APHIDID^E. 323 



''According to what has just been said, we have in the Chermes 

 cycle only three principal (chief or leading) forms viz. : 



1. The parthenogenetic (non-sexual or asexual) wingless form. 



2. The parthenogenetic (non-sexual or asexual) winged form. 



3. The sexual generation with male and female. 



" But in reality the number is increased, as each of these forms 

 varies more or less in the 3-4 moulting stages. Especially does the 

 appearance of the insect change between the first and the last stage 

 of the parthenogenetic winged form (migrans aluta)." 



The question of how to form a precise recognition of the different 

 species, and the various stages of the same species, is somewhat dif- 

 ficult to determine. It would be advisable to boil and stain the 

 respective mother Chermes, as found on different food-plants, and 

 compare their minute structure, such as chitin plates, wax glands, 

 antennae joints, legs, and so forth, together with the colour of the 

 eggs and general habits of the creatures. 



Second, as regards the so-called species, it would perhaps be well 

 to consider them separately in the usual way, both as to their relation 

 with other closely allied insects and the damage on different trees. 

 Hence they may now be considered in the ordinary manner of genus 

 and species. 



Genus Chermes. 



This genus is exclusively arboreal, and the respective species are 

 confined to conifers. They come near to the Coccidse or Scale-Insects 

 in point of anatomical structure, and nearer in general appearance of 

 damage than any other tribe in the whole family. Thus the snowy 

 appearance presented by the felt scale on beech, and the white fluffy 

 matter on the stem of silver fir and Weymouth pine, are to the naked 

 eye practically identical. The difference between the two families 

 can only be decided by microscopical examination, and in fact, 

 between the respective species of this genus, can only be decided 

 by the most careful microscopical examination. 



In structure the genus Chermes is characterised by the upper wing 

 having three oblique non-furcated veins, and the under wing a single 

 oblique vein. The antennae are normally five-jointed. The rostrum 

 is very short, being used exclusively as a feeding-organ, and not 

 specially for anchorage. The creature develops three or more long 



