Mantispinae have the most specialized larval development among all mantidflies studied to date ( the life history of the Drepanicinae remains unknown ) : their campodeiform larvae seek out female spiders or their egg sacs which they then enter ; the scarabaeiform larvae then feed on the spider eggs , draining egg contents through a piercing\/sucking tube formed by modified mandibles and maxillae , pupating in the egg sac .
Larvae of the subfamily Mantispinae seek out female spiders or their egg sacs which they then enter ; the scarab-like larvae then feed on the spider eggs , draining egg contents through a piercing\/sucking tube .