πŸ› Backswimmer

Notonectidae spp. Β· Hemiptera: Notonectidae

Backswimmers are predatory aquatic bugs that swim upside down and can deliver a painful (but not medically serious) bite if handled. They show up in pools to hunt water boatmen β€” eliminating the water boatmen eliminates the backswimmers within days.

AquaticPool BugHemipteraPredatorBitesNotonectidae
πŸ›
Risk Level
Painful Bite β€” Otherwise Harmless
πŸ”¬
PestControlBasics Editorial Team
Reviewed by Derek Giordano Β· Updated 2026

πŸ” Identification

Small β€” 8–17mm long; elongated, somewhat tapered body; pale white or cream belly (which faces up while swimming); darker back (which faces down while swimming); long oar-like rear legs heavily fringed with hairs; large reddish or dark eyes prominent on a flattened head. The defining feature: backswimmers swim upside down, with the belly facing the sky. This is the easiest way to tell them apart from water boatmen, which swim right-side up. Backswimmers are often seen hanging just below the water surface, head-down, waiting to ambush prey.

🧬 Biology & Behavior

Backswimmers are predators β€” they are the lions of the small aquatic invertebrate world. They feed on tadpoles, small fish, mosquito larvae, water boatmen, and other small aquatic creatures. They grasp prey with their front legs and inject digestive saliva through a piercing beak (rostrum), then suck out the liquefied contents. This same beak can deliver a painful bite to a human who picks one up β€” comparable to a bee sting in intensity, though not allergic-reaction risk for most people. Like water boatmen, backswimmers carry an air supply against their body. Adults are strong fliers and are attracted to light at night. They lay eggs on submerged plant material and surfaces; nymphs are smaller wingless versions of adults.

⚠️ Damage & Health Risk

Backswimmer bites are painful β€” comparable to a bee sting β€” and can cause local redness, swelling, and itching for a few hours to a day. They are not medically serious for most people, but young children, the elderly, or anyone with insect-venom allergies should be careful. Bites usually happen when someone picks one up out of the pool by hand, scoops one up in a hand-skimmer net and then handles it, or accidentally grabs one while swimming. Backswimmers do not bite while you swim past them β€” they only bite when grabbed or pressed against skin.

πŸ”§ DIY Treatment

Backswimmers are in your pool because there is food (usually water boatmen, which are in turn there because of algae). Address the algae and the food chain collapses: shock the pool with chlorine, brush all surfaces, maintain free chlorine at 2–4 ppm and pH at 7.2–7.6. Within 5–7 days, the water boatmen leave (no food) and backswimmers follow (no prey). To remove existing backswimmers from the pool, use a long-handled pool skimmer net and tip them onto the deck or into a bucket β€” do not pick them up by hand. Run the pool filter the full recommended daily cycle. Turn off pool lights at night to reduce attraction of new arrivals.

πŸ‘· When to Call a Pro

Most backswimmer problems resolve with proper pool chemistry, but a pool service professional is helpful if the algae problem is persistent or if there is an underlying equipment issue (filter sand needs changing, pump not circulating properly, cyanuric acid too high). For pond or water feature backswimmer populations, a landscape or aquaculture professional can recommend stocking with fish that feed on backswimmer nymphs, or adjusting water chemistry and circulation to reduce prey populations.

❓ FAQ

Are backswimmer bites dangerous?
Backswimmer bites are painful β€” comparable to a bee sting β€” but not medically dangerous for most people. They cause local redness, swelling, and itching for a few hours to a day. They do not transmit disease and do not contain medically significant venom. People with severe insect allergies should be cautious as with any insect bite. Young children may find a bite quite painful and frightening. Wash the bite with soap and water and apply cold compress or hydrocortisone cream for symptom relief.
Why are backswimmers in my pool?
Backswimmers come to pools to hunt water boatmen, which arrive when the pool has algae. The presence of backswimmers indicates two issues: an algae problem in the pool (the underlying cause), and a water boatman population that the backswimmers are hunting. Fixing the algae fixes both. Backswimmers do not eat algae themselves β€” they are obligate predators.
DG
Derek Giordano
Certified Pest Control Operator Β· Former Business Owner
Derek ran his own pest control company in Florida for several years, servicing thousands of regular customers. All content is based on hands-on field experience and current EPA & university extension guidelines.

πŸ—ΊοΈ Geographic Range & Distribution

FactorDetails
U.S. RangeAll 50 states
States PresentFound commonly in 50 states; occasional in 0 additional states.
Regional DetailDistribution varies by sub-species and habitat. Consult your state wildlife agency or extension office for precise regional data.

πŸ“… Seasonal Timing Guide

Snake activity follows temperature and seasonal patterns. Knowing when snakes are most likely to be encountered helps with prevention and safety.

PeriodAction
SpringPool opening. Eliminate any algae present at startup. Inspect skimmer baskets for overwintering bugs.
SummerPeak activity. Watch for upside-down swimmers in the morning. Skim weekly. Maintain chemistry daily.
FallActivity decreases with temperature. Continue chemistry through closing to prevent overwintering populations.

πŸ’° Removal & Prevention Costs

Service TypeDIY CostProfessional Cost
Pool shock + chemistry$30–$80 in chemicals$100–$200 service call
Skimming / netting (DIY)$15–$40 for long netIncluded in routine service
Multi-visit algae remediation$50–$150 in materials$200–$500 over 2–3 visits

Prices vary by region, property type, and removal complexity.

❓ Common Questions About πŸ› Backswimmer

How do I tell backswimmers from water boatmen?
Backswimmers swim upside down with the belly (pale cream color) facing UP toward the sky. Water boatmen swim right-side up with the brown back facing UP. Backswimmers are slightly larger (8–17mm vs 5–11mm) and have more obvious reddish or dark eyes. The swimming orientation is the most reliable single difference β€” if it's upside down, it's a backswimmer, and you should not pick it up by hand.
Can I swim while backswimmers are in the pool?
Yes β€” backswimmers do not bite swimmers passing through the water. They only bite when grabbed, picked up, pressed against skin, or trapped in clothing. Most swimmers can ignore them safely. Use caution with young children who might try to catch them. Skim them out periodically with a long-handled net (without handling them) to keep their numbers down while the underlying algae problem is being addressed.
How long until backswimmers leave my pool?
Once you've eliminated the algae and water boatmen, backswimmers typically leave within 3–7 days because their food source is gone. They are strong fliers and will move to other water bodies with prey. Existing backswimmers can be netted out during the cleanup. Do not handle them β€” use a long pool skimmer and tip them out onto the deck or into a sealed bucket.
Will pesticide work against backswimmers?
No β€” and you should never add pesticide to swimming pool water. Most pesticides have poor efficacy against aquatic Hemiptera anyway, and the safety risks to swimmers make it inappropriate. Eliminating the algae through proper pool chemistry and equipment operation is the only safe and effective approach. The whole food chain (algae β†’ water boatmen β†’ backswimmers) collapses when you address the base of it.
🔗 Related Pests
πŸ› Water Boatman🦟 MosquitoπŸͺ² Giant Water Bug
Compare similar species to confirm your identification. → Use our ID Flowchart
πŸ“š Sources: EPA Pool Disinfection Guidance Β· CDC Healthy Swimming
Published: May 11, 2026 Β· Updated: May 11, 2026

When DIY education is more valuable than DIY treatment

Many homeowners default to attempting treatment before fully understanding the pest's biology, the product's mechanism, or the local pressure context β€” and the time spent on premature treatment frequently exceeds what reading and learning would have cost. The high-leverage education investments: extension service publications for any pest causing recurring problems (free, locally-specific, written by entomologists), the EPA pesticide product label for any product being considered (free, legally-binding, contains far more information than the marketing copy), the regional integrated pest management center publications (free, organized by pest, includes the IPM hierarchy of interventions), and (where appropriate) a single consultation with a licensed pest management professional for diagnosis-only without commitment to ongoing service. Two hours of focused reading before starting treatment typically changes the approach to better-matched products, correct life-stage timing, and accurate identification β€” producing better outcomes than buying a more expensive product at retail.

Pest pressure as a property value signal β€” and how to address it before listing

Pest issues directly affect property valuation in several documented ways: termite damage is a standard inspection finding that can derail closings or require significant credits; rodent activity in attics and crawlspaces flags during inspections and creates buyer concerns about hidden damage; visible cockroach or bedbug activity raises the question of what else has been neglected. Sellers who address pest issues before listing β€” ideally with documentation of treatment and a clean follow-up inspection β€” preserve more value than those who try to negotiate around buyer-discovered issues. The investment is typically modest relative to the price impact: a pre-listing inspection by a licensed pest control company runs a few hundred dollars in most markets, and resolving common findings (rodent exclusion, ant treatment, wasp nest removal) is rarely a significant expense. The value preservation comes from removing inspection findings as negotiation leverage, not from any single repair.

Integrated pest management for households: the practical hierarchy

Integrated pest management (IPM) is a structured approach to pest control developed for agricultural and commercial settings that translates well to residential use. The hierarchy: prevention first (sanitation, exclusion, habitat modification to make conditions unfavorable for pests), monitoring second (sticky monitors, visual inspection, identifying pests at low population before infestation establishes), targeted intervention third (using the least disruptive effective method against an identified pest in an identified location), and broad chemical treatment last (when targeted approaches have failed or aren't feasible). The hierarchy matters because higher-level interventions are durable and address root causes, while lower-level chemical interventions address symptoms and require repeat application. Most residential pest control reverses this hierarchy β€” chemical treatment first, sometimes prevention later β€” and produces the predictable consequence of recurring problems. Households that adopt the IPM hierarchy (often without using the term) generally describe spending less time and money on pest issues over years even though specific incidents might take more thought to address than spray-and-forget approaches.

How structural moisture issues drive pest problems most homeowners miss

A surprising fraction of pest problems are downstream of moisture issues that go uncorrected because they don't produce obvious damage. Subterranean termites require moist soil contact; correcting drainage and downspouts often reduces termite pressure more than any chemical treatment. Carpenter ants nest in damp or previously-damp wood; the colony moves in only after moisture has softened the substrate. Drain flies, fungus gnats, and springtails are all moisture-driven and resolve when the moisture source resolves. Mold mites and booklice indicate humidity that exceeds about 70%, often in unventilated bathrooms or basements. Even rodent activity correlates with moisture: rodents need accessible water and follow water-supply intrusions to bring themselves into structures. The diagnostic question worth asking on any chronic pest problem: is something wet that shouldn't be? Common offenders are clogged gutters, downspouts that drain near the foundation rather than away from it, condensate lines from HVAC systems and water heaters, slow plumbing leaks under sinks, sweating cold-water pipes in unconditioned spaces, and crawlspaces without adequate vapor barriers. Fixing the underlying moisture issue typically yields permanent improvement that chemical treatment alone cannot match.

Choosing a pest control company: questions worth asking

Pest control companies vary substantially in approach, training, and pricing, and the questions to ask before signing a contract often aren't the obvious ones. Worth asking: what's the technician's training and certification (state pest control certification is the floor; advanced training in IPM, structural inspection, or specific pest specialties is meaningful additional credentialing); what does the service include beyond visiting and spraying (inspection, monitoring, exclusion recommendations, follow-up scheduling); what guarantees apply if pests return between visits; what's the protocol for hard-to-resolve issues (some companies escalate to senior technicians or supervisors; others repeat the same approach); what active ingredients are used and whether the company will use specific products on request (homeowners with chemical sensitivities, pollinator gardens, or other concerns may want specific products); and what's the contract structure (per-visit, annual, multi-year). Worth less than expected: brand recognition and advertising spend (large national chains and small local operators both produce excellent and mediocre service); 'green' or 'organic' labels (which mean different things to different companies and often don't correspond to specific product or practice differences); price alone (typical pricing variance is modest, and the floor of cheap options often includes poor service).

Finding regional pest data sources worth trusting

The quality of pest information available to homeowners varies enormously by source, and finding the reliable sources for your specific region is a one-time investment that pays off across years of pest management decisions. Cooperative extension services associated with land grant universities in each state are usually the highest-quality regional resource, producing fact sheets, identification guides, and treatment recommendations specifically calibrated to local conditions, pest species, and regulatory environments. State department of agriculture pest fact sheets are typically similar in quality and orientation. Local pest control company blog content varies in quality but can be useful when produced by experienced practitioners writing about their actual work rather than generic SEO content. National pest control sites tend to be less useful for the specific reason that they average across regions and don't address the conditions you're actually facing. Bookmarking two or three high-quality regional resources at the outset, and consulting them before making significant pest management decisions, raises the average quality of your decisions dramatically without much ongoing effort.

Pest control warranties: reading the fine print before signing

Pest control warranties are not standardized, and the differences between contracts that look superficially similar can be enormous. Termite warranties in particular vary across at least three significant dimensions: whether they cover retreatment only or also include damage repair, whether the damage coverage is capped or unlimited, and whether the warranty is transferable to subsequent owners. A retreatment-only warranty on a property with significant termite pressure is much weaker than a damage-inclusive warranty, and the difference matters most precisely in the situations where the warranty is most likely to be needed. General pest control service agreements often have similar gradations β€” some include unlimited callbacks during the service period, some include a fixed number, and some charge for any visit outside the regular schedule. Before signing, the question to ask is not whether the contract has a warranty, but exactly what the warranty covers, what triggers a callback at no charge, and what the renewal terms are. Companies rarely volunteer this clearly; reading the document carefully and asking specific questions is on the homeowner.

Understanding pest forecast reports and what they signal

Pest forecast reports β€” issued by some state agricultural agencies, cooperative extension services, and commercial pest control companies β€” are an underutilized resource for homeowners who want to anticipate rather than react to seasonal pest activity. These reports typically combine historical pest data, current weather conditions, and growing degree day calculations to predict when specific pests will emerge or peak in specific regions. A tick forecast for an upcoming spring season, a mosquito pressure forecast after a wet winter, a termite swarm prediction for a specific week in the Southeast β€” these aren't speculation but reasonably calibrated predictions based on biological timing. For homeowners, the value is in scheduling preventive treatment and personal protection to match the predicted high-pressure windows rather than reacting after problems have established. Subscribing to a regional pest newsletter from a cooperative extension service or state agriculture department is free or low cost and produces these forecasts during relevant seasons. The information is dramatically more actionable than generic pest control content because it's calibrated to your specific region and current conditions.

πŸ—ΊοΈ US Distribution β€” Backswimmer

Common Occasional Not Present
States Present
50
Occasional
0
Primary Region
All 50 states
πŸ“Š Source: University extension services, USDA, CDC vector data, and published herpetological surveys.