by Erin Hollis
Description: The day flying adults (may be seen sitting on the leaves of squash early in the morning) are primarily orange and black superficially resembling a wasp. The forewings are covered with metallic olive-brown scales. The hind wings are mostly clear with a brown edge. The abdomen is bright red and ringed with black bands. Adults have a wing spread of about 1 – 1.5 inches.
Their Arrival: In Central Texas expect them late Spring/early Summer (usually mid April in my yard) and again in late August
Life Cycle: Squash vine borer refers to a moth that lays reddish-brown eggs singly on most varieties of squash plants. The adult moths will lay their eggs on the tender stems and shaded parts of the baby squash plants. The eggs will hatch in about a week to 10 days and the larvae begin boring into the stem.
The larvae are white or cream-colored with brown heads, growing to almost an inch in length. The larvae will stay in the stem of the plant for about four to six weeks.
Because they feed on the center/inside of the stems, they cut off water and nutrients to the plant, causing it to wilt. Here are some signs there are larvae in the stems of your squash; the obvious wilting of the leaves and stems. Holes in the plant’s stems, usually at the base, where the larvae burrowed inside. Sawdust-like frass colored anywhere from orange-yellow to green coming out of these holes. Signs or rotting in the stem where they have eaten them from the inside out.
When full-grown the larvae climb from the stems and pupate a few inches deep in the soil overwintering there. They emerge as adults in the spring to mate and lay eggs.
Now What Do I Do:
Preventative measures: Soil can be tilled before planting to reduce the number of larvae that are in the soil. Birds may come eat the pupae but look for them and pick them out as you come across them. As your vining varieties grow, you can pile soil every 2 feet or so on the stems. This will encourage rooting at these places on the stem, so that if the borer gets in the stem the plant may still have a chance to grow.
Row cover can be used to protect new crops of squash you may plant, just remember to remove the row cover when the squash has blooms to allow pollination to occur (or hand pollinate). If you are growing in a section that had SVB the previous year/season make sure to also perform the next measure, check frequently for SVB’s and their eggs. They will be trapped under your cover putting those plants in harm’s way but potentially protecting other plants in your garden.
If you leave the squash uncovered, monitor the stems regularly (at least a couple times a week) for eggs. Look along the stems (top to bottom) of the plant and both sides of the leaves, even on the flower buds for the eggs to see if you can locate the solitary copper-colored egg. Remove the eggs. Sticky tape, such as masking tape, ensures they don’t fall into the soil where they can hatch and return to the stem. Another method of removal would be to scrape them off into a container of soapy water.
If you want to leave your plants covered, and since squash are normally bee-pollinated (and the row cover excludes the bees) you will have to take the place of the bee. Find an open male flower (they have the anthers with pollen on them), and dab it onto the female bloom with the pistil. One male bloom will pollinate five to eight female blooms. A cotton swab or small paint brush may also be used, and should occur before 10 a.m. for maximum success. Each flower is open for only one day, so daily pollination is recommended.
If you have squash vine borers in your squash:
Vigilantly keeping watch for tiny holes with brown “sawdust” around them. As soon as you see one, shine a flashlight under the stem (in the evening) to illuminate the borer on the inside. Once you’ve located it, you can stick a pin, needle or small knife through it to stop it’s destruction.
For limited damage, you can remove the leaf stalk if it’s not on a main stem.
Another way to stop a larvae is to remove it from the stem. Slit the stem lengthwise with a sharp knife, I like the thin blade of exacto type craft knife, I cut the larvae and let the stem heal, without removing it. Or you can remove the larvae and then cover the cut stem with a pile of soil on the cut portion of the stem to encourage new roots to grow.
If infested, vines should be removed and destroyed (not composted unless you are sure your compost pile temperature reaches high enough to kill insects) soon after squash harvest. Added measure would be to split stems and joints open to remove and destroy any larvae.
Other Methods of Control found in various articles:
Yellow Sticky Traps: They’re attracted to yellow. (Word of caution here. I’ve found all things stuck to these. From bees to good spiders and lizards).
Catch Them: The best time to catch adults is around dusk and dawn. If you head out to your squash plants around this time, you may notice adults buzzing around and be able to catch them. (I haven’t been about to get close enough to them to catch one. They move pretty fast, when needed!)
Timeliness: Planning ahead, you could have more seedings started so you can replace the destroyed plant. Master Gardeners often recommend planting squash every two weeks in order to protect your crop. Placing new seeds in the ground may work as well. Just keep them watered as the days get hotter. At some point the SVB’s will disappear until their next “window of opportunity”. Usually mid to late August for Central Texas. Although, I did read in at least one article that they stick around all summer and into November and December. I haven’t had this experience. This was an article for a South Texas audience. Planting really early (March) and then again really late (August) to get harvests while they’re not as active.
Nylon Stocking: Wrapping the stems with strips of nylon stockings, to prevent the larvae from getting in them. (Maybe wrap gauze around the stems.)
Flexible Wire: Insert a thin flexible wire. Instead of cutting into your plant, if you notice a burrow hole, an alternative method is to take a thin, sharp wire and slide it into the hole in the hopes of, essentially, skewering the larvae.
Remove Infestation Early: Getting rid of finished vines and tilling the soil in the fall and spring to get rid of overwintering pupae because these can hatch and damage next year’s crop. At the end of the season. Pull up and destroy all leftover plant vines quickly. You may think that SVBs are done after your squash are harvested and the plants seem to be dead or dying, but this is a mistake. Quite often, larvae will continue to develop inside the vines until they’re ready to climb out and burrow into the soil—unless you dig up the vines and get rid of them. You should also do this with any plants that have been killed by borers during the season as well.
Rotation: Planting squash in a different location each year, so that if some pupae do overwinter in the soil, they won’t find the new plants. (Not realistic, in my opinion, since in most home gardens the size is fairly small and the SVB can fly!)
Plant Extra Squash: Some for you and some for the bores. There are only so many eggs they can lay and they shouldn’t be able to damage all of your plants. I’ll continue to sprout some squash so if you want another plant in a few weeks or later this summer just check in!
Squash Resistant to SVB:
Acorn squash, known as a winter squash because it stores well into the winter, has solid stems and is not usually affected by squash vine borers.
Squash in the Cucurbita moschata family are especially resistant. These include Butternuts, Tatume, and my personal favorite Tromboncinos, a vigorous Italian heirloom that can be eaten early as a summer squash or allowed to grow huge to be stored as a winter squash. If you grow Tromboncinos, be sure you have a lot of gardening space and, ideally, a fence or large, sturdy trellis they can climb on.
Trial in progress: I am trying tulle (bought on amazon - comes in many colors and widths/lengths). Worked great over winter against cabbage moths, etc. Now working great against the SVB and grasshoppers!
We just passed the New Moon phase and are now approaching the First Quarter and are in Waxing Crescent. It’s a good time to plant leafy greens, cereal grains, and herbs that do well in heat. During the waxing of the moon (the period extending from the day the moon is new to the day it reaches its fullest point), the moon pulls moisture upwards. Seeds do well during this time because moisture is available at the surface of the soil. It’s always best to try to transplant and seed-in with the coming rains that are in the forecast.
Direct Seed or Transplant Warm Season GreensTexas A&M Agrilife Extension Leafy Greens Growing Guide.
Seed in Cereal Grains & Cover Crops
For the health of your soil, moisture retention, and to prevent weeds, keep your soil covered at all times with cover crops, compost and mulch. Bare soil invites weeds. Consider planting summer cover crops, such as buckwheat or black-eyed peas, or flax. Add compost, then mulch, to other bare soil areas. An inch or two of compost, and then two or three inches of mulch.
Transplant or Seed-in Herbs
A lot of herbs were damaged in the snow storm. If yours are not showing signs of life, here are some warm season herbs that can be transplanted.
For more ideas on Ornamentals, Perennials, and Herbs, visit the Central Texas Gardener and The Natural Gardener lists online. Download the Texas A&M Extension Planting Chart and Varieties Chart on our website.
This Saturday we harvested spring and fall crops and are still planting flower seeds to encourage beneficial insects. We also noticed some cute new visitors on our purple potatoes.
ZUCCHINI HARVEST We are already harvesting our zucchini! This organically grown zucchini was a transplant grown by Gabriel Valley Farms, in early March. Right on schedule and no signs of squash vine borers. 🎉 We fertilized our beds in the fall with recycled mushroom blocks. Studies have shown that many different types of plants, which depend on #mycorrhizal relationship with fungi do really well with spent mushroom substrate as a fertilizer. This year, the zucchini plants clearly did well considering we've had trouble with SVB in the past. Living mycelium accumulates, stores, and redistributes carbon, nitrogen, phosphorus, and other nutrients. You can sign up to get recycled mushroom blocks below. Next week we will be eating zucchini bread at our volunteer day at Zilker Botanical Garden!
GARLIC HARVEST We planted elephant garlic donated by AOG member Kurtis in the bed in early October and it was ready to harvest last week. Experts from Seed Savers Exchange say the plant is ready after three or four leaves have died back but five or six green leaves remain. Avoid waiting too long because the cloves will begin to separate from the bulbs in the ground. Do not wait too long or the bulbs will begin to separate in the ground. Loosen the soil with a shovel or pitchfork and then dig the garlic carefully. Do not pull the stalk or it will separate from the bulb. Gently brush most of the dirt off. Tie plants in a bundle of 6-8 plants and hang in a shaded, dry, well-ventilated shed or garage. Leave plants hanging for 4-6 weeks so that bulbs can cure. Learn more about growing and storing garlic in Central Texas.
CORIANDER SEED SAVING After enjoying seeing all the beneficial insects such as the lady bug beetles on our flowering cilantro, the flower heads formed seeds and dried out. Maya, Magda and Danielle collected the seeds by cutting off the seed heads and put them in a container. If your seed heads aren't dry yet, you can hang them in a brown paper or cloth bag until the plant dries and the seeds fall off. The seeds can be saved for next year or used for cooking as they are a popular spice for many recipes.
LEAFHOPPER NYPHMS ON POTATOES Our potatoes stems were covered with some unusual looking bugs that was eating the green leaves. After some research using iNaturalist to identify them, we learned they are the two-striped Plant hopper. This bug appears to nosh lightly according to this article so we will keep an eye on this cutie.
This past week I visited long time member David Kraemer to pick up some citrus that he propagated. Here he is with his new haircut and his lemon drop citrus tree (hybrid of a lemon and kumquat) that survived the winter storm.
While there I couldn't help but notice all the swallowtail caterpillars in his garden. The host plants of the Black Swallowtail butterfly include such plants as carrots, parsley, dill, fennel, Queen Anne's Lace and rue. The Anise Swallowtail caterpillar feeds on anise as well and reportedly citrus plants also.
The plants that adult butterflies eat (actually they “drink” nectar from the flowers) are called nectar plants. Each species of butterflies has specific host plants on which the adult butterflies lay their eggs.
The butterflies are particular about where they lay eggs because their caterpillars must have that distinct host plant to survive. The caterpillar will not eat if it does not have access to one of its specific host plants and will die. It's important that you leave some veggies for our butterfly friends.
David's Nigella, love-in-a-mist was blooming as well. This stunning annual garden flowering plant with ferny foliage that does well in alkaline soils. It belongs to the buttercup family Ranunculaceae. Nigella is generally considered to be an ornamental plant, but according to PFAF, the seed can be used raw or cooked, and is normally used as a condiment with a nutmeg-like flavor. It can also be used to produce an oil. The fresh leaves and flowers have a peppery flavor similar to watercress.
Check out David Kraemer's member profile on our YouTube channel.
As things continue to establish in the garden and fall crops fade, we're starting to see some new visitors at the teaching beds at Zilker Botanical Garden.
In this video Austin Organic Gardener Madelynn shares helpful tips on watering for moisture retention, companion planting, and tips on handling insects the organic way.
Don’t miss our next online guest, Jay White, the publisher of Texas Gardener Magazine who will be presenting more on this topic with his “Pest-free Organically” presentation on May 10th at 6 PM CST.
For more ideas on Ornamentals, Perennials, and Herbs, visit the Central Texas Gardener and The Natural Gardener lists online. Download the Texas A&M Extension Planting Chart and Varieties Chart at AustinOrganicGardners.org.
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