Grappling And the Giant Scorpion

[Blackwolf]

The PHB Pg.195 says when you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack; a grapple. If you are able to make multiple attacks with the attack action, this attack replaces one of them. The target of your grapple must be no more than one size larger you and must be within reach.
The Giant Scorpion MM Pg.327 Claw Attack which it has two of, reach 5 ft. one target when hit is auto grappled (Specific case). Can you Make an Attack of Opportunity a Grapple attack? per standard Rules? and can the Giant Scorpion or another creature like get a opportunity grapple attack?

[LordEntrails]

I dont think a normal creature can make a grapple as an opportunity attack. But I would reread all the rules before deciding.

A giant scorpion can certainly make a claw attack as it OA, which then also grapples.

[Blackwolf]

So if another creature were to have a similar ability are a weapon that would give are allow auto grapple when hitting with an attack, could then grapple as part of a Opportunity attack such as a Man Catcher,Whip or a Net?

[Zacchaeus]

A grapple requires an attack action. An attack of opportunity does not allow an attack action. Ergo you can’t grapple with an opportunity attack.

Various beasts may of course overrule this.

[Blackwolf]

Net PHB pg. 148 Special weapon Rule:A Large or smaller creature hit by a net is restrained until it is freed. A net has no effect on creatures that are formless, or creatures that are Huge or larger. A creature can use its action to make a DC 10 Strength check, freeing itself or another creature within its reach on a success. Dealing 5 slashing damage to the net (AC 10) also frees the creature without harming it, ending the effect and destroying the net. When you use an action, bonus action, or reaction to attack with a net, you can make only one attack regardless of .he number of attacks you can normally make.
Grappled Condition: a grappled creature's speed becomes 0. it can't benefit from any bonus to its speed.
Restrained Condition: a restrained creature's speed becomes 0. and it can't benefit from any bonus to its speed. the creature has disadvantage on dexterity saving throws. Attack rolls against the creature have advantage, and the creatures attack roll have disadvantage.