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Three kinds of adelgid spruce galls from Ithaca, NY. July 2012.

#1   Adelges abietis - eastern spruce gall adelgid

Found on Picea abies (Norway spruce)
and Picea glauca (white spruce).
#2   Adelges laricis - "tippy-tip" spruce gall adelgid

Found on Picea abies (Norway spruce).
#3   Adelges cooleyi - Cooley spruce gall adelgid

Only found a few old galls,
on Picea orientalis (Oriental spruce).

Adelges abietis galls (#1) were on the Norway spruces in my parents'
backyard. I never noticed them all these decades despite evidence that they've
been there a long time. There were many old galls, sometimes in large quantities.
#4   An old Adelges abietis gall.
The pegs (needle attachments) sticking out from the stem are still very visible even though the needles have been long gone. All spruces have pegs that protrude from the stem.
#5   Quite a few old Adelges abietis galls.
#6   Many, many, many old Adelges abietis galls.

Adelges abietis (gall #1) nymphs are yellow. See photos below.

I found Adelges abietis on Picea glauca (white spruce) in addition to Picea abies
(Norway spruce). The white spruce galls I found were a little further developed than the Norway
spruce galls; some development chambers had opened up and the adelgids had left. You can see an
empty chamber on the right side of image #7, and three chambers to the left with yellow nymphs.

#7   Adelges abietis gall cut in half.
The chamber on the right was already open,
and the adelgids were gone. The other
three chambers are full of adelgid nymphs.


#8   Close-up of cut-open Adelges abietis gall.

#9   Nymph outside the gall. Note the square shape
of the P. glauca needle and the many rows of stomata.


Adelges laricis (gall #2) nymphs (#10 and #11)   
are dark, not yellow.   

Adelges laricis adults from Picea abies   
(Norway spruce) are all female.   

This species' life cycle includes another generation, on larch (Larix sp.), that results in both males and females. The adelgids eat larch but do not produce galls on larch as they do on Norway spruce.

I only found one tree with these galls, a Norway spruce that was next to 50 other Norway spruces. Only this one tree seemed to have Adelges laricis galls, and no Adelges abietis galls. The neighboring trees had lots of Adelges abietis galls. I'm still wondering why out of 50 or so Norway spruces one, and only one, was galled by a different species of adelgid than all the others. Perhaps that one had a larch growing next to it? I have to go back and look.

#10   Adelges laricis gall cut open.

#11   Close up of Adelges laricis nymphs inside cut-open gall.



Adelges abietis (gall #1) female with eggs (#12).

Adelgid females position their wings in tent-like fashion over their eggs to protect them. Then they die, still protecting their eggs with their body and wings, until the eggs hatch.

Note the square Picea glauca needle with lots of stomata.

#12   Adelges abietis female with eggs.


Adelges laricis (gall #2) adults.
#13   Adelges laricis adult female.

Note the flat Norway spruce needle with fewer
rows of stomata compared with white spruce.

#14   Adelges laricis adult female.
#15   Adelges laricis adult female.


More Adelges laricis (gall #2) adults.
#16   Adelges laricis adult female just emerging.
Wings (yellow) are not expanded yet.
White wool is not there yet either -- it will grow very soon.
Her body color will also shortly darken.
#17   Adelges laricis female with eggs.
#18   Adelges laricis adult.
This one is 2/3 the size of the others and lighter colored once fully matured. I reared a number of these along with the darker, larger adelgids and am not sure what these are. Males? But the males should be on larch. The life cycle of adelgids is complicated and I haven't sorted it all out yet....

Note the pointy tip on the Norway spruce needle -- one of its key characters.



Adelges laricis (gall #2) newly hatched nymph (#19)  
on an old spruce needle.  

#19   Adelges laricis, newly hatched


all photos and text © Joyce Gross