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Wednesday, 14 May 2008

Flight path

Charlie F, Berkeley, California, US


I have yellow jackets that hang around my roses and crawl around the leaves. I used to put traps up because you couldn't even eat a sandwich outside without them bothering you. They are meat eaters and seem to be especially attracted to mandarin chicken. One day I got up close to see what they were so interested in on the roses and I noticed that every once in a while they would find a small green worm and fly away with it. This explained why my roses were decimated when I put the hornet traps up. Now I leave them alone and my roses are fine.
By Anonymous Anonymous on October 10, 2007 7:28 PM  
The insect pictured is actually a wasp and there could be a good reason that they're there.

''Seems like you have an infestation of a wooley bug. They secrete a very sweet substance that attracts wasps and butterflies. You will be able to tell because you will see what appears to be sooty streaks where they are, and they huddle together.'' - a quote from Tucksie on Yahoo answers about a similar question.
By Anonymous Anonymous on October 10, 2007 8:56 PM  
I'm no entomologist but that's a wasp or a hornet (too low res) not a bee. As it's a wasp and not a bee I'd suspect that they're eating some other bug on the leaves.
As the others have stated the "bee" in question seems to be a Yellow Jacket.

Yellow Jackets feed primarily on insects in spring and early summer, then switch to a more omnivorous diet in late summer and fall, being especially attracted to fruits and anything containing sugar.

So depending on the time of year they may be finding small insects on the leaves as someone has already stated or eating sugary tree sap from the leaf surface.

They also chew up bark and wood to make their "paper" nests.
By Anonymous Anonymous on October 18, 2007 11:30 PM  
The Tree is a Liriodendron tulipefera, or tuliptree. They are a favorite host for many types of aphid( a sure sign is a sooty wet deposit all over the leaves...aphid poop!). Aphids are in turn an easy snack for any carnivorous bug passing by. Check closer you will likely find ants tending them as well as lacewings and other creatures feeding on them.

P.S. dont park your car under this tree, it or anything else will get all gooey!
By Anonymous Anonymous on October 30, 2007 3:56 PM  
The following answer has been selected and edited by New Scientist staff

The insect pictured appears to be a social wasp (or yellow jacket as it is known in the US) rather than a bee. The foliage the wasp is sitting on is that of the tulip tree, Liriodendron tulipifera.

I suspect this particular tree is infested with a pale green aphid, Illinoia liriodendri, which is a common pest on that plant. Heavy infestations build up during the summer and the foliage becomes increasingly sticky as a fine drizzle of sugary honeydew, excreted by the aphids, accumulates on it. Honeydew is eaten by a wide range of insects, including wasps, flies and sometimes bees. The wasps you saw will have been tucking into the honeydew.

The tulip-tree aphid is a North American species that has recently become established in the UK. Since it was first found here in 2004 in the London area, it has turned up in a number of places in southern England and south Wales.

Andrew Halstead, Principal Entomologist, Royal Horticultural Society, Wisley, Surrey, UK
The following answer has been selected and edited by New Scientist staff

This photograph is of a wasp, not a bee. The most likely explanation is that the wasps are attracted by honeydew, though it is conceivable that they also come to drink droplets of water on the leaves.

Wasps are normally carnivorous, but in the autumn the colonies break up and the nests are abandoned, leaving the wasps to fend for themselves. It is at this time especially that they are attracted by sugary liquids, such as those found in fruit, jam and honeydew.

Honeydew is excreted by aphids and plant hoppers whose piercing mouthparts enable them to feed on sap from the leaves. The sap is rich in sugars but poor in protein. What protein it does contain is extracted by the insect's gut, but most of the rest of the sap is excreted, coating the leaves on which the insects feed with honeydew.

Some ant species actually farm aphids for their honeydew, collecting and carrying the aphids to suitable plants. When stimulated, the aphids excrete a droplet of honeydew which the ants feed on. The relationship is mutually beneficial: in return, the ants keep any aphid predators at bay.

Terence Hollingworth, Blagnac, France
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