Pest News Update: Lilac/Ash Borer

Inspectors are reporting positive catches of Lilac/ash borer in pheromone traps in Missouri right now! Now is the time to protect your trees with applications of residual insecticides to the main trunk and branches of susceptible species. This insect pest is most often observed infesting ash trees (both green and white) in Missouri, but also attacks lilac, as the common name implies.

LILAC/ASH BORER
Podosesia syringae
Lepidoptera: Sessiidae

Ash borer larva. Photographer: David Cappaert, www.forestryimages.org

DESCRIPTION

• Adult is a clearwing moth, strongly resembling a wasp, about 18-24 mm in length with 24-32 mm wingspan
• The body is brownish black marked with chestnut red
• Larva is a caterpillar, creamy white in color with a brown head, approx. 26-34 mm at maturity

HOSTS

• Fraxinus spp. (Green and White Ash)
• Syringae spp. (Lilac)

DAMAGE

• The larvae bore into the wood of the host plant creating holes in the trunk and main crotch area
• Allow entrance holes for secondary infestations of insects and diseases

LIFE CYCLE

• Overwinters as nearly mature larva in the trunk or cane of the host
• Larva matures and pupates in the spring
• Adults emerge from early to mid April thru June
• Eggs are laid on the bark of the host plants
• Usually one generation per year

INSPECTION TIPS

• Sap mixed with fine frass oozing from small openings in the bark
• Light brown tan colored sawdust like frass
• Later frass extrudes in small clumps evident at entrance hole and at base of the plant
• Males readily attracted to pheromone traps

CONTROL TIPS

• Avoid mechanical injury to plants
• Maintain healthy plants to discourage oviposition
• Monitor adult flight activity with pheromone traps
• Chemical control using labeled pesticides containing permethrin can be applied every 2-3 weeks to trunks and canes when adults begin flying and continued until flight period ends (mid April mid June).

Remember: Before using any chemical, always read the label carefully for directions on application procedures, appropriate rates, first aid, storage, and disposal. Make sure chemical is properly registered for use on the intended pest. Any products named are not intended as endorsements, nor is criticism implied of similar products that are not mentioned. These recommendations are based on observations and conditions in Missouri.

*Control tips for homeowners provided by Chris Starbuck, 573-882-9630. To see MDA recommendations for control in nurseries, visit their Website at www.mda.mo.gov.

Office of the State Entomologist
Missouri Department of Agriculture,
P.O. Box 630, Jefferson City, MO 65102
www.mda.mo.gov