אַ֤ךְ אֶת־זֶה֙ תֹּֽאכְל֔וּ מִכֹּל֙ שֶׁ֣רֶץ הָע֔וֹף הַהֹלֵ֖ךְ עַל־אַרְבַּ֑ע אֲשֶׁר־לא [ל֤וֹ] כְרָעַ֙יִם֙ מִמַּ֣עַל לְרַגְלָ֔יו לְנַתֵּ֥ר בָּהֵ֖ן עַל־הָאָֽרֶץ׃
Yet these may ye eat of all winged swarming things that go upon all fours, which have jointed legs above their feet, wherewith to leap upon the earth;
Sefer HaMitzvot
That is that He commanded us to check for the signs of locusts as well. And [the signs] are written in the Torah - "all [...] that have, above their feet, jointed legs" (Leviticus 11:21). And the content of this commandment is like that which we explained in the commandment before this; and the verse about it is His saying, "Of these you may eat the following - locusts" (Leviticus 11:22). And the laws of this commandment have already been explained in Tractate Chullin. (See Parashat Shemini; Mishneh Torah, Forbidden Foods 1.)
Sefer HaChinukh
The commandment of checking the signs of grasshoppers: To check the signs of grasshoppers - and these are the signs that are written in the Torah, "that has jointed legs above its feet, etc." (Leviticus 11:21) - as it is stated, "this you may eat from all the winged swarming things." And the content of its root is like with the other species.