space badger's picture

Unidentified black insect eggs/cases

Observed: 4th September 2011 By: space badger
Black shiny insect eggs cluster
Black shiny insect eggs cluster 1

These shiny, black, slightly oblong items are not much bigger than elderberries. They are clustered around the nail head on which a ceramic decorative birdhouse is sitting. The tree the birdhouse is attached to is a cherry.
Apologies for the lack of picture quality - I am short, the birdhouse is high.

    Likely ID
    Tree Sap
    Confidence: I'm as sure as I can be.
  • Shield bug egg cases
    Confidence: It's likely to be this, but I can't be certain.
Species interactions

No interactions present.


space badger's picture

I would love an identification

Thank you in advance for any help anyone can give in pointing me to an identification. Mostly because I'm nosy and like to know what's living in my garden, but also now because I've asked the odd ecologist and insect fancier I know, and they haven't been able to tell me. At work, it's considered a proper mystery, and I'm now not the only one interested in finding out.

Refugee's picture


The clue is the fact that cherry trees bleed a resin when they are injured and this has gone into the bird box through the fixing hole.
It is a response to the nail hole in the tree.


space badger's picture

Not sure about sap.

Thank you, Refugee. I'm not convinced, though. I've looked at the sap theory, but ruled it out for the following reasons...
this is not a new nail, but an existing one I hung the birdhouse on because I'm lazy and it was already there (for years, I believe).I suppose it could have started spontaneously bleeding this year, though (?)

Also, the tree has sustained slight damage elsewhere; in that place, and on surrounding cherries, the sap is a light honey brown colour, which has a consistency that tends to ooze like a spill rather than beading.

If you look at the picture, the items in question are very neat and self-contained as well as uniform, no drips, no dribbles, no ooze. And I can confirm they are black (and shiny, so not just mucky) rather than brown, all of which seemed to me to argue against sap.

If you can convince me it's sap despite the above, that's great, as I've had no other suggestions.

Refugee's picture


What is the back of the nest box made of? It looks grey and not the same material as the front. If the nail has been nudged it is likely to have re-started the bleeding and if it is old also stain the resin.
Just lift it down and have a look at the nail closely to see if there is any fresh bleeding. The box will be hotter than the open wood and that should make it dry out more quickly.


space badger's picture

The birdhouse is ceramic.

The birdhouse is ceramic. I'll see if I can have a look at it today. Thanks.

space badger's picture

New identification

I had a friend send these photos and a description to an entomologist he knows. While unable to tell me the exact kind of shield bug he felt this was produced by, that was the identification he gave.

It's an ID I'm more comfortable with than tree sap - probably because I've seen the actual thing, and I'm 99.9% sure it isn't sap.

Refugee's picture

They are white

I have seen a picture of shield bug eggs hatching and they were white and the young hatched out with there first moult markings. They would show through clear egg cases.
Try removing one and have a good look at it maybe cut it open.


space badger's picture

There seem to be a variety of colours

There seem to be a variety of colours of shield bug egg, as yes, the egg cases do appear to be transparent.
I will have to go back and see what, if anything, has happened recently to my little guests, and report back.
I think I can safely say they're not alien spider eggs from Mars, as some friends have suggested ;0)

DavidNotton's picture

not shield bug eggs

These are usually almost spherical, and laid in regular clumps