Scottish Rock Garden Club Forum

Cultivation => Cultivation Problems => Topic started by: Lawrence on August 19, 2015, 07:30:34 PM

Title: Caterpillars on Primulas
Post by: Lawrence on August 19, 2015, 07:30:34 PM
Have noticed some caterpillars on Primula forsteri and Primula pubescens and some allionii types. Some leaves have been fused together, some edges eaten, some skeletonised, the caterpillars are about 12- 15 mm in length I have also found one pupae about 10mm in length. Can anyone suggest the culprit and the control method please
Many thanks
Lawrence
Title: Re: Caterpillars on Primulas
Post by: Matt T on August 19, 2015, 07:57:09 PM
I wouldn't like to hazard a guess at what they are, but would suggest careful removal by hand would be the best remedy.
Title: Re: Caterpillars on Primulas
Post by: Diane Clement on August 19, 2015, 08:15:31 PM
Quote
leaves have been fused together
...  sounds rather like tortrix moth.  I have tried the sticky pheromone traps (made by Agralan) in the past and they did catch a lot of moths, although curiously not all of them were tortrix moths  ::)
there's an old thread here with various advice  ;D
http://www.srgc.net/forum/index.php?topic=5016.5 (http://www.srgc.net/forum/index.php?topic=5016.5)
Title: Re: Caterpillars on Primulas
Post by: Chris Johnson on August 20, 2015, 07:44:41 AM
These could belong to quite a large number of micro moth species, including members of the Tortricidae. Very few are colonial, where a lot of damage can occur. With individual occurrences like this, Matt's advise to remove them by hand is best. There is no need to reach for the nearest killing agent.
Title: Re: Caterpillars on Primulas
Post by: Dionysia on August 20, 2015, 11:18:43 AM
If they're green I get them every year, especially on the Dionysias. The first sign is a webbing binding a number of rosettes together. If I don't check daily they can damage quite a sizeable patch especially as they will also eat leaves or even sever rosettes. They can sometimes be detected when tiny but often seem to manifest themselves when over a centimeter long by which point they can cause damage quickly. Nothing chemical seems to work and the only thing that does is inserting a pair of fine, preferably dog leg tweezers behind the damage which can panic them into surfacing from where they can be dispatched. The good news is that there rarely seem to be more than one or two on each plant, the bad news is they often appear on the back of a plant so turn your pots if you don't already.
Title: Re: Caterpillars on Primulas
Post by: shelagh on August 20, 2015, 02:43:55 PM
Finger and thumb treatment every time.  You'll probably find they are very agile and squirmy, at least our are. 
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