Species of the Month - December 2014

Giant Willow Aphid

Tuberolachnus salignus


Said by some to be the world's largest aphid, the Giant (or Large) Willow Aphid is also one of the least understood.  It's an enigmatic creature that breaks all the rules.  Normally a rare beast, with only 4 dots on the NBN map of Britain, it is having a bumper year with sightings reported from many parts of northern Scotland.


Tuberolachnus salignus

The aphid is found in large aggregations on willow branches.  It prefers branches of about 1-3 cm diameter, that are old but not covered with moss or lichen.  Groups of aphids can be seen from a distance as dark patches on the underside of branches.

When you find a willow, scan it for dark patches, and if you find any check that they are made up of aphids and not caused by something else.  The aphids are unmistakable.  The adults are up to 5 or 6 mm long and have a tubercle on their back like a shark's fin.  Aphids of all ages and sizes will be present, since they reproduce continually through the winter.  The younger ones do not have the tubercle, but they are still distinctive with the rows of black spots on a grey background.  Nothing else that is at all similar forms patches on willow in winter.
 

Tuberolachnus salignus   Tuberolachnus salignus

No male Giant Willow Aphid has ever been found.  The colonies are made up of females who give birth to live young who are genetically clones of their mother.  Some adult females grow wings, but most do not.
 

Tuberolachnus salignus

This picture shows the "shark's fin" on the back of an adult aphid.  This is easily seen if you view them from the side.  No other species of aphid has this feature, and its purpose is not known.

Unlike just about every other insect, the Giant Willow Aphid is most active during freezing weather, when they may leave the trees and walk about in a fast and purposeful manner.  In the summer, by contrast, they completely disappear.  No-one knows where they go between March and August.  Perhaps this year, when they are so much more plentiful than usual, someone will find out.

Here are some links to articles about this fascinating creature.  They are well worth reading.

The photos on this page are taken from the Influential Points site under a Creative Commons Attribution 3.0 Unported License, as I don't yet have any decent photos taken by me or other LNHG members.  So the next challenge after finding the aphids is to take some really good macro shots of them and also more distant shots showing the dark patches on the trees.  Then we can replace these photos with our own.


Please send in your Giant Willow Aphid sightings using the form below, or email sightings@lnhg.org.uk with the details if you prefer.  If you are not sure of the identity of your aphid, please send a photo to sightings@lnhg.org.uk, or put one on the LORN forum and let me know it is there.
 

Date of sighting 
Host tree if known (use fallen leaves to identify!)  
Location 
Grid reference 
Name of finder 
Your name (if different) 
Email (not needed if I already know it!) 
Any other details, e.g habitat, behaviour,
 number of aphid clusters,
number of trees affected
   


 

By filling in this form you agree that the information contained in this form may be collated and disseminated manually or electronically for environmental decision-making, education, research and other public benefit uses in accordance with the LNHG data access policy.  Your email address will not form part of the record and will not be passed on to anyone.

Carl Farmer
LNHG Biological Records Manager


Sightings so far

25 Nov: Colonies on 2 Grey Willows (Salix cinerea) on LNHG field trip at Polanach, N of Appin

29 Nov: One small colony on Eared Willow (Salix aurita) found by me at Ganavan

 


Note you can still send in records for past species of the month.  Here is the list of species we've had so far:

Nov 2014 - Golden Spindles
Oct 2014 - Crimson Waxcap
Sep 2014 - Four-spotted Orb Weaver
Aug 2014 - Pale Butterwort
Jul 2014 - Melancholy Thistle
Jun 2014 - Forester Moth
May 2014 - Large Red Damselfly

Apr 2014 - Hedgehog
Mar 2014 - Hairy Bittercress
Feb 2014 - Pale Brindled Beauty
Jan 2014 - Velvet Shank
Dec 2013 - Frilly-fruited Jelly Lichen
Nov 2013 - Whooper Swan
Oct 2013 - Ballerina Waxcap
Sep 2013 - Parrot Waxcap
Aug 2013 - Vapourer Moth

Jul 2013 - Emerald Damselfly
Jun 2013 - Globe Flower
May 2013 - Early Purple Orchid
Apr 2013 - Peacock Butterfly
Mar 2013 - Oak Beauty
Feb 2013 - Coral Lungwort

Jan 2013 - Willow Jelly Button & Birch Jelly Button
Dec 2012 - Dice Lichen
Nov 2012 - Feathered Thorn
Oct 2012 - Dryad's Saddle
Sep 2012 - Tawny Grisette
Aug 2012 - Forest Bug
Jul 2012 - Grayling
Jun 2012 - Greater and Lesser Butterfly Orchids
May 2012 - Small Copper
Apr 2012 - Green Tiger Beetle
Mar 2012 - March Moth
Feb 2012 - Barren Strawberry
Jan 2012 - Brambling
Dec 2011 - Red Squirrel
Nov 2011 - Hazel Gloves
Oct 2011 - Small Tortoiseshell
Sep 2011 - Fly Agaric
Aug 2011 - Grass of Parnassus
Jul 2011 - Golden-ringed Dragonfly
Jun 2011 - 7-spot Ladybird
May 2011 - Green Hairstreak
Apr 2011 - Townhall Clock

Mar 2011 - Frogspawn

Next month's page
Current month's page


This project is supported by Scottish Natural Heritage



Text copyright Carl Farmer.  Photos Creative Commons Attribution 3.0 Unported License, credit an
d link to InfluentialPoints.com