4 LIFE-HISTORY AND METAMORPHOSES. 



consequently there is a great deal of overlapping 

 eggs, larvae, and adult insects occurring at the same 

 time. 



A peculiar habit noticeable among many Coccids is 

 that they fix themselves along the midrib and larger 

 nerve bundles of the leaves, where they would 

 naturally get the greatest flow of sap. Mr. F. W. 

 Burbidge, of the Botanic Gardens, Dublin, kindly 

 called my attention to this fact, and in the same com- 

 munication gives a note on a remarkable habit in 

 Gryptococcus fagi, which seems to show that other 

 species of Fagus are distasteful to it. I give Mr. 

 Burbidge's own words : " You may have noticed a 

 curious fact ; the two common kinds of weeping beech 

 are grafted by nurserymen on the common beech as a 

 stock. Here we have a tree, the stock of whicli is 

 infected by the Coccus, but it does not infest the weep- 

 ing beech scion. I showed our plant to a gentleman 

 who has a very fine weeping beech, also grafted ns 

 above, and he tells me it is just the same with his tree 

 stock infected, scion free from the insect pest " (in. 

 lit., Oct. 26th, 1900). 



THE OVUM. 



A Coccid deposits its eggs but once during its life, 

 the period varying according to the habit of the species. 

 The time occupied in oviposition is usually of com- 

 paratively short duration, but in a few instances it is 

 more prolonged, and may extend over several weeks. 

 Eggs laid in spring and summer hatch before winter, 

 while those laid in the autumn do not hatch until the 

 following spring. The number laid by individual 

 females varies considerably in the different species. 

 So far as my experience goes, the minimum is reached 

 in the sub-family Diaspindz, which in Mytilaspis pomorum 

 gives, approximately, an average of about twenty-five, 

 the maximum being probably reached in certain species 



