This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
虵 combines 虫 (insect/reptile) with 也, which likely contributes the sound. The exact historical development is uncertain.
The insect radical 虫 beside 也 suggests a creeping creature, but without a clear meaning, picture a mysterious bug that defies easy description.
For ジャ, imagine a jar full of strange insects: jar -> ジャ, and the 虫 radical hints at the bugs inside.