Given the time of the year, caseload at the UW Insect Diagnostic Lab (IDL) is currently low but is expected to increase over the next month.  A summary of recent fruit crop insects reported to the UW Insect Diagnostic Lab as well as important insects to scout for can be found below:

Scale insects: Recently, I’ve seen a few samples of oystershell scales and San Jose scales from orchard settings at the IDL.  The winter and early spring months can be a good time to scout for scale insects as it’s easier to check twigs and branches due to the lack of foliage.  Some scale insects can also be managed early in the season with dormant oil treatments.  Knowing the exact scale species can be extremely helpful to narrow down the time window to target juveniles (“crawlers”) later in the growing season.

Eastern tent caterpillar: I have not received any reports of caterpillar activity yet, and it’ll probably be a few weeks before they start becoming active.  However, winter and early spring can be good times scout for egg masses.  Egg masses can contain several hundred eggs and are covered with a dark varnish-like coating; they typically are located towards tips of branches and often encircle small diameter twigs (≤ ¼ inch diameter).  Removal of egg masses via pruning can be a consideration as well as dormant oil treatments.  Finding lots of egg masses could give growers a head’s up for scouting purposes later this spring. 

Spongy moth: The spongy moth (Lymantria dispar) was formerly known as the “gypsy moth” but underwent a name change earlier this year.  Spongy moth populations trended upwards in many parts of the state in 2021 due to dry conditions, so growers should have this pest on their radar for the spring months.  Spongy moth caterpillars will likely become active in southern parts of Wisconsin in the next 3-4 weeks.  In the meantime, growers can scout for the egg masses—each containing upwards of 1,000 eggs.  Egg masses are beige and velvety, with a spongy consistency and are often 1-2 inches long.  Management options for egg masses include removal (scraping off with a putty knife) or treatment with dormant oils.  While often on tree trunks or branches, egg masses can be on other items including sides of buildings, piles of firewood, vehicles/equipment, pallets/crates, etc.

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Reminder about diagnostic support from the IDL: A quick reminder that growers and consultants in need of insect diagnostic services are always welcome to submit a sample to the UW Insect Diagnostic Lab.  Lab services are provided free of charge.  You can find additional information about the IDL here: insectlab.russell.wisc.edu.

This article was posted in Insects and tagged eastern tent caterpillar, Insect Diagnostic Lab, insects, PJ Liesch, scale insects, spongy moth.