genetic modification ideas

for the last few days I have been thinking about 

genetically modifying insects and/or crustaceans 

to make it unnecessary for them to molt 

so when a crustacean's body has grown

then it's hard shell become soft 

so that the body can expand 

and the soft shell expands too 

and then the soft shell becomes hard again 

this removes the potential risks of molting 

for both younger individuals and older individuals