If you have a squash bug (SB) or squash vine borer (SVB) problem, it can be a big problem. Some areas have even greater trouble due to increased season length and mild winters.
Despite SB’s greater versatility, I hate SVB even more. It’s utterly devastating, and requires much more attention ahead of time, because once the plant wilts, it’s pretty much too late.
Even if you’re not growing yet and don’t have any problems, push through this one anyway, just in case. You’ll need the fixes and preventatives on hand ahead of time.
Recognize the Enemy
SVB is a moth larvae that chews into and then up through vines of susceptible cucurbits. The plant suddenly wilts, then dies. It limits its destruction to cucurbits and doesn’t usually bother thin-stemmed melons or thin-stemmed gourds.
The SB is a beetle, and spawns freakish little spidery babies that go through green and gray stages. In addition to munching all kinds of plants, they spread disease. There are similar-looking pests with very similar control and prevention difficulties.
The eggs are the best identifier ahead of time. SB lay tight, regular patterns. SVB lay fewer, more irregularly.
SVB usually lay on stems, as close to the base of the plant as possible, but I’ve found them upwards of 1’ above the ground and some trailing up under leaves.
SB wants to lay on the underside of leaves, but I’ve found those diamond clusters on stems, too.
Check other plants, too – It’s not as frequent, but SB will lay on beans, peppers, sunflowers, okra, etc. SB adults will be found anywhere, too.
Conventional Traps, Spray & Powder
In their early stages, SB is somewhat vulnerable to Sevin spray. Powder isn’t super effective and it doesn’t bother the eggs. If SVB larvae aren’t crawling across it as they hatch, it doesn’t bother them, either. Spray can be more effective on more of the life-cycle stages, but it’s “more” – it’s not total wipe-out.
Some find neem oil effective, particularly in the early life stages.
All of them have to catch the bugs to be effective. SB are active enough to evade that spray by leaping away. SVB are inside, so you have to fill those stems to catch them.
Big Ag may be able to blanket enough dust and spray to do so, but most home growers even with a tow-behind disburser are going to struggle to blanket a big enough area fast enough.
!!! – Pesticides aren’t super effective on SB and SVB, but they are wicked effective against pretty much every single beneficial bug in our gardens, from worms and fireflies and their slug-hunting larvae, to pretty much every single pollinator, bees to butterflies to hoverflies and wasps, and can even affect the gut microbiology of hummingbirds and bats. – !!!
Traps work well, but require specific attractants and have to be replaced or rejuvenated.
Squash vine borers can pop up after years of not growing squashes anywhere within 200-500 yards. Squash bugs are the same, with an added problem: They like squash. They don’t need it.
That means crop rotations aren’t super effective in breaking this particular pest cycle.
The smaller our spaces, the less effective it becomes.
The mobility of the moths and adaptability of the beetles means that for most home-consumption and small-plot growers with less than an acre (‘bout a football field) per crop butting into another half- or full acre of clean, bare earth, the advice to keep a “clean” garden and avoid mulches doesn’t actually help much.
Without that space, there are too many other options for them: tree and shrub windbreaks, perennial crops and ornamentals, wood piles, overgrown ditches and fence lines, woods, lawns and pastures, straw and hay piles, gaps under sheds.
Weigh that against the values of mulches before going the bare-earth road.
Unfortunately, control once they’re established is difficult, too. Enough to make you fantasize about spraying gas and lighting a match.
Tried & True: Squish ‘Em
Good luck catching the moth. (If you find something that doesn’t affect good bugs, please share.)
To help lower the load for the beetle, carry a jar to the garden to flick them into, and a board you can squash them against.
That board is handy for collecting SB’s – so is cardboard. Lay a chunk near the plants, flip it, stomp.
Tried & True: Pluck Eggs
Attentively checking stems and leaves for little red eggs is the most effective way to control damage.
You can scrape with a butter knife or thumbnail, or try wrapping good, sticky duct tape or packing tape around hands or fingers. You’ll have to press pretty firmly.
I do not just let the eggs fall to the surface under the belief stuff will eat them there (maybe, but maybe not). Nor do I deliver them to birds (some may escape). They get carted to the trash – the trash. In a world without trash, seal them in jars/pails.
Tried & True: Stick Juveniles
I like tape for snagging itty-bitty, speedy SB babies, although you have to really stick them or they can wiggle free.
There’s also the theory of stabbing the SVB by sticking pins/toothpicks in the stems and base of squash either as a preventative or as soon as frass is visible. It has merit, especially if a plant is months into growing but isn’t anywhere near harvest, particularly in a situation where we need this food.
Squashes develop really wide bases, though, and may have more than one larvae, so make sure you’re thoroughly stabbing to kill. They can easily crawl out and chew in elsewhere otherwise.
Foil – Fail
I have tried full-sheet widths of foil in a ring around squashes from the time they pop up. I have interwoven strips around as much of the base of the vines as possible.
The foil at the base in a wide collar akin to brassica collars might be helping, but it’s limited. I have no luck with other materials, either.
Again, I see SVB eggs way up on stems, not only at the base – mama lays on whatever’s exposed, and babies adapt.
Conditionally: Sacrificial Hubbard
Yes, SB-SVB do like Hubbard. I have ringed lots with it, with 20-yard gaps to the nearest other squash, and thrown it in right beside the other cucurbits. Sometimes it’s the only victim or the damage elsewhere is limited, but it’s at best 50-50 and it does nothing to lower the pest loads.
In Big Ag, the Hubbard goes out early and farmers kill the bugs on it to lower pest loads for direct-seeded cash crop squash.
Otherwise, once they’ve killed the Hubbards, SB/SVB have plenty of time to leap over to other cucurbits and kill them, too.
Yellow Traps – Fail
This is where you hang something fairly smooth and happy yellow (cups, frisbees, painted canning lids, yogurt tubs), lightly coat it in something semi-sticky or clogging (kitchen and garden oils, thinned-down glues), and hang it so that itty-bitty munchers get snagged and stuck or coated and suffocate. Wipe, re-coat, repeat.
I have never actually seen hoverflies, fireflies, brown wasps, or striped and fuzzy bees attached, no big butterflies or moths, just the teeny-tiny stuff, so it’s not really hurting. However, I’ve only nabbed juvenile SB on versions stuck down into the dense sections of foliage or laid out in a ring under foliage, and it’s few and far between and mostly a waste of time and resources.
(Again, it can take significant pressure to snag those SB babies – you need a serious level of sticky, and for them to willingly crawl onto it to get stuck, or to fall/jump onto it; they’re not flying or leaping to it on purpose like white-fly.)
Cup Collars – Fail
These guys are effective against some types of pests for other types of crops, just like foil and cardboard collars, but, again, SB lays mostly on leaves and is not restricted to cucurbits – it just likes them – and SVB will lay well up on the mature stem, with the wormy larvae crawling down as far as possible to enter but in no way restricted to entry right at the base of squash.
In the time when the plants are small enough to fit in the cups, their vines aren’t actually vulnerable to borer larvae, still too skinny.
Too, those cups only reach a couple inches up. Any SVB that come by later are going to have nice, exposed stems and leaves protruding to lay on, with their young readily able to slide down and chew in.
Squash are big plants with wide bases and sprawling vines by type – you only contain them in a cup for a little while. Then, there are months of season left for SVB to lay on exposed, viable vines.
So… once again, while effective against some pests, it’s a waste of time and resources for SVB/SB.
Semi-Helpful: Bury Nodes
There’s the belief that once the adventitious root nodes of longer vines is buried, the adult SVB moth doesn’t know it’s there, and won’t lay her eggs there to burrow in. The idea that she can find a seed-started stem but not a buried node… I don’t know how that even gains traction.
Plus, again, she’ll lay way up on stems. Where they are doesn’t matter.
However, there is a benefit: It creates another feed point for the plant.
If you can kill the larvae in the original stretch(es), active nodes can keep the plant alive long enough to mature any fruits further down the vine.
Tried & True: Row Covers
They work, but there’s some issues that come up, because you have to seal the edges.
SB require really sealing the edges. They’ll crawl under any loose sections. It’s a definite time and resource suck to bury-unbury-rebury every time we need access.
Mesh is my choice control for the consistent SVB problems all over my area, though. They’re not quite as small and tough, so it doesn’t require sealing to the same degree. (I wouldn’t bother if we only had SB.)
Second Hitch: Pollinators can’t get in. That means hand pollinating more than seed stock. It’s also totally devastating for squash bees, so plant some melons for them.
It takes some attention and it can be laborious, but we can mitigate SB/SVB infestations. There aren’t many critters that prey on SB/SVB, so it’s all on us. Since the most effective methods require time and in some cases materials, we have to make some preparations so we can act immediately when they show up.