Is anyone experiencing a plague of sciarid flies this year? I've had a few in previous years and controlled them with the sticky yellow strips you get in garden centres. A couple of weeks ago I noticed that there were a lot of these flies on and around my cacti/succulents so I bought some of the yellow strips. Within a week, one of the strips had collected over 200 of these pests and I threw it away and replaced it with a further three sticky strips. In only 4 days these have collected well over 100 flies; see photos (there are more flies on the reverse of the strips).
All my plants are in a conservatory as I don't have a greenhouse at this property and there are no other plants in there. All my cacti and succulents have grit on top of the substrate. This has always deterred these flies from laying their eggs in the past. I have repotted a fairly large number of plants this year and there was no sign of the sciarid fly larvae in any of the pots.
You will see from the photos that there are no other flying insects trapped on the strips; only these sciarid flies.
I don't understand why there should be so many of these flies this year. Has anyone else experienced an epidemic and is there anything else I can do to deter them? I would rather not use an insecticide.
You can enlarge any of the photos by clicking twice on it.
Last edited by rodsmith on Thu Sep 07, 2017 3:58 pm, edited 1 time in total.
Rod Smith
Growing a mixed collection of cacti & other succulents; mainly smaller species with a current emphasis on lithops & conophytum.
None down here, but did 'they' inadvertently come in with a recent batch of compost.
When I lived in East Hertfordshire, sciarid was really bad due to the many growers of mushrooms - they love their compost, in particular.
Tony Roberts
Treasurer, Haworthia Society
Chairman, Tephrocactus Study Group
Moderator, BCSS Forum
Kent
(Gasteria, Mammillaria, small Opuntia, Cleistocactus and Sempervivum are my current special interests)
Hi Rob, yes I've definitely noticed higher numbers this summer too. It's great news for the Pinguiculas growing in my carnivorous plant greenhouse where the problem seems worse. There are some, but not as many, in my succulent plant greenhouse presumably because they don't do quite so well in the dryer environment.
Cheers
Gary
Plant Interests
cacti & other succulents, carnivorous plants
Thanks all for your replies. For several years I've used coir with added grit, vermiculite and Tesco cat litter. The coir is bought in blocks and water added to rehydrate it, so no chance of eggs or larvae being "imported" in that way, I would have thought. The bulk of my collection will be dry over winter but I do have a few conophytums which will need the occasional drop. I'll be interested to see if the flies disappear completely and, more importantly, if they return next year.
Rod Smith
Growing a mixed collection of cacti & other succulents; mainly smaller species with a current emphasis on lithops & conophytum.
As Ralph says they like peat based composts. A nurseryman told a friend of mine whilst many compost firms sterilise most of their ingredients such as the soil, they often do not bother to sterilise the peat since that is supposed to be sterile anyway and so is mixed in later. However it may have acquired insect pests after it is milled.
How true this is I do not know, but some claim they have had sciara flies in commercial supposedly sterilised composts they have bought.
Nottingham Branch BCSS. Joined the then NCSS in 1961, Membership number 11944. Cactus only collection.
I used to be plagued with these until I bought a'Hotbox' sulphur vaporiser. I use it three nights a week for three hours at night. Ne xt morning the greenhouse stinks of bad eggs' ,but only temporary!
Really successful, gets rid of spiders too.
Best Wishes
Pjt124
