I have two nicely flowering (not spreading) clumps of yellow loosestrife in different areas of the garden. Suddenly and for the first time two years ago in mid-summer tiny blueish/grey caterpillars appeared in great numbers.When they curl up the smallest ones are the size of pinheads, the largest may be a centimeter This repeated last summer and nobody has been able to tell me what they are or what to do. They chew the plants bare. I've picked them off, sprayed them off. When you touch them they curl up and drop down. This garden loosestrife is considered very hardy and resistant to any bugs etc.according to garden books and internet. They grow among lots of other perennials in my garden but none of the others are affected and I am worried about this summer. I've only discovered this website this week so I am wondering if someone out there has come across the same problem.

Anette check out the picture on the website below.

www.robsplants.com/critters/crawlers.php

Is that your 'caterpillars' ?

Sawflies it seems. If it's like the critters that go after delphiniums, they might over winter in th soil and leaf litter around the plants. Best defence is to clean up all dead leaves before the plants emerge in spring and watch carefully for any sign of them on the plants. If you catch them early you might be able to hand pick them off or just trim the top of the plant and let it regrow. Best to do any triming before the palnt gets to high or it won't have time to send up flower blooms.

Insecticidal Soap or Trounce can work if the larvae are small but you have to spray the larvae directly or it wont work.

Myself I prefer to eradicate than treat with spray after they become a problem

Hope that helps.

Pat

Thank you Pat, after two years searching high and low finally an answer. Yes, it is the blue/grey sawfly one in the photo re: Lysimachia Punctata which is yellow loosestrife. I'll follow your instructions and will see what happens.

I also experienced almost complete defoliation of two quite separate yet large patches of Lysimachia (Ottawa valley). In both these instances, however, the loosestrife was ciliata 'Firecracker'. I chose to simply whack both patches to ground level, ridding the garden of most and eliminating a food source for the rest. Like Annette's pilars they seemed to be specific to this plant. Subsequently, about a month later, one of these patches had sent up a new flush of foliage, to about a foot high, and was indeed flowering in a sporadic yet delightful fashion. I checked the above website and I do not think this to be the same creature - mine were a powder white, up to about 2 cm, curl and drop from plant quite readily if disturbed, hairless. Any ideas?

Hi Mthew:

Your description of your critters sounds exactly like what has been eating my Siberian Pearls dogwood for the past 3 or 4 years. They don't touch the variegated dogwood right next to it. I would love to know what the little monsters are.

Hi Mattew, this is a fantastic website/forum. Although I don't know what your caterpillars are you have identified a plant for us. When I checked to see what lysimachia-ciliata-firecracker look like I discovered that they are the ones I also have but nobody knew what they are called. I have let them spread because they do well in shade and appear free of any disease year after year. Anette