2004 Season Review: Insect Problems on Ornamentals

Cliff Sadof, Professor, Entomology, Purdue University

The rainy cool summer brought much pleasant weather, and dampened the spirits of our most hearty insect pests.  Japanese beetle populations, like last year were very much diminished in most of the state. Hot weather associated with adult flight simply failed to occur.  Wet weather this year assured a healthy grub population for this fall.

This year saw our first public concerns about gypsy moth activity in the northeastern part of the states. It ran the whole gamut, from a failed court injunction to stop BT applications, to the public wanting their neighborhoods treated for gypsy moth. Fortunately the gypsy moth population took a nose dive with annual trap catch reduced to about 12,000 moths, or about half of what we had last year.  

Outbreaks of half wing geometers and linden looper were found in south central Indiana in Jackson, Washington, Floyd, Perry, Harrison, Crawford and Clark counties this spring. Further to the east toward Madison, an outbreak of forest tent caterpillar defoliated ridge tops along the Ohio River.  More red elms (Ulmus rubrum) continue to enter an age class that is more susceptible to outbreaks of Dutch elm disease. Heavy rains over the 4th of July weekend dumped over 10" of rain along the Wabash Valley causing a 50-year flood event in North Central Indiana.  Another 10" of rain fell on Labor Day weekend in Indianapolis causing more record flood events. 

August also brought about another outbreak year of fall webworms.  The outbreak seems to have spread from the north to as far south as Evansville.  Bagworms and mimosa webworms were abundant as well. Despite the cold wet weather, there were numerous outbreaks of spider mites on maples and oaks. Some curiosities- for the second year in a row, a flea weevil (apple flea weevil) Rhynchaenus pallicornis (Say) was seen to defoliate local elms.  With one generation a year, this early season leaf miner and late season adult defoliator seems to have replaced Elm leaf beetle as our local principle defoliator of elms.  Beech blight aphid, Grylloprociphilus imbricator, has caused numerous phone calls this fall, but does not appear to be causing much damage.  Asian ambrosia beetles continue to be reported in few nurseries in southern Indiana. They have not yet emerged as a landscape pest.