Tick.
There is only one way to spell "leash" (restrain, or a restraint for a dog).The similar words that are homophones are leech(blood-ducking insect) and leach (to wash out of).
Insect.
There is no actual "opposite" of an insect. However, the other insect-sized arthropods are the arachnids (spiders and scorpions).
They spell the word "tick" (a biting insect, or a clock sound).
That is the correct spelling of the insect, the silkworm.
The household insect pest is a "cockroach".
The word with that phonetic spelling is pacifier (a sucking implement for babies).
Insect is the correct spelling.
The insect is a cicada. (family includes the co-called 17-year locust)
If you are referring to the blood sucking creature, the correct spelling isleeches(or "leech" for just one).If you mean the sub-tropicalfruitfrom south-east Asia, the correct spelling islychees (or lychee for one).
The spelling of the flying insect name is the damselfly.
The correct spelling of the biting insect is mosquito.