garden pest ID

OK, what ARE these pesky critters? I found them earlier this year sucking the life out of some small plants and killed them off. but now they have literally covered every inch of a larch Heliopsis Loraine Sunshine. I tried to spray, but I now I'll never get them all. Should I just cut Loraine down completely to head off the possibility that these bugs will lay eggs if left to long on the plant? 

http://www.flickr.com/photos/kmrsy/2863431106/

HELP!!!

Kitty
neIN, Zone 5 
---------------------------------------------------------------------
To sign-off this list, send email to majordomo@hort.net with the
message text UNSUBSCRIBE GARDENCHAT
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index