PARASITES THAT ABE FREE WHEN OLD. 171 



insects, show their cruelty in a different manner ; they 

 live in the bodies of the larvae of Cecidomyas which are 

 lodged in, the rolled leaves of the Salix, and suck the 

 blood of their victims. 



Other insects, known by the name of Meldidese, adopt 

 a different plan. Their larvae have been long known by 

 the name of bee-lice ; but they had not been recognized 

 in the perfect state, as the larvae did not resemble their 

 parents. 



These insects undergo four different moults before 

 they become nymphs, and at each moult their appear- 

 ance is completely changed. It may be easily under- 

 stood that it was long before these little beings were 

 recognized behind their masks. 



This is the manner in which they ravage our flower- 

 beds. While they still wear the dress of larvae, they cling 

 to certain female hymenoptera which they know very 

 well; and being fully assured that the door would be 

 shut in their face if they' presented themselves openly, 

 they enter, on their neighbour's back, the galleries where, 

 their housekeeping is carried on, and at the instant that 

 the female host lays an egg in v a cell of honey, the young 

 Meloe glides in with it, and allows itself to be shut in. 

 During this time it continues its metamorphosis, lying 

 in a lake of honey ; it devours it all at its ease, caring 

 nothing for the provision laid up for the hymenoptera 

 which introduced it. It is a brigand who, having 

 secreted himself in the carriage of a rich neighbour, 

 introduces himself on his shoulders into his children's 

 bed-chamber, assassinates them, and grows fat on the 

 provisions destined for his victims. 



" The Sitatis, the Meloe, and apparently other Melo- 



