Despite the advantages of complete metamorphosis, some insects can reproduce without metamorphosis. The phenomena of paedogenesis, or reproduction by immature stages is described for a number species scattered among insect orders.
Mycophila speyeri is a fungus gnat and pest of mushrooms. Mushrooms are typically short lived but provide substantial resource to insect that can reproduce rapidly. Mycophila speyeri does not need to undergo metamorphosis to reproduce. Larvae can produce clones by parthenogenesis to rapidly increase the population. The larvae can produce eggs that hatch and offspring develop within the hemocoel of the mother. The offspring consume the mother’s tissue, then chew and exit hole in the cuticle. The mother dies and is replaced by multiple clones. This adaptation allows Mycophila speyeri to reproduce much more rapidly.