As we have discussed in the past, the little adult psyllids that emerge from
the nipplegalls on hackberry leaves overwinter in the bark of hackberry and
nearby trees (especially spruce). In spring they come out of their bark hiding
places, mate, and the female adults lay eggs on swelling hackberry buds. The
resultant nymphs tunnel into the needle and cause the formation of the next
crop of leaf galls.
On February 19 (last Friday) in Fort Collins' Grandview Cemetery (Larimer) a
couple visiting birders and I noticed some bird species known to be psyllid
gleaners (Brown Creepers, Mountain Chickadee, Golden-crowned Kinglets, and
Ruby-crowned Kinglets) acting a little differently than they have been all
winter. During cold days over the last 3 months or so, psyllid-seeking birds
they usually confine their hunting to the interior of tree crowns, especially
up high. The other day they were at the base of the trunk of a
chronically-infested hackberry and on the ground under that same tree. The
tree where we saw this is the one that had the Cape May Warbler in late fall
2014, for those of you who saw that special psyllid-eating bird. I checked a
few polished stone grave markers nearby (where adult psyllids are easier to see
than on bark) and, sure enough, saw a few adult psyllids out and about. This
seems very early, but given the warm temperatures we've been having, maybe not
all that surprising. These insects are laden with anti-freeze chemicals and
will probably survive the next cold snap by simply going back into their bark
niches.
At any rate, the lower trunks of hackberries might be worth checking for
gleaners, at least until the weather gets cold again.
Dave Leatherman
Fort Collins
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