Sign In Get Started
Preposition after verb

Infest with or infest by?

Infest is usually used in passive structures. Both infested with and infested by are possible, but they express different ideas.

Quick answer

Which preposition is correct with infest?

Use infested with to describe what fills or overruns a place. Use infested by to name the creature or agent causing the infestation. Both are standard, but with is more common in everyday descriptions.

The basement was infested with cockroaches.
The grain stores were infested by rats.
Several rooms were infested with ants.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
infested with + pests

Describing what fills a place

Use infested with when focusing on the insects, animals, or harmful things present in large numbers.

The kitchen was infested with flies.
The trees were infested with beetles.
2
infested by + creature

Naming the source of the infestation

Use infested by when emphasizing the agent causing the infestation.

The warehouse was infested by mice.
The fields were infested by locusts.
3
infest + place

Using infest as an active verb

In active sentences, infest takes a direct object without a preposition.

Cockroaches infested the building.
Mosquitoes infested the swamp.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
infested with
The attic was infested with bats.
Focuses on what is present in the place.
infested by
The attic was infested by bats.
Focuses more on the creatures as the source of the problem.
infest + object
Termites infested the old house.
Active verb with a direct object and no preposition.

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Using a preposition after active infest

Infest directly takes an object in active clauses.

✕ Insects infested in the garden. ✓ Insects infested the garden.

Confusing with and by

With usually describes what fills the place, while by emphasizes the agent.

✕ The room was infested by dirt. ✓ The room was infested with dirt.

Using infest for temporary presence

Infest suggests a large, harmful, or uncontrollable presence.

✕ A few birds infested the park. ✓ A few birds were in the park.

Quick practice

Choose the expression that matches the intended meaning.

1. The apartment was ___ cockroaches.
2. The crops were infested ___ locusts.
3. Choose the correct sentence.

Check your sentence in context

Paste the complete sentence below. Linguix checks the preposition together with grammar, spelling, punctuation, and style.

Free to try · No signup required

Frequently asked questions

Is infested with more common than infested by?

Yes. Infested with is the usual everyday pattern when describing pests or harmful things in a place.

Can infest be used in active sentences?

Yes. You can say that insects infest a building or weeds infest a garden.

Can I use infest for non-living things?

Sometimes. Writers may use it for harmful things such as corruption, rumours, or crime in a figurative sense.

identify-with-by-in-as, for "ignore by" or "ignore in"? illuminate by, with, at, for or in? "illustrate by" or "illustrate in"? "imagine for", "imagine by" or "imagine in"? imbue with, in, by or onto? immigrate to, from, in, with or into? impair by, for, in, because or throughout? "impart to", "impart in" or "impart by"? "impeach by" or "impeach for"? "impinge on" or "impinge upon"? "implement in" or "implement by"?

Write with confidence in Linguix

Create a free account to check complete texts, apply suggestions, and save your documents.

Create a free account