noun
aphid; plant louse
The primary modern meaning. A small sap-sucking insect. Usually written in kana.
バラの葉にアブラムシがたくさんついている。
There are a lot of aphids on the rose leaves.
アブラムシは植物の汁を吸う害虫
Aphids are pests that suck plant sap.
noun
Dialectal (Kansai-ben) meaning. In standard Japanese, ゴキブリ is used.
See also: ゴキブリ
関西ではアブラムシと言えばゴキブリのことだ。
In Kansai, 'aburamushi' means cockroach.
noun
Rare term. Refers to the bat species Pipistrellus abramus. More commonly called 油蝙蝠 (あぶらこうもり).
See also: 油蝙蝠
「油虫」は稀にアブラコウモリを指すこともある。
'Aburamushi' can rarely refer to the Japanese house bat.
noun
Figurative use, likening a person to a pest that clings and takes advantage. Not a common modern insult.
彼はいつもたかってくる油虫のようなやつだ。
He's a parasite who always mooches off others.
noun
looker (in red-light district)
Archaic. A visitor to a red-light district who only looks and does not spend money.
江戸時代、遊郭で遊ばずに見るだけの客を油虫と呼んだ。
In the Edo period, a customer who only looked around the pleasure quarters without spending money was called 'aburamushi'.