Kansas State University


Extension Entomology

Tag: european pine sawfly

2015 Wrap Up: Eastern Tent Caterpillar, European Pine Sawfly, Brownheaded Ash Sawfly

–by Dr. Bob Bauernfeind

I am always amazed at how time flies, especially after having taken a short hiatus. In my last newsletter inclusion (May 1, KIN#4), I referenced the Kentucky Derby. Now here we are already after the Preakness has been run. And American Pharaoh (with two wins under his cinch) is on the verge of the Triple Crown.

But back to KIN #4, when I alluded to eastern tent caterpillars (ETC) and European pine sawflies (EPS) completing their feeding cycles during the week following the Kentucky Derby. That was written prior to the Derby. Actually, the morning of the Derby, I noted both ETC and EPS larvae wandering, having already completed their feeding phases, and in search of sites in which to make their cocoons. Sooooooo, I guess that they both beat the horses across the finish line.

From start to finish: ETC hatch was noted on March 21, and EPS 9 days later (March 30). Fast forwarding to the morning of Saturday (May 2), ETC took 42 days from start-to-finish, and EPS just 33 days. It would appear that the faster EPS might have worn the Roses.

One last early spring entry: brownheaded ash sawflies. As described in the April 24th KIN #3,
I first noted their pinhole feeding. Although but a guesstimate, backtracking, those larvae probably were a week old, making their hatch/“first appearance” on-or-about April 17th. As of Saturday, May 16th, no larvae were to be seen, and newly produced terminal foliage was intact, further indicating that sawfly larvae had completed their feeding cycle. Thus the approximate developmental cycle for brownheaded ash sawflies was 29 days —– much like the rapid development of European pine sawflies.

The Kentucky Derby = Finish Line Winner: ??? Kansas Insect Newsletter???

—Dr. Robert Bauernfeind

Yes —- there is a connection (although admittedly I may streeeetch the rubber band thin). The Kentucky Derby is held the first Saturday of May (tomorrow – May 2) and the winning horse will cross the finish line making some bettors and owners HAPPY!!! Coinciding with this Annual Run-for the-Roses are Eastern tent caterpillars and European pine sawflies which also are fast approaching the finish line for their yearly foraging activities.

Screen Shot 2015-05-02 at 9.51.19 AM

ETCs are nearly mature. I expect that by next week, they will have begun transitioning into their pupal stage. This begins with caterpillars creating their silken cocoons which are coated with a whitish/yellowish powdery substance (which can be irritating to a person’s skin and eyes).

Caterpillars may remain on the host plant, their cocoons being exposed (A) or somewhat concealed/wrapped in a leaf (B). Sometimes caterpillars may go “walkabout”, leaving their tree host to make an individual cocoon, or sometimes gathering and making cocoon clusters (C). After formation of cocoons has been completed, caterpillars transition into their pupal stage (D).

Screen Shot 2015-05-02 at 9.45.13 AM

By late May/early June, moths (A) will emerge and mate. Egg masses will then be deposited on twigs (B). A hard shellac-like coating (C) protects the eggs through the summer heat and rigors of winter. Their cycle will be renewed with egg hatch and caterpillar emergence in March of 2016.

Screen Shot 2015-05-02 at 9.45.12 AM

Regarding EPS, one has but to approach a heavily infested pine to know that the larvae are nearing the end of their feeding stage. The sparse/bare branches (a result of increasingly large larvae satisfying their ravenous appetites) signal an approaching end to their feeding cycle.

Screen Shot 2015-05-02 at 9.45.18 AM

Within a week, larvae will begin forming their thin-walled papery and somewhat leathery cocoons. Like eastern tent caterpillars, some larvae will form cocoons while remaining on their host (A). However, most will leave their host to form cocoons elsewhere. Cocoons may not be obvious because they will be camouflaged with particles of dirt and debris. When cocoons are formed under their host tree, the dirt/debris consists mostly of fecal pellets (B) which dropped to the ground by larvae as they fed.

Screen Shot 2015-05-02 at 9.45.21 AM

Unlike the rather immediate appearance of adults/mating/egg production of eastern tent caterpillars, European pine sawfly larvae aestivate (period of “rest”/decreased metabolic activity in response to higher temperatures) during the summer months. Actual pupation occurs in the fall followed by the emergence of adult sawflies (A) at which time mating occurs and overwintering eggs are inserted into needles (B). Their cycle will be renewed with egg hatch and larval emergence in late March/early April of 2016.

Screen Shot 2015-05-02 at 9.45.26 AM

Eastern Tent Caterpillar (ETC) and European Pine Sawfly (EPS) Update

—by Dr. Bob Bauernfeind

While recent cool temperatures have had people wondering when warmer temperatures will prevail, both ETC and EPS have thrived —– not surprising because these are cool-season insects.

Currently, Eastern Tent Caterpillar “tents” are of sufficient size that they can be easily detected. If people object to the presence of webbing and caterpillars, and if within hands-reach, the easiest remedy is to use your fingers to “rake-out” the web. Preferably do this during daylight hours when most (if not all) caterpillars are “resting” within. Do not fret if several caterpillars fall to the ground —- individually, the few escapees are of no concern. If a person is skittish about touching web masses (and the caterpillars and frass within), that portion of the branch can be pruned and disposed of.

Eastern Tent Caterpillars

European pine sawflies require a different approach because it is impractical to prune out each infested terminal. Fortunately, EPS are highly susceptible to insecticides. There are numerous products registered for use in Kansas against EPS. Horticultural oils and soaps are very effective against the “soft-bodied” larvae. A single thorough application will eliminate EPS larvae. But do so NOW before they become thoroughly destructive.

European pine sawfly