Sunday, July 15, 2018

Rose Gall - Diplolepis rosae

Watering my garden this morning, I noticed yellowing leaves on my Rosa glauca. A sign of heat stress. Yet, as I looked closer, I saw a mossy mass which I've only ever seen once before.

I knew this is a rose gall, but I wasn't sure what was causing this gall.  Galls can 'grow' on all sorts of plants. Sometimes it's a sign that the plant is stressed.

I took my secateurs and cut the gall off with two sets of leaves at the base of the gall.

Mossy hard mass. Really cool.

Took my secateurs and cut the gall in half. Found several larvae in sections. Each within their own chamber.

They are in fact larvae from a wasp.

Non-native - an European introduction called: Diplolepis rosae.

The most fascinating aspect is: how the heck did they get in there?

Adult wasps lay eggs on the plant and once a larva hatches, it begins to feed on leaf bud tissue, and an amazing process begins. The host plant is stimulated somehow with the feeding, where cells from the surrounding tissue multiply, adding layers of tissue - forming this gall. The larvae within, creates a microhabitat, where not only they are protected and housed, but the chambers they indwell also become their food source.  A hotel with room service, if you will.

Pretty cool.

However, since it's an non-native intruder, I squished the gall and disposed of it. Removing and destroying it may sound harsh, but doing so before the gall dries out and the wasps emerge, will help to reduce the infestation. I fear if we don't handle these invaders properly, they will take over and cause major issues down the road.

Neat eh?

1 comment:

  1. Yes, very cool to see Heidi. I have seen one before too (PW) It took us a while to ID.


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