From Black Mesa: Wiki

A render of the Hivehand as it appears in Black Mesa.

Overview

The Hivehand is a Xenian weapon that fires insect-like creatures which home in on their targets and capable to bounce over walls. As its name indicates, the hivehand is supposed to be a small nest for those insects but its function as a weapon remains unknown. The ammunition for the hivehand regenerates constantly but maximum ready to fire insectoid darts is limited to 8 [1].

It is most commonly referred to as the "hornet-gun".

Primary Function

Fire slow, but semi-homing hornets that leave trails from the Hivehand. These will bounce off of walls and cannot damage breakable physics props.

Hornets can track a specific target by aiming the cross-hair at it then fire the primary function (in fact this is also the only way to target friendly NPCs) [2].

Secondary Function

Fire off a rapid barrage of non-homing hornets that leave trails in a straight path, which do not bounce off of walls but can damage breakable physics props or move them.

Media

Trivia

• The Hivehand is wielded by Alien Grunts, however you cannot take one off of their dead bodies. A Hivehand must be found alone to acquire it.
• Unlike HL1, automated sentry turrets won't fire on hornets [3].