Once upon a time it was the summer of 2011 and Mr. Plantasmagorical was really happy because so far he had experienced no nasty garden or greenhouse plant chomping infestations of any appreciable kind. Even the greenfly seemed to have taken a vacation. However, you can be guaranteed that every fairy tale has at least one hideous, child scaring monster lurking in the wings, just waiting to leap from behind the curtain to throw a spanner in the “happy ever after”. In the case of the summer of 2011 bliss the monster had no spanners to toss but a whole biblical plague of earwigs. I have never seen so many of the little devils. they even crawled into and lined the fluting in plastic greenhouse panels. Normally, earwigs are no problem, they leave well alone, but this kind of infestation leaves its mark. Some of my precious seedlings first leaves and even some of my cactus began to show the tell tale signs of what happens when too many earwigs have too much time on their hands (or mandibles). Little earwig mouth sized nibbles began to appear everywhere!
The first course of action was the usual clean-up. All those piles of pots and anything laying around was cleaned, moved, removed or whatever it took to reduce the classic hiding places for the wriggly beasts. All though was to no avail. I was overrun, they just kept on coming.
I have never been a great lover of using chemicals in my cultivation exploits but I came very close to ordering a ten tonne handy family pack of napalm when I discovered I was wearing down so much shoe leather from stomping on the earwigs! Anything that moved in the greenhouse got sole! Yes, the cat may never forgive me, but I’d developed a hair trigger response to mobile critters on the floor of the greenhouse.
A habit I have got into over the years in my pest control exercises is that I place sundews (Drosera spp) in every spare spot in the greenhouse. These are the sticky plants that all those flying bugs such as greenfly, whitefly etc. can not resist. For me there is no more effective biological control of aerial pests than the use of these carnivorous Drosera spp. There is a slight eco downside involved in the maintenance of the carnivores however…they only grow in peat. You can add vermiculite to the peat though, and this helps aeration of the soil as well as moisture retention whilst helping to reduce the amount of peat per pot. You also have to keep them in a tray filled with water at all times. My usual trick is to use carbonated water from Tesco at 16 pence a bottle! This approach works for most of the carnivores you may encounter. So, I wondered if any of the carnivores would be useful in my anti-earwig war. My wondering came to an end when I happened to be wandering through Perrywood Garden Centre in Essex during early summer, as I do. They had just got their stock of carnivores in and they were not in the usual boring, brown, plastic pots but inside a plastic flask. It was this format that initially caught my eye…being a sucker for a good point of sale idea! However, on closer inspection the carnivores were really healthy and I thought I must try a few different types in my earwig war.
The Sarracenias are the pitcher type carnivores with modified leaves that have evolved to wrap around into a tube shape. The mouth of the tube has glands that produce nectar like substances to attract the bugs. The tube itself is lined with hairs and waxes that do not allow the bugs to get a grip when they get inside the tube, thus trapping them. The lower part of the tube contains a fluid into which digestive enzymes are secreted by the cells of the plant. Bugs attracted to the nectar generally fall into the tube whilst “high” on nectar and once inside are unable to exit, leaving them to be slowly dissolved by the enzymes within in good old fashioned, wicked witch, I’m melting stylee! This process of bug bashing is so highly advanced in some carnivores that they also produce chemicals to “anaesthetise” or immobilise bugs. Some Sarracenias produce conine for example, the poison found in hemlock. The fact that carnivores produce so many chemicals has led to their use as medicines by mankind. One of the most important chemicals produced by these plants is plumbagin, a substance that is extremely useful in the treatment of lung complaints ranging from asthma to TB. In my time as a herbalist a syrup made from Drosera was a standard issue item in the dispensary!
However, when I first got the Sarracenias into the greenhouse nothing happened. I also got a couple of Venus fly traps and they had more success in catching a few simply from the random wanderings of the earwigs. Then I decided to experiment. It seemed to me that the tubes of Sarracenia were natural hiding places for earwigs and I could not understand how not a single one had wandered in yet. So, what I did was to place a couple of earwigs into the tubes and observe how they got on. I kind of suspected they may be able to climb out. Indeed, once inside, they could not get out. So with a smile on my earwigicidal face I left them to be slowly dissolved by Mr. Sarracenia. That, I thought, was that. I didn’t really think that any more would wander into the Sarracenia, and I was certainly not going to feed them to the plant, so at the very least, I got another very interesting plant in the greenhouse. To my surprise though, over the next few days, earwigs seemed to beat a path to the Sarracenia and a big mess of part digested earwig mush appeared at the bottoms of the Sarracenia tubes. The Sarracenia itself was obviously benefiting big time, its growth took off, and last week I had to sign it up for Weight Watchers! I was so surprised by this effect that I now have several Sarracenias in strategic positions doing a fantastic job on the earwigs!