Conifer tree insects

[Dinasaw]

At last I have uploaded photos, I think, of the insects that have invaded a tree in my garden. They measure about 5mm long, excluding legs and 3mm across. Huge!
What are they please? Any info welcomed, including common name, where they have come from, what they are doing and if they are harmful!!!
Many thanks!

[Paul mabbott]

They're aphids (Hemiptera: Homoptera), wouldn't like to guess at the species/genus but members of the Adelgidae are common on conifers - like these in your picture (I think) they have no cornicles. Knowing what genus the tree is might be helpful.

[Dinasaw]

Well, thank you! I guessed they were aphids, by their shape and their attraction for wasps, but they are bigger than any I've seen before. I don't know the kind of tree, as it was planted before we came here, but I am supposing it to be a replanted ex-Christmas tree, so, possibly a Norway Spruce? It has, by the way, an attractive crop of deep pinky-red cones this spring. So, please tell me how the aphids have arrived on the tree - have they emerged from underground or what? Yep, I don't know much!

[Paul mabbott]

Firstly, we have people on board who know a lot more about aphids than I do so sit around and you may get better advice!
Movement of aphids depends rather on the species! Most of them have many generations per year. Many species have overwintering winged (alate) forms which stay in sheltered places with a little food supply in the winter; in the spring they fly off to places with better food supplies i.e. plants starting to produce fresh greenery. Subsequent generations are wingless (apterous) until the food dries up.
However, life cycles are very, very variable ...... some, as you suggest, overwinter underground, others form waxy 'nests'.
Hope that helps - it's about the limit of my knowledge without reading up!

Originally Posted by Dinasaw

Well, thank you! I guessed they were aphids, by their shape and their attraction for wasps, but they are bigger than any I've seen before. I don't know the kind of tree, as it was planted before we came here, but I am supposing it to be a replanted ex-Christmas tree, so, possibly a Norway Spruce? It has, by the way, an attractive crop of deep pinky-red cones this spring. So, please tell me how the aphids have arrived on the tree - have they emerged from underground or what? Yep, I don't know much!

[Dinasaw]

Eeek!! Aphid alert! Well, I think these are indeed emerging from the earth, as there is now a seething mass of them at the base of the trunk of the tree. They seem to be all sizes - would they be male and female, or are they younger and more mature? Yes, they are making my hair stand up, so I'm not going any closer to investigate or photograph - but am hoping some bird will find them tasty! Just now, I am feeling the tree is much too close to the house...!!!
Any more info, for the layman, would be welcome.