Monday, June 30, 2008

Attack of the Beetles Part II

Enemy #1: Flea Beetles
Battle outcome: Victory!
1)I found out flea beetles rarely actually kill the tomato (but they do destroy most lower leaves)
2)I transplanted my tomatoes in the garden after they were a bit bigger (>=10 in?) so even though they had fewer leaves after transplanting (since I buried the stems for stronger root system), I guess they had enough size and reserves to persevere through the flea beetle stress.
3)Diatomaceous earth! This is the best stuff ever! I had read that DE - a powder made of the fossilized shells of diatoms, super cool little phytoplankton of whom I've long been a fan - was good for flea beetle control; it's absorptive properties dehydrate them. Just when I was sitting in my garden, thinking to myself, "I really wish I had some diatomaceous earth!" but not wanting to go buy a big bag for a just a few sprinkles of it, a guy walked up with a sifter of diatomaceous earth, introduced himself, and let me use some. I love the community gardens! So I sifted some on the tomatoes that were having problems and there has been very little flea beetle damage since.

Enemy #2: Striped Cucumber Beetle
Battle outcome: ongoing, looking at possible shameful defeat
1) They keep breeding! A first generation emerges from overwintering in the soil, has the gall to mate all over my tomatillo, lay eggs, and then develop again in the soil, come out, breed... I think I'm seeing the second generation now. I've noticed a few smaller beetles, who look exactly like the adults except their black stripes are backed by gray, not yellow - I'm guessing these might be the youngins??
2)There's no good leave-on organic control for cuc beetles that I can find... There are some organic options, but they only work on contact with the beetles, meaning you can only possibly get the ones you spray directly. The other 23.9 hours of the day, they're all living the hedonistic beetle life on my plants.
I tried pyrethrin, (ex: Safer insecticidal spray) an insecticide derived from the crysanthemum family. It's certified organic, and usually mixed with an insecticidal soap. When I spray individual beetles, I've seen about 50% instant knock-down. But I'm not sure if I'm killing them or just temporarily inconveniencing them, giving them a renewed resolve to survive and breed more...
3)They really like smaller plants, especially cucumbers (surprise). They are not doing too much damage to my tomatillo anymore. It's pretty big, and apparently it was not their first choice in dining. I had been protecting the five-star meals inside walls of water and since I've taken off the walls, it's been an feeding frenzy. They eat the flowers and new shoots, and they very well might kill one of my cucumber plants.
4) I'm going back to physical blockage. I put the most victimized cucumber plant back in a wall of water with some cheesecloth over the top (so there's more room within the wall but the beetles are still blocked), as shown in the pic (of my patty pan squash they are also attacking) The other cucumber and melon are too big to fit within a wall of water anymore, so I might get some of the rowcover material and make a tent for them. It's their only hope.


  1. We have used DE on beetles. The best one that we have used is EPA registered for these pests and comes from DiaSource. This product is used in facilities, poultry houses and in Grain Storage - all are EPA registered.

    One must be careful with pyrethrims, they kill aquatic life and they can cause heart failure and severe asthma in children.

    DiaSource is a retail product and they provide the install service during construction. Check them out

  2. Thanks bug huntr!
    Yes, I'm aware of the danger to aquatic life and asthma, so I've used the pyrethrin very sparingly/carefully - just spraying a bit directly on the bugs I see. Children aren't around.
    However, I'm now going back to physical block method of physically covering the plant with row covers, b/c I can't be there to get even most of the beetles, and also I don't want to kill beneficial insects. I read that leafminers, for example, can get out of control if their predators get killed with insecticides,etc - basically, I don't want to throw off the balance.