Barbei — Life-History of a New Family of Beetles. 187 



Certain individuals of the paedogenetic form, however, do not 

 develop embryos, and of these many die apparently barren, but 

 others void, through the vulva, instead of several migratory or 

 ' caraboid " young, a single large, soft, oval egg winch adheres 

 to the side of the mother and hatches in eight or ten days into 

 a first stage larva utterly unlike the previous forms and which 

 much resemble a weevil larva in appearance. This larva puts 

 its head into the vnlva of its mother and feeds on the contents 

 of her body, growing rapidly and looking like the larva of a 

 hymenopterous parasite. When full fed it changes into another 

 form of larva having short, stumpy, three-jointed legs, and 

 later pupates. It now appears that only male imagoes develop 

 out of this metrophagous larva from the uni-oviparous paedo- 

 genetic form, and that only female imagoes develop din it 

 from pupae out of the cerambicoid larvae. 



According to common knowledge it is expected that the 

 female after mating will lay eggs (few in number and of large 

 size as in other paedogenetic species) which will hatch into first 

 stage larvae (probably different from either of the other first 

 stage larvae that have been mentioned), and that these will 

 moult into feeding larvae that may or may not he the feeding 

 larvae preceding the paedogenetic form. The whole may be 

 better understood by combining the known and the unknown 

 forms in a diagram. (See accompanying plate.) 



It is believed that the observations on which the above 

 scheme is based were on individuals behaving in their normal 

 and regular manner; that males only are developed from the 

 mother-devouring curculioid larva hatching from the single egg 

 of the oviparous paedogenetic form, and that the amount of 

 animal food taken by the young caraboid larvae in feeding after 

 birth upon the body of their viviparous paedogenetic mother 

 may govern the development of females or the oviparous 

 paedogenetic form instead of viviparous paedogenetic indi- 

 viduals. Other factors, however, must of course play important 

 parts and it is quite possible that a change of the wood to a 

 dryer, warmer condition may force a majority of the developing 

 brood of feeding larvae out as females. 



The provision against inbreeding before alluded to as the 

 series of interpolated larval stages of the male should be better 

 explained. The cerambicoid larva, to produce a female, simply 



