Squash bugs (Anasa tristis) are a highly destructive pest that feeds on members of the Cucurbitaceae family, such as cucumbers, watermelons, zucchini, and squash plants.
These pests change slightly during their life cycle but are easy to spot. They often overwinter under boards, in vines, dead leaves, and even in buildings as shelters during their unmated cycle.
The red squash bugs lay eggs in the undersides of leaves and veins in clusters containing 20 to 40 individual eggs each through the mid-summer.
The eggs hatch into young nymphs measuring about ½” an inch long, with whitish-grey bodies that go through a total of five instar stages.
Adult squash bugs reach ⅝” inches long and have greyish-brown or dark brown bodies and black legs similar to stink bug but with an orange underside on their abdomens.
Squash bugs are sap drinkers, sucking the squash plant and draining its fluids with their piercing-sucking mouthparts, which can cause cucurbit leaves to dry, fall off, and attack the squash fruit itself.
You will also notice wilting, similar to the bacterial wilt that cucumber beetles carry when you have a squash bug infestation.
In addition, their feeding causes delayed plant growth, killed seedlings, and yellow spots that turn brown.
When threatened, they emit an unpleasant odor similar to that of stink bugs, making it even more frustrating to deal with an infestation.
Thankfully, there are effective, natural ways to deal with these pests to protect your vegetable, like squash, cucumbers, pumpkins, and other gourds in your organic garden.
Does Neem Oil Kill Squash Bugs?
Neem oil is one of the most effective all-natural, non-toxic remedies out there, along with diatomaceous earth (DE for short).
It can kill not only squash bugs but many other cucurbits threats as well.
How Neem Oil Works
Neem oil is derived from the seeds of Azadirachta indica and contains five active chemicals.
The most important of these is the active ingredient Azadirachtin, which has a chemical composition similar to the hormones of many insect species.
When ingested, Azadirachtin will cause squash bug nymphs to lose their appetite and can stunt or stall progression through the growth stages.
Related: Learn more about How Neem Oil Works On Plant Pests.
In adult squash bugs, neem oil has the added effect of causing infertility.
100% percent cold-pressed raw neem oil is the direct result of crushing the seeds, with neem cakes being a useful byproduct.
When the Azadirachtin is extracted from raw neem oil to use in other pesticides, the result is clarified hydrophobic neem oil.
The clarified oil comes in concentrations of .5 to 3% percent and serves as a topical pesticide, clogging the airways of insects and causing them to suffocate.
When applying the natural pesticide neem oil, you need to add it to emulsified water, which is just a teaspoon of safe or natural soap such as pure Castile or Dawn dish liquid soap blended into each gallon of water.
This soapy water has the surface tension broken, making it possible for the neem oil to be mixed in.
Using Neem Soil Soak
One of the primary tactics against plant-piercing bugs is a neem soil soak. The best time to apply this is early morning or late at night when there is less pollinator activity like bees.
Mix two tablespoons of raw neem oil per gallon of water and pour 2 to 4 cups of the mixture over the roots of the affected plant.
More on How To Apply Neem Oil To Soil
As the roots soak up the mixture, the Azadirachtin mingles into the plant’s sap, turning it into a systemic insecticide.
Any squash bug which attempts to consume the sap will also consume the Azadirachtin, halting a squash bug infestation and slowly killing it off.
This method won’t affect the eggs, but it can last up to 22 days and won’t harm predatory insects such as parasitic wasps or lady beetles, which will be free to help eliminate the infestation.
Reapply every three weeks until the infestation is gone or monthly as a preventative.
Using Neem Foliar Spray
Neem Oil foliar sprays work differently from soil drenches and have a very short lifespan.
However, they can help reduce squash bug infestation quickly by suffocating nymphs and adults, reducing the overall squash bug population.
To make the foliar spray, add four teaspoons of clarified neem oil per gallon of emulsified water and pour it into a spray bottle.
Coat the entire plant, getting the underside of cucurbit leaves as you go and ensuring a good amount gets onto any squash bugs you encounter.
The spray dissipates after 45 minutes to an hour without leaving any residue, so it won’t harm beneficial insects or pollinators if sprayed around dusk or dawn.
You will need to reapply the foliar spray every two days for two weeks or until the infestation is gone.
Afterward, you may choose to do a preventative spray every 14 days up until the day before harvest.
A Note on Squash Bug Eggs
The eggs are the one part of the squash bug life cycle that is resistant to neem.
Extra soapy water can make the neem oil stick longer, killing the nymphs as they hatch, but this can also harm beneficial insects.
Remember, the eggs laid by females are yellowish to bronze and are oval shaped.
To treat the eggs, you may choose to wipe them off of the leaves simply, or you can leave them for natural predators, knowing the nymphs will be vulnerable to neem once they’ve hatched.
Another simple removal trick is picking egg masses or simply scraping them off the undersides of the leaves with a butter knife, letting them fall onto the ground.
Moreover, early detection of nymphs is crucial since adult bugs are more difficult to kill.
It’s also best to remove plant debris or plant matter that can provide overwintering sites to them during the growing season.
Can You Also Use Neem Oil for Squash Vine Borer Infestations?
Neem oil treatments have a similar effect on squash vine borers and vine borer eggs.
Related: Controlling Stink Bugs with Neem Oil
As with squash bugs, the squash borer (Melittia satyriniformis), in its larval form, is highly destructive to a cucurbit plant.
Vine borer larvae burrow into the vine, feasting on the innards while blocking the flow of nutrients.
Neem soil soaks have some degree of effectiveness but is most potent when the larva burrows into the hollow vine.
The adult moth is attracted to the color yellow, laying up to 150 eggs on the host plant, but thankfully doesn’t directly harm the plant itself.
Note that neem oil can also treat powdery mildew, which sometimes appears on plants that have been attacked by sap-drinking insects.