landscapes. Severe infestations in saplings could damage tree foliage, reduce their ornamental value, and possibly cause low survival rates.

Description of Damage: Adult weevils create brown, rice-sized feeding pits (Fig. 3). They chew through the leaf epidermis, and if prolonged feeding continues can create small holes in the leaves. Large weevil infestations can also cause severe leaf browning (Fig. 4). Weevil larvae are internal miners and will eat the midrib of the leaf as they mature. Mined leaves will eventually break if enough injury occurs. While these weevils do harm foliage they shouldn’t affect the overall health and longevity of established trees. They are often more of a

nuisance than a serious problem and generally only create aesthetic harm.   Control: Most years, natural enemies keep weevil populations in check - pupal parasitoids may destroy more than half of the pupae. Late frosts in the spring also contribute to weevil control by killing both adults and larvae. Nonetheless, there are some years when weevil populations boom. For instance, an outbreak of this weevil was noted in 2015 near Blacksburg, VA. One cultural control suggests that weevils prefer Sassafras and Sweetbay magnolia as a breeding host, and so homeowners should avoiding planting these trees as under story plants if yellow-poplar trees are present. There are also chemical controls available that can be used to eliminate adults and larvae. Insecticides should be applied as soon as the first adult feeding spots are noticed on host leaves. A general rule of thumb is to apply the insecticide when feeding damage accumulates to 10% or more throughout foliage. Resources: Burns, Denver P. “Yellow-Poplar Weevil.” US Forest Service. US Department of Agriculture – Forest Service, 1 Aug. 1971. Web. 3 July 2015. 2015.<http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev2_043569.pdf>.

Fig. 3: Yellow poplar weevil feeding marks. Image courtesy of Lee Townsend, Univ. Kentucky

Fig. 4: Severe leaf injury from yellow poplar weevil. Image courtesy of Lacy L. Hyche, Auburn University, Bugwood.org

Frank, Steven. “Yellow Poplar Weevil.” Entomology Insect Biology and Management News. NC Cooperative Extension, 1 June 2015. Web. 3 July 2015. 2015.<http://entomologyces.ncsu.edu/2015/06/yellow-poplar-weevils/>. Hyche, L.L. “Auburn University Entomology and Plant Pathology | Yellow-Poplar Leaf-Mining Weevil.” Auburn University Entomology and Plant Pathology. Auburn University - College of Agriculture, 1 July 1994. Web. 3 July 2015. <http://enpp.auburn.edu/outreach/web-publications/yellow-poplar-leaf-mining-weevil/>. Townsend, Lee. “Yellow Poplar Weevil.” Kentucky Pest News. UK Agriculture Extension, 23 June 2015. Web. 3 July 2015. <http://kentuckypestnews.wordpress.com/2015/06/23/yellow-poplar-weevil/>. Townsend, Lee. “YELLOW POPLAR WEEVIL.” UK Entomology. University of Kentucky, 22 Jan. 2013. Web. 3 July 2015. <http://www2.ca.uky.edu/entomology/entfacts/ef414.asp>. “Yellow Poplar Weevil BUG DOC FactSheets.” Ornamental BUG DOC FactSheets. The Ohio State University. Web. 3 July 2015. <http://entomology.osu.edu/bugdoc/Shetlar/factsheet/ornamental/FSyellowpopweevil.htm>.