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The gallon jug that settles the caterpillar problem for multiple seasons straight.

This is the concentrate built for anyone with a serious garden or multiple trees. The bottle holds 128 fluid ounces of liquid — 128 fluid ounces, versus 32 fluid ounces of the Bonide RTU — and since the label says to use just 1 to 4 ounces per gallon of water, a single jug goes a very long way. One buyer mentioned they “only had to spray 1 time and all caterpillars/worms gone” and expects the jug to last several growing seasons. You get protection from tomato worms, squash borers, and cabbage worms with this one big bottle.

Unlike ready-to-use sprays, you do have to mix this yourself with water in a pump or hose-end sprayer. But that trade-off buys you class-leading economy if you are protecting colecrops, squash vines, or an orchard. Reviewers also note bagworms dropping dead by the next morning when coverage is thorough — “go ALL the way around the tree and make sure you cover it well.” It contains nothing harmful to humans when used as directed — a relief for organic gardening. If you want to mix once and stop worrying about reordering mid-season, this jug is the obvious choice.

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The grab-and-spray bottle that killed caterpillars on basil overnight, per buyers.

This is the simplest entry into BT for caterpillars: a 32-fluid-ounce trigger-sprayer bottle with zero mixing. One owner reported it “killed green caterpillars on basil overnight; plant recovered and looks great after two weeks” — a typical fast result when you catch the infestation early. It controls cabbage loopers, hornworms, and tent caterpillars, and the label lists safe use on broccoli, cauliflower, kale, tomatoes, peppers, and melons. So you can spray and eat the same week.

The big difference from a concentrate is convenience. You do not need a separate sprayer or a measuring spoon. On the other hand, this 32-ounce ready-to-use gives you exactly 32 fluid ounces of coverage — the 16-ounce Monterey concentrate (Product 3) can be diluted to make far more total spray volume. For a small garden or a few container plants, that trade-off is worth it. Owners mention it “requires thorough spraying and reapplication after rain” and works best on small caterpillars. It is OMRI-listed-compatible and safe for honeybees, earthworms, and ladybugs once dry — no collateral damage to the beneficials in your garden.

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The small-yet-mighty concentrate that gives you control over mix strength.

A 16-fluid-ounce bottle sounds small, but this is a concentrate — you mix it with water at home, so it actually goes further than many ready-to-use sprays. The manufacturer says it is “easy to apply” — just stir it into a trigger spray bottle or pressure tank and go. One customer observed after spraying their tomatoes “following the directions on the bottle, two days later I found several caterpillars dead,” which matches the typical BT feeding-stop-to-death timeline. Monterey lists this for cabbage loopers, bagworm, gypsy moth, and elm spanworm — a broad range of leaf-eaters.

It is OMRI Listed for organic gardening and has no effect on honeybees, earthworms, or ladybugs when used as directed. Unlike some larger concentrates, the 16-ounce size is easy to store in a garden shed or garage shelf. It also comes bundled with a measuring spoon, which removes the guesswork from dilution — a small detail that new users appreciate. The flip side: you do need your own sprayer. And because BT breaks down in sunlight, one experienced reviewer advises mixing only what you need that evening and spraying at dusk to boost potency before UV (ultraviolet light from the sun) degrades it.

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The dry-powder option that a repeat buyer says keeps an acre of colecrops clean.

This is a different form factor — a 1-pound bag of dry powder that contains 54% Bacillus thuringiensis (meaning over half the powder is active bacteria). You mix it with water to create your own spray, and because it is a powder, it stores indefinitely without leaking or freezing. One buyer living in Louisiana said last year caterpillars stripped all the leaves from their blueberry bushes and rose bushes; after a few applications of Dipel Pro, they reported “no more caterpillers.” A separate reviewer who repeatedly purchases this product notes it “keeps my acre of colecrops clean of cabbage loopers” and calls it cheaper than buying liquid BT at the farm store. For a large grower, that price-to-value comparison matters.

It is OMRI listed and has “no time to harvest restrictions,” meaning you can spray right up to the day you pick. One important note from a reviewer: this is Bt kurstaki (BTk), not Bt israelensis (Bti) — do not buy it for fungus gnat control in houseplants. But for caterpillars, it is fast-acting and potent. The powder must be mixed in water and used with a sprayer, which makes it slightly less convenient than a ready-to-use liquid, but the concentrated 54% active ingredient means a little powder goes a long way. The bag is light at 1 lb, but you need to store it dry and keep it away from moisture.

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The hose-end sprayer that one buyer used to knock out bagworms on arborvitae in two sprays.

This Monterey concentrate comes with a hose-end sprayer attachment — you screw it onto your garden hose, turn the water on, and spray. It is a 32-ounce bottle (the same size as the Bonide RTU but a concentrate), so you do not need a separate pump sprayer. One user highlighted they “had bag worms on my Abrovitaes. 2 spraying and I can see that it’s working.” Another saw immediate results on cankerworms: “Applied as instructed and they killed them immediately. The cankerworms [ate] the leaves off both bushes and now they are growing back.” This makes it the most efficient pick for covering tall shade trees without refilling a hand-pump.

The Monterey B.t. is OMRI Listed and targets the same broad list as the 16-oz version: cabbage looper, bagworm, gypsy moth, elm spanworm, and more. Since it attaches to the hose, covering tall shade trees or entire rows of ornamentals is much faster than with a hand-pump sprayer. One buyer deducted a star because the spray pattern is not adjustable — the hose pressure dictates the force, which can be too strong for delicate plants. Bending the hose to reduce flow is a workaround, but it is a design gap to be aware of. The 32-ounce bottle weighs 2.46 pounds, while the 16-ounce version weighs 16 ounces. If you already have a hose, this is the most efficient way to cover cankerworms and tree pests without refilling a sprayer.