Tuesday, 18 February 2014

A Strange, Fluffy Gall

Recently I have published a post on galls, and one of the species that I briefly mentioned was the Moss Gall, formed by the Gall Wasps known by the scientific name of Diplolepis rosae. Today I have been researching this species, and I would like to share some of the interesting things that I have discovered.
Rosae's life cycle begins with the adult laying the egg in the Spring. Only a few males of the species have been found, so it is generally thought that they must reproduce asexually. The female will find a suitable host plant of the family Rosa (roses), then uses her ovipositor (an implement on the abdomen, rather resembling a sting, used to to deposit eggs) to lay eggs inside a leaf bud. When the tiny maggot-like larva hatches, it will begin to feed on the plant tissue around it. Though this part is not yet fully understood, it is thought that a chemical in the saliva of the larva stimulates the cells to enlarge and/or multiply, as I explain in my previous post (see the link at the top of this page). This is how the gall is formed. Even after the process begins, it is not always obvious from the outside of the plant. But eventually, the gall will spread out of the plant, creating a large outgrowth known as the Moss Gall. It is covered in long, green to red hairs - hence the name. It is often thought that the gall will become more red as it ages, however this is not always the case.

In this photo that I found the Internet, you can clearly see the long, curly hairs.
Several larvae may share a single gall, as seen here in this photo that I found on the Internet.

When Winter comes, the larvae will remain in their gall and take up the sedentary stage in their life cycle, known as the prepupa. This can be considered as a form of hibernation, as the prepupa does not move or eat. When Spring comes, it will shed its skin to reveal the true pupa developing beneath. In March, the adults begin to emerge, then the whole cycle is repeated.

In this image from the Internet, you can see the adult female's long limbs and thick thorax.

What an interesting life-cycle! I hope that you have enjoyed today's post, but if you want to find out more on Diplolepis rosae then there is plenty more information here.

Until next time, keep on the wild side!

1 comment:

  1. Hi, I'm a Cub Leader in Mkt Weighton and was wondering if you, and a grown up, would consider joining us for a nature walk and bug hunt down the railway line in our town?

    I think that the cubs would like to hear from someone their age who is interested in these sorts of things.