APPENDIX. 41 



According- to the latest researches Phryganea grandis 1 never con- 

 tains food in its alimentary canal, but only air, although it contains 

 the latter in such quantities that the anterior end of the chylific 

 ventricle is dilated by it. 



III. STREPSIPTERA. 



The larva requires for its development a rather shorter time than 

 that which is necessary for the grub of the bee into the body of which 

 it has bored. The pupa stage lasts eight to ten days. The male, 

 which flies about in a most impetuous manner, lives only two to 

 three hours, while the female lives for some days. Possibly the 

 pairing does not take place until the female is two io three days old. 

 The viviparous female seems to produce young only once in a life- 

 time, and then dies : it is at present uncertain whether she also pro- 

 duces young parthenogenetically (cf. Siebold, ' Ueber Paedogenesis 

 der Strepsipteren, ' Zeitschr. f. Wissensch. Zool., Band. XX, 1870). 



IV. HEMIPTERA. 



Aphis. Bonnet (' Observations sur les Pucerons,' Paris, 1 745) had 

 a parthenogenetic female of Aphis euonymi in his possession for 

 thirty-one days, from its birth, during which time it brought forth 

 ninety-five larvae. Gleichen kept a parthenogenetic female of 

 Aphis mali fifteen to twenty-three days. 



Aphis foliorum ulmi. The mother of a colony which leaves 

 the egg in May is 2"' long at the end of July : it therefore lives 

 for at least two and a half months (De Geer, ' Abhandlungen zur 

 Geschichte. der Insekten,' 1783, III. p. 53). 



Phylloxera vastatrix. The males are merely ephemeral sexual 

 organisms, they have no proboscis and no alimentary canal, and 

 die immediately after fertilizing the female. 



Pemphigus terebinthi. The male as well as the female sexual in- 

 dividuals are wingless and without a proboscis ; they cannot take 

 food and consequently live but a short time, far shorter than the 

 parthenogenetic females of the same species (Derbes, ' Note sur les 

 aphides du pistachier terebinthe,' Ann. des sci. nat., Tom. XVII, 

 1872). 



Cicada. In spite of the numerous and laborious descriptions of 



1 Imhof, ' Beitrage zur Anatomie der Perla maxima? Inaug. Diss., Aarau, 1881. 



