Ask the Steward

By Dan Ernst


Question: What affect will this past year’s Polar Vortex have on the survival of Emerald Ash Borer?

Answer: This past winter was surely one for the record books!  The deep double digit freeze was widespread and reached 17 below zero on my back porch and a few degrees colder in some areas of the state.  Some have speculated that surely the prolonged deep freeze will put the hurt on the critters.  The actual impact will not be clear until early summer when beetles emerge from beneath the tree’s bark.  During winter months EAB are present as larvae under the bark of Ash.  This bark protects them from predators and the elements.  Add to this the larvae unique approach to surviving the cold.  To insure survival, they purge all stomach contents that could freeze- and actually fold themselves in half doing this.  Even with this adaptation some of the larvae will not survive the winter.  Some studies have indicated as much as 33% mortality at negative 10 degrees, and 50% at negative 20 degrees.  However, there is also some prevailing thought that this may be best case scenario and actual loss may be less, with tree by tree variability a near certainty.   The length of freeze may also have had an impact and combined with the frigid temp will likely set back EAB populations for a couple years.  This short reprieve will give tree owners and landowners some additional time to evaluate their trees, and undertake management and treatment options. For more information on EAB and control measures visit:

Question: Are there really Rain Crows in Indiana?

Answer: Yes there are!  The “Rain Crow” is one of the last migrating birds to return to Indiana.   Its’ common name is the Yellow-Billed Cuckoo and is also known as “Storm Crow”.  The colloquial name comes from the tendency for the bird to belt out its’ distinctive and drawn out knocking call in response to loud noises- often before summer rains in response to thunder. Well adapted to its’ late arrival, the Yellow-Billed Cuckoo has one of the shortest nesting cycles of any bird- a mere 17days from incubation to fledging.  While hatching nearly featherless they are fully feathered and ready to leave the nest within a week.  It is one of the few birds able to eat large numbers of hairy caterpillars- like Gypsy moth larvae and tent caterpillars.  Reportedly eating as many as 100 in a single feeding.  They’ll also load up during cicada outbreaks.  That is good news to farmers and forest owners.  Population of the species is in decline, especially in Western states, primarily

due to urban development and habitat loss. Preferred habitats are woodlands  and shrublands with dense stands of young trees areas, thickets and water sources nearby.

Dan Ernst is an Assistant State Forester with the Indiana Division of Forestry. He oversees the state forests in Indiana and has authored the “Ask the Steward” column for years. Have a question for the column? Email Dan at