Two insects on the documented list for this borderland region actually feed on parsnip foliage: grasshoppers and thrips. Grasshopper nymphs chew ragged notches into the leafy tops once they hatch from overwintered eggs, and thrips rasp the same leaves almost as soon as seedlings have anything to eat. Neither touches the root directly, and the rest of what’s documented here belongs to trees, orchards, or wasp nests, not a vegetable bed.
Which pests attack parsnip in Saskatchewan
Montana State University Extension, Urban IPM, and NDSU Extension together document ten insects for the prairie region bordering Saskatchewan to the south: apple maggot, boxelder bug, brown marmorated stink bug, Colorado potato beetle, corn earworm, emerald ash borer, grasshoppers, miller moths, social wasps, thrips, and yellowheaded spruce sawfly. That’s the full list sourced for this territory, and it isn’t padded with anything beyond it.
Most of that list has no business near a parsnip row. Apple maggot lays its eggs in apples and hawthorn fruit, not in root-vegetable leaves. Emerald ash borer only develops inside ash trees. Yellowheaded spruce sawfly feeds exclusively on spruce needles. Boxelder bug clusters on boxelder and maple seed pods and rarely bothers a vegetable garden at all. Colorado potato beetle specializes on the nightshade family (potato, eggplant, tomato), and parsnip belongs to the carrot family instead, a group whose leaf chemistry keeps out most single-family specialists. Corn earworm and brown marmorated stink bug both target fruiting crops (corn ears, tomato fruit, beans, peppers) and orchard fruit, so a plant grown for its taproot and its leaves gives them little reason to stop and feed. Social wasps are predators and scavengers that chew wood fiber for their nests; they don’t eat garden foliage. Miller moths are the migrating adult stage of the army cutworm, and adults in that stage don’t feed on plants at all, they’re mostly a nuisance for swarming around porch lights in late summer.
That leaves grasshoppers and thrips as the only species on this sourced list that behave as general feeders on garden greens, parsnip tops included. Neither is a root-crop specialist; both are opportunists that move onto whatever leafy growth is available once their numbers build.
When each one shows up, and what it does first
Parsnip goes into the ground as seed, not as a transplant, sown two to three weeks before the mean last spring frost of May 18 for the Saskatoon area. Germination is slow, 14 to 21 days before the first true leaves break the soil, according to Utah State University Extension. Nothing lands on the crop before that foliage exists, which sets the earliest point either pest can start.
Thrips show up almost as soon as those first true leaves are up, because they feed on tissue as thin as a seedling leaf. The first sign is a silvery or bronzed streaking along the leaf surface, sometimes with fine stippled dots where feeding has scraped the tissue.
Grasshoppers run on a slower clock. Their eggs overwinter in the soil, and Saskatoon’s coldest month averages a nightly minimum near -20.7°C (-5.3°F), cold enough that shallow egg pods often don’t make it through, while better-insulated ones do. Nymphs hatch as the soil warms in the weeks following the last frost, and the first visible sign is small nymphs chewing ragged notches along the leaf margins rather than the fine stippling thrips leave behind. Feeding intensifies through the warmest, driest stretch of the frost-free season and keeps going until the mean first fall frost of September 18 slows the insects down. Given that parsnip needs 100 to 120 days from seeding to reach harvest size, grasshopper pressure is often heaviest right around the point the roots are sizing up, not at the start of the season.
Telling the damage apart from everything else
A parsnip patch that looks off isn’t always dealing with an insect. Forked, branched roots are the classic false alarm here, and they have two separate possible causes on this crop: heavy or stony ground that splits the taproot as it grows, and overwatering, which encourages shallow lateral roots instead of one straight one. Neither has anything to do with grasshoppers or thrips, and the two causes shouldn’t be lumped together since the fix for one (working the soil deeper, or sowing on a bed built up over deep sandy soil) does nothing for the other (cutting back on watering frequency).
| Symptom | Possible cause | What tells it apart |
|---|---|---|
| Silvery or bronzed streaking on leaves | Thrips feeding | Fine stippled scraping visible with a hand lens, worse on new growth |
| Ragged notches at leaf edges | Grasshopper nymphs or adults | Chewed margins rather than surface scraping, often with visible insects nearby |
| Yellowing, uniform leaf color loss | Nutrient deficiency or drought stress | No chewing or scraping marks; affects whole plants evenly rather than individual leaves |
| Forked or split taproot | Heavy/stony soil or overwatering | No leaf damage above ground; root itself shows the split, not a bite or scrape |
None of this replaces an actual look at the plant. A local extension office or a certified crop advisor can confirm what’s causing a specific symptom in a specific garden, which matters more than guessing from a description alone.
What actually works here, and what is a waste of time
A floating row cover set down at seeding time, before germination even starts, does more for this crop than most other options. Parsnip is harvested for its root, so it doesn’t need pollinator access the way a fruiting vegetable does, and the cover can stay on for the entire frost-free stretch without costing any yield. That timing matters because the frost-free window here (May 18 to September 18) leaves barely more room than the 100 to 120 days parsnip needs to mature, so any early setback from feeding damage has little slack to recover in.
Spraying after damage is already visible tends to waste time. Thrips hide inside folded new growth where a surface treatment doesn’t reach them well, and grasshoppers keep moving in from field edges and roadside vegetation, so knocking back one wave doesn’t stop the next from arriving. Treating without a confirmed identification also risks killing off beneficial insects for no real gain. Clearing garden debris and mowing grassy borders near the bed removes some grasshopper egg-laying sites, which helps more over a season than any single treatment applied once damage shows up.
Where to check this for your own county
The documentation behind this page comes from Montana State University Extension, Urban IPM, and NDSU Extension, the two land-grant services covering the growing conditions just south of the Saskatchewan border. Saskatchewan doesn’t have its own line in this particular record, so what’s listed here is a regional picture drawn from neighboring territory, not a province-wide survey of what’s actually in Saskatchewan gardens.
Pest presence shifts inside a single province just as much as it does across a border. A garden near Saskatoon faces different pressure than one near Prince Albert to the north or Estevan to the south, since soil, wind exposure, and how close a yard sits to open grassland all change how many grasshoppers or thrips show up in a given year. Before treating anything, the useful next step is getting the insect actually identified by a local agricultural office or a certified crop advisor who knows the specific district, rather than relying on a regional list to say what’s in one particular garden.
Common questions
Does parsnip attract carrot rust fly in Saskatchewan?
That insect isn’t part of the documented list sourced for this territory. Montana State University Extension, Urban IPM, and NDSU Extension don’t name it here, so rather than assume it’s present, confirm with a local agricultural office if root tunneling or dark scarring shows up on harvested parsnip.
Why do parsnip roots fork instead of growing straight?
Two separate things can cause it: heavy or stony soil that splits the taproot as it pushes down, or overwatering, which pushes the plant toward shallow lateral roots instead of one straight one. Neither is insect damage, and each has a different fix.
When should parsnip be sown to avoid the worst grasshopper pressure?
Sowing two to three weeks before the mean last frost of May 18 gets seedlings established before nymphs hatch in large numbers, though pressure from grasshoppers tends to peak later in the season regardless, closer to when roots are sizing up toward the 100 to 120 day mark.
Do parsnips actually need a hard frost to taste good?
Yes, according to Utah State University Extension, the sweetening comes from several weeks of exposure to frosty weather, which converts stored starch to sugar. That comes from actual cold exposure, not from the surrounding hardiness zone, so leaving roots in the ground into the cooler weeks after the first fall frost improves flavor rather than harvesting early.