Q & A: Insects

praying mantisGot a gardening question? Ask Susan! What follows are reader questions. Each time a new one comes in, I’ll add it to the top. To ask a question, drop me a note at Susan@susansinthegarden.com.

 

 

Q: Our covers (and hoops) on the raised beds were no match for the snow.  Did your new thicker row covers work?  If so, could you please let us know where you got them? JB

A: We have 2 raised beds with hinged lids that are covered with agricultural insect netting. They have done well so far for 2 reasons: 1) The hinged lids are quite strong, and 2) In November, we secured a layer of plastic over the outer tops of each hinged lid so that most of the snow would slide off of them. The hinged raised bed lid is a do-it-yourself project from my book, The Vegetable Garden Pest Handbook. The agricultural insect netting came from a company that used to be called AgFabric.com, but they changed their name to GardenPort.com a few months ago. Here is a link to their insect netting options and sizes: https://www.gardenport.com/collections/insect-netting. We have been extremely happy with the insect netting so far. This will be its second season in our garden and I feel pretty confident that it should do equally well this year. It kept out aphids, cabbage butterflies, and leafminers with no problems at all. If you haven’t seen my video where I compared the different types of covers we’ve used, here’s a link to it: https://www.youtube.com/watch?v=uhDRiLX5070

Q: I’m hoping you can give me advice about aphids.  Each year I plant lots of red & yellow petunias in Spokane and at our cabin.  In each pot I replace 1/2 the old soil with  new potting soil.  For the last 2 years my petunias grow beautifully and about mid-August I see the plants changing.  I can see aphids on the plants.    I have sprayed with water,  soap water & aphid spray.  Because my pots get so full & overflowing it’s almost impossible to spray everywhere.  Eventually my plants look terrible.  After doing some reading I am wondering if aphid eggs live in the soil through the winter.  If so, what can I do?  It would cost a fortune to start over with new soil.  Before I plant is there something I can treat the soil with and keep the aphids from hatching, if that is the case? Thanks and I would appreciate any advice you can give me. JS

A: That is so odd about your aphid problem and it certainly sounds like you have tried just about everything. However, you are correct that the aphids are probably coming from previously-used potting soil. At the end of each growing season, female aphids mate and then lay eggs on plant debris. The eggs overwinter and hatch in the spring. So I believe that’s why you’re ending up with so many aphids each year. I’m glad to know that you are using organic methods because that is so important. Especially when it comes to dealing with aphids, because pesticides will also kill beneficial insects. And there are so many beneficials that love to feast on aphids! So you don’t want to inadvertently kill the good bugs. I don’t know of anything you could put into the potting soil to kill the aphids. I do know that some folks sterilize their potting soil by baking it in the oven, but I’ve heard it smells AWFUL! So you probably won’t want to go that route. Good luck.

Q: We’re so intrigued by the new agricultural insect netting you have over your lettuce bed in your 2022 #11 video. We understand you’re
still testing it but we would like to try it too in the meantime. Can
you give us the product name and source for that? MD

A: I have been asked this question so many times now! We purchased the garden insect netting from Agfabric.com. It comes in different sizes and widths. It’s my understanding that they are selling out of some of the smaller sizes, but here is a link to the type of netting we bought. If you can’t find what you need, try Agriculture Solutions. Before you order any, be sure to calculate the width by measuring from the ground, up and over your hoops and back down to the ground on the other side!

Q: I’m having no luck finding a source of tulle netting (to keep insects away from cabbage family crops) that is wide enough to cover raised beds that are 4 feet wide, which is how all mine are built.  The widest I’ve been able to locate is 54 inches.  Do you have a source you can share without a lot of difficulty?  Thank you for your help and your wonderful website!! HY

A: You might need to order the tulle online to find wider widths. For example, I just found this: https://www.tulleshop.com/products/white-108-inch-tulle-fabric-bolt-50-yards. Amazon offers a lot of deals on it, too. I did a search on “tulle 108″ wide” to find these sources (and more). It might be more quantity than you want but the bolt prices are very good. No matter what you’re looking at, try to look at photos showing how small the holes are (important). You could probably go with any color you want but I usually buy white or ivory.

Q: I had a real battle with leaf miners this year. Other than covering the plants do you have suggestions. GC

A: I’m afraid there’s no other organic solution for dealing with leaf miners. The only way to thwart them is by covering the plants with floating row cover the moment you plant the seeds and only uncover them to harvest or weed. The adults are flies that lay eggs on the leaves, which is why the row cover works. Leaf miners are extremely frustrating but row cover is an easy solution.

Q: Is there a rule of thumb about how deep the box of an insect hotel needs to be? I have a lot of bamboo, other vegetation, to use, but I don’t know how far into a space the insect has to go in order to nest safely. CH

A: The rule of thumb is about 6-8″ of depth for insect hotel compartments, as well as for bamboo sticks, mason bee tubes, branches, etc.

Q: When is best time to place your insect hotel outside? Is it too late to place it in the fall?  And does the hotel attract yellow jackets instead of mason bees? BW

A: Fall is a great time to put it in place because in the spring, once the mason bees emerge and mate, the females will be looking for a place to lay their eggs. So then you’d be ready to go. It does not attract yellow jackets because they nest in the ground. I do fill each of the cubbyholes from bottom to top so there isn’t room for wasps to build a nest.

Q: In a recent YouTube video you mentioned covering broccoli to avoid insect problems.  I recently harvested my broccoli and found these worms (photo of green cabbage worm).  Is this what you were referencing?  I soaked the broccoli in salt water and carefully picked thru it before blanching. Can I do anything to the remaining plants to eradicate these pests? KF

A: Yes, the photo you sent is of a cabbage worm. Once they’re in your broccoli, the only thing you can do is exactly what you just did: soak them in salt water and pick out the worms. In the past, I usually missed the occasional worm and it ended up on my dinner plate. Ewww. So for future plantings of broccoli, I would recommend covering the plants right at the start with either floating row cover or tulle (bridal veil netting) to prevent cabbage butterflies from landing on the leaves and laying their eggs. It’s a very simple solution.

Q: How do you keep squash bugs away? JF

A: I somehow have been lucky in that I haven’t had to deal with those nasty bugs. However, I’ve heard that the best way to keep them from your plants is to cover them (or the seed you’ve just planted) with floating row cover right away and keep it on the plants until they start to bloom. Apparently the bugs lay eggs early in the season and that is the start of the problem. By covering the plants, you are disrupting their life cycle. 

Q: I recently read your post about covering broccoli crops to avoid bugs. My broccoli has been in the ground for about 6 weeks now. Is it too late? CB

A: It’s not too late to cover them — esp. if you’ve had problems with cabbage worms in the past. What I would do is examine all of the plants’ leaves first, and if you see any eggs or worms, get rid of them. Then put the cover over them.

Q: I’m very interested in the insect hotel & mason bees. Unfortunately we
are cursed with lots of wasps and I’m allergic. I fear the wasps will
take over the hotel and I will just have made my problem worse. Any
advice?

A: We feared the same thing so here’s what we did: We filled each section of our insect hotel from the bottom all the way to the top so there wouldn’t be a “ceiling” for them to hang a nest on. We do have a lot of wasps in this area yet they haven’t been a problem in the insect hotel at all. And I’m guessing it’s because we packed it with materials.

Q: I planted a 12 foot row of turnips and another one of spinach in the same raised bed in May, separated  by 12 inches.  I got no usable items from either.  The turnips were full of small worms.  It was not like an onion or radish that might have a small hole that you cut away to use the rest.  It was totally unusable.  SS, Spokane

A: It sounds like the turnips had root maggots in them. Next time you grow them, you might try covering them with some floating row cover as soon as you plant them in order to keep the adult fly from laying its eggs on them.There is an information page in my Organic Pest Control Guide that explains how row covers work.

Q: Susan, do you know of any organic spray to stop leaf miner activity?  I forgot to put a floating row cover over the pony-pack of chard, and now the leaves are being eaten up one at a time. TM, Spokane

A:  That’s a shame! I don’t know of any organic spray that will work, esp. since the leaf miners are in between the cell layers of the leaves. Maybe you can pull off the infested ones, cover the plants, and see if they’ll do OK from that point on? And for next year, be sure to use a floating row cover as soon as you plant your chard (or spinach or beets, for that matter) so you won’t have to deal with those pesky insects.

Q: Susan, our crops are being decimated by earwigs. I can’t believe what has happened to my beautiful basil plants. There is literally nothing left but a few “strings.” Do you know how I can control them organically? Thanks! LW, Spokane.

A: You can try using diatomaceous earth (DE), which you can find at garden centers. It looks like flour, although it’s actually made from the fossilized remains of diatoms (algae). Here’s how it works: even though we can’t feel it, there are tiny sharp edges in the diatomaceous earth. You sprinkle it around the plants, an insect walks on it and their skin gets punctured by the sharp edges. Then they essentially dehydrate and die. I think it’s worth a try. This is organic, by the way. I had a problem with pillbugs nibbling on the stems of my cucumber and melon seedlings, and DE worked really well. One earwig-trapping method that we used a few years back involves taking a piece of cardboard and folding or rolling it a bit. That will expose those openings in between the layers that make up cardboard. You put it out in the garden in the evening, then pick it up in the morning and, hopefully, it will be full of the little stinkers thinking they’ve found a lovely place to hide until nighttime. And of course, you then toss it in the trash. I hope this might work for you. Good luck!