PLANT BUGS, APHIDES, AND SCALE. 233 



of the short cornicles. The garden seats on the open 

 lawn are also sprinkled with the same spots." 



That the aphides also cause transformations and 

 distortions of parts of plants, resembling galls, some- 

 times termed pseudo-galls, will be shown when we 

 come to write of galls and gall insects. 



A casual observation of a colony of these insects 

 will prove that they are not all alike, some being 

 winged and others not; more minute investigation 

 will reveal other and less evident differences. 



The males are either winged, or without wings, the 

 former being the most common. In this sex the 

 abdomen is smaller, and the colour usually brighter. 

 The females are also winged, or wingless in some 

 allied genera, but in the true aphides those females 

 which deposit eggs are uniformly without wings. Late 

 in the season winged females bring forth their young 

 alive, as well as some without wings. Hence we have 

 wingless males and winged males, wingless oviparous 

 females and, late in the year, both winged and wing- 

 less females, which bring forth their young alive. 



The multiplication of aphides is enormous ; some 

 species probably are confined to one brood, while 

 others reach to twenty, or, it is stated, to as many as 

 ninety. Latreille says one female during summer will 

 produce young at the rate of about twenty-five a day. 

 Reaumur calculates that one aphis may be the mother 

 of the enormous number of 5,904,900,000 individuals 

 during the month or six weeks of her existence. Pro- 

 fessor Huxley has made a calculation which affords 

 an approximate idea of what these immense numbers 

 mean. Assuming that an aphis weighs as little as one- 



