Imported Willow Leaf Beetle

Subject: Willow eating bug
Location: Eastern Pennsylvania, USA
June 3, 2014 4:49 am
Our willow tree leaves are being eaten away by this strange creature. Please help identify it.
Signature: David

these are predatory lady beetle larvae and they feed on aphids, not leaves.

Ah! So the aphids should be somewhere about eating the leaves then?

no, aphids suck the juices from plants

I’ll try again…this little thing is definitely eating the leaves on my Willow tree.

Leaf Beetle Larva
Leaf Beetle Larva

Bingo David,
This is the larva of a Leaf Beetle in the family Chrysomelidae, and we will attempt to identify it to the species level for you.  Willow is a popular food plant among insects, including species of butterfly caterpillars, moth caterpillars and aphids
.  We seem to recall a Willow Leaf Beetle identification in the past and we were correct, however, the larva pictured on BugGuide looks nothing like your Leaf Beetle Larva.  We believe we found a larva that matches yours identified on the Evolution in Structured Populations University of Vermont website, but the are only identified generally and this behavior is described:  “Imported willow leaf beetles are group foragers.  Larger groups survive better than small groups.”  The University of Minnesota Extension website identifies the Imported Willow Leaf Beetle as Plagiodera versicolora and states: “Adult beetles make notches or holes in leaves/  Larvae windowpane leaves, i.e. they feed on the upper surface of the leaves between the veins.  Prefers willows and poplars, especially weeping willow.  Adults are bluish-black to greenish blue, about ⅛ – ¼ inch long.  Larvae are dark, almost black and about ¼ inch long.”  According to BugGuide, you are in the range of the Imported Willow Leaf Beetle. 

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