growth on underside of oak leaf for id if poss

the naturelover · #1 (**permalink**) 09-09-2011, 10:13 PM

HI, I am not sure if this is fungal. Found today on the underside of a falen oak leaf. If you zoom in they appear to be quite hairy. Can anyone id this mass for me please.

regards tn.

Chris Yeates · #2 (**permalink**) 10-09-2011, 12:09 AM

Quote:

Originally Posted by the naturelover

HI, I am not sure if this is fungal. Found today on the underside of a falen oak leaf. If you zoom in they appear to be quite hairy. Can anyone id this mass for me please.

regards tn.

not fungal - it's caused by a Hymenopteran insect called Neuroterus quercusbaccarum - spangle gall; all the gall-wasps which emerge from these will be female

see:
Neuroterus quercusbaccarum - Wikipedia, the free encyclopedia

Chris

the naturelover · #3 (**permalink**) 13-09-2011, 07:01 PM

Chris.
Appologies for the tardy reply been a little bussier than I had expected.
Many thanks for the id and additional information. Very informative.
regards tn.

JAJ · #4 (**permalink**) 14-09-2011, 05:41 PM

Here's an image of the same species of insect or more correctly their impact which causes a reaction in the host tree.

peace J

the naturelover · #5 (**permalink**) 14-09-2011, 06:01 PM

Thanks jaj. You're picture shows spangle gall as i have seen it previously (like polo mints) That is why I was unsure about the id of mine.
regards tn.

poschiavanus · #6 (**permalink**) 14-09-2011, 06:09 PM

Actually this is a different species: the Silk-button Spangle Gall-causer Neuroterus numisalis. There's one other common species of spangle gall-causer Smooth Spangle Gall-causer N. alibipes (picture from Gallery below), and a pretty rare one N. tricolor.

There are several other galls to be spotted on oak leaves around now: round pea galls, big cherry galls, oyster galls, two kinds which turn over part of the leaf edge (Macrodiplopsis spp.).

the naturelover · #7 (**permalink**) 14-09-2011, 06:38 PM

Oh great!
Go on make my life even more difficult then!!just when I thought that I had cracked it!!
Seriously though many thanks for this additional info. I really must stop looking at this tiny stuff

regards tn.

Ladywell · #8 (**permalink**) 14-09-2011, 07:49 PM

Quote: not fungal - it's caused by a Hymenopteran insect called Neuroterus quercusbaccarum - spangle gall; all the gall-wasps which emerge from these will be female

Fascinating - so where do the males come from??

poschiavanus · #9 (**permalink**) 14-09-2011, 08:18 PM

This galls are created by the agamic (parthenogenetic) generation, the agamic females lay eggs in the spring which can turn into males and females. The larvae of these will create another (different) set of galls in the spring sometimes on oak leaves, but often on catkins or buds.

This whole thing works because inheritance of sex in hymenopterans is not via sex chromosomes (like the XY system present in mammals), but via a chromosomal dosage system called haplo-diploidy. One lot of chromosomes and the offspring are male, two and they are female. Note that the wikipedia article does not discuss the case of alternation of generations as seen in the Cynipids. As the agamic generation is all female there is no sperm available from males: I presume the females result from suppression of the second meiotic division, but cant find a reference right now.

You may now understand why Kinsey turned from studying these insects to human sexuality.