Bug lookalikes
Almost nobody arrives asking what a spider is called. They arrive asking whether the one in front of them is the dangerous one. These pages take the pairs that genuinely get mixed up and give you the character that separates them.
13 comparisons, each built from two full records and checked against a reference source.
Where one of them matters
- Brown Recluse vs House SpiderLoxosceles reclusa vs Kukulcania hibernalisOne is dangerous
- Wolf Spider vs Brown RecluseHogna carolinensis vs Loxosceles reclusaOne is dangerous
- Black Widow vs False WidowLatrodectus mactans vs Steatoda grossaOne is dangerous
- Black Widow vs Brown WidowLatrodectus mactans vs Latrodectus geometricusOne is dangerous
- Brown Recluse vs Cellar SpiderLoxosceles reclusa vs Pholcus phalangioidesOne is dangerous
- Bed Bug vs TickCimex lectularius vs Ixodes scapularisOne is dangerous
Where neither can hurt you
- Hummingbird Moth vs White-lined SphinxHemaris thysbe vs Hyles lineataBoth harmless
- Polyphemus Moth vs Cecropia MothAntheraea polyphemus vs Hyalophora cecropiaBoth harmless
- Ladybug vs Asian Lady BeetleCoccinella septempunctata vs Harmonia axyridisOne can bite
- Carpenter Bee vs BumblebeeXylocopa virginica vs Bombus impatiensBoth harmless
- Wasp vs HornetPolistes fuscatus vs Dolichovespula maculataOne can bite
- Woodlouse vs Pill BugArmadillidium vulgare vs Oniscus asellusBoth harmless
- Flea vs Bed BugCtenocephalides felis vs Cimex lectulariusOne can bite
Why misidentification goes wrong the way it does
Testing identification against a set of photographs weighted towards dangerous species turned up a consistent pattern: almost every genuinely bad answer was not a near miss. It was a medically significant animal placed in an entirely wrong group — a widow called an orb weaver, a recluse called a funnel weaver — before any reasoning about danger could begin.
That is worth knowing because it changes what you should check. Once you have decided what kind of animal you are looking at, everything downstream inherits that decision, including the reassuring parts. Settle the group first, and be willing to be wrong about it.
- Count the legs before anything else. Eight is a spider, six is an insect.
- Eye arrangement separates more dangerous species from harmless ones than colour or markings ever will — and it is the thing a phone photo usually cannot resolve.
- Range rules out more than appearance does. A great many “brown recluse” reports come from states where the species does not occur at all.
- Where you found it is evidence. A spider hanging in a ceiling corner and a spider in a stored box are rarely the same kind of animal.
Common questions
Why not just use the identifier?
Use it — it is on the front page and it will give you an answer in a few seconds. These pages exist for the cases where the answer needs checking, or where the photograph genuinely cannot settle it and you want to know what to look at yourself.
What if my photo cannot settle it?
Every comparison here has a section for exactly that, because it is a common outcome rather than a failure. The short version: do not resolve an ambiguity towards the harmless option just because it is the more comfortable one.
How are the pairs chosen?
From the corpus itself. Every species record lists the species it is genuinely mistaken for, and that has to be reciprocal — if A is confused with B, B is confused with A, and the build fails otherwise. Comparisons are written for the pairs people actually search for, not generated for every link in the graph.