304 Habits of the Greenhouse White Fhf 



leaves below, inviting the prolific growth of fungi which ruin plants 

 used for ornamental purposes. The adults prefer the young leaves 

 for oviposition, and gradually ascend as the plant grows. Hence there 

 will be green eggs on the newest leaves; a little lower, brown eggs; 

 lower still the first stage larvae will predominate ; below these the 

 second stage larvae; and so on. Finally, on the oldest leaves, adults 

 will be emerging. Occasionally eggs are laid on the stalks, flowers, and 

 upper leaf surface ; but they are generally laid in circles on the under-side, 

 if the leaves are not very hairy and the insects undisturbed. The 

 circle of eggs is made in a very ingenious way. The insect inserts its 

 stylets into the leaf tissue and, using that point as centre and its body 

 as radius, revolves as each egg is deposited. Hairiness of the leaves 

 prevents this turning and the eggs are then scattered. The eggs are 

 stalked, the stalk being short and partly embedded in the tissue of the 

 leaf and arranged perpendicular to the leaf surface. They are green 



Fig. 1. Egg. Fig. 2. Circle of eggs. 



when first deposited and covered with the wax ("meal") produced by 

 the adult, as also is the portion of leaf in the vicinity of the eggs. The 

 circles of eggs are generally incomplete, with a diametej- of about 

 1-5 mm., and I have not seen more than 15 eggs in one ring. (Length of 

 stalk, 0-02 mm., total length of egg, 0-24 mm., greatest breadth, 0-70 mm.) 

 After two to four days (according to temperature, as I kept the 

 humidity fairly constant) the eggs begin to darken in colour, turning 

 from the original yellowish green to brown and finally to black. When 

 nearing the time of hatching, which is about ten days after deposition, 

 the meal drops off, leaving the egg smooth and shiny. The larva is 

 visible inside, and its two eyes appear as bright red spots shining through 

 the egg case near its free end. When about to hatch, the egg moves 

 slightly from side to side, and two surfaces may now be distinguished : 

 a convex, corresponding to the dorsal, and a concave, corresponding 

 to the ventral surface of the larva. Hatching occurs ten to thirteen 

 days after deposition. A crack appears near the free end of the egg on 



