Agri-Life Minute: New Threat to Your Oak Trees – The Yellow Necked Caterpillar [VIDEO]

There’s a new insect that has emerged on to the scene this summer that is causing a great deal of concern for folks that have Live Oak Trees, it is the Yellow Necked Caterpillar (Dantana ministra).  These little devils are showing up mainly on Live Oaks this season in record numbers.  The Adults are of course a moth that flies from June through August, laying eggs in trees.  The Larvae (caterpillar) begins showing up sometime in late May and can be present from then until October.

Caterpillars are predominately black with a red last segment and yellow lengthwise stripes.  Their head and legs are bright red and a mature caterpillar is about 2″ long.  Larvae feed mainly on leaves of live oaks in the South Central Texas region, skeletonizing leaves or devouring entire leaves.  If enough of them are present on a tree they can defoliate much of plant before detection.  Caterpillars are known to hang by silken threads, and are seldom a widespread pest on oaks, but heavily infested trees may be defoliated completely by mid to late summer.

There are several natural enemies that attack this pest. Birds such as robins feed on larvae. Predaceous bugs and parasitic flies may also attack this species. Monitor trees from mid-June through July for signs of this pest. Where possible remove foliage that contain white masses of eggs on the lower surface. If necessary, apply a registered formulation of an insecticide when larvae are small.

Treatment of these insects can be tricky, due to the fact that most infestations begin at the top of the tree and work down, so it is difficult to get chemical that high into the tree.  Ideally it is best to treat with an insecticide when caterpillars are first noticed.  Some of the most available and recommended insecticides include carbaryl (Sevin 50 WP) and cyfluthrin, sold commonly as Bayer Advanced Garden and Multi-Insect Killer.

For more information on the control of this pest, contact the Texas A&M AgriLife Extension Service at (979) 865-2072, or visit our website at http://austin.agrilife.org and click on the Ask the Agent tab.