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Hackberry galls - Pachypsylla celtidismamma

Hackberry galls - Pachypsylla celtidismamma
Toronto, Ontario, Canada
September 19, 2008
Size: galls 4 - 8mm wide
It took me a little while to figure out the host tree - Celtis occidentalis - but after that, identiying the gall-makers was quite simple. I think this is probably species P. celtidismamma (Hackberry nipple gall), but would welcome a second opinion. Posting at genus level for now.

Images of this individual: tag all
Hackberry galls - Pachypsylla celtidismamma Hackberry galls - Pachypsylla celtidismamma Hackberry galls - Pachypsylla celtidismamma Hackberry gall psyllid nymphs - Pachypsylla celtidismamma Hackberry gall psyllid nymph - Pachypsylla celtidismamma Hackberry gall psyllid nymph - Pachypsylla celtidismamma Hackberry gall psyllid adult - Pachypsylla celtidismamma Hackberry gall psyllid adult - Pachypsylla celtidismamma Hackberry galls - Pachypsylla celtidismamma

Two species here, actually
Hi Hannah - what you've got here is actually more interesting than you may have realized. All of the galls are indeed P. celtidismamma, though all of the nymphs are not. Specifically, in this photo

the two nymphs on the bottom are P. celtidismamma, while the nymph at the top is P. cohabitans, an inquiline non-gall forming species.

You mentioned that each gall you opened contained multiple nymphs. The gall itself is induced by the nymphs of P. celtidismamma; P. cohabitans nymphs settle near P. celtidismamma nymphs during gall initiation and become incorporated into the gall, resulting in galls with additional cells. P. celtidismamma may be found in the center cell, while the inquiline species may be found in side cells. Note that P. cohabitans may incorporate itself into the galls of all other leaf-galling Pachypsylla spp. as well.

Morphologically, the inquiline species is extremely similar to the gall-forming species. In adults, the only way to distinguish between them is the abdomen color (in females) and the shape of the paramere (in males). Because both of these things are usually hidden behind opaque wings, adults of the inquiline often become impossible to ID from photos, and are usually assumed to be the gall-forming species. This results in the inquiline being under-represented in images, including here on BugGuide. The inquiline, however, is not uncommon, and occurs widely throughout the range of the gall-forming Pachypsylla.

Fortunately, the nymphs have a much more convenient visible 'tell' that allows them to be easily separated from the gall-forming species, and that is in the color of the wingpads. In late instar P. celtidismamma, the wing pads are brown, while in P. cohabitans the wing pads are yellow. Because of this and your statement regarding multiple nymphs per gall, I am calling the yellow-wingpad nymph in the linked image P. cohabitans.

I realize that these photos were taken over 8 years ago, but if you happen to have any closer cropped photos of that nymph or photos of other nymphs with yellow wing pads, they would be a valuable contribution.

Further reading: Yang, Mitter, & Miller (2001) First incidence of inquilinism in gall-forming psyllids, with a description of the new inquiline species

I suspect I posted all my best shots
but when I get a chance (after Christmas) I'll look through my old files in case there is something better. What an amazing life cycle P. cohabitans has! Thanks for explaining it!

Pachypsylla celtidismamma
In an effort to sort out the confusing mess of hackberry psyllid galls, I've shown a bunch of BugGuide photos to John Moser, who researches hackberry gallmakers and arthropod associates. For the record, he agreed with the ID for this series ("These appear to be small P. celtidismamma.").

Cranshaw is a great reference, but I've found several errors, so it's nice to have another opinion on these.

Moved from Hackberry Psyllids.

great set of pics -- thanks!
galls look exactly like P. celtidismamma's in Whitney Cranshaw's Garden Insects of N.America

Great reference - thanks!
Not only info and images of this species but also helps rule out other spp. that also host on hackberry. I will create a guide page for this species.

Thanks, v
I actually own that book, and will look it up this evening.

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