120 DESTRUCTIVE INSECTS OF VICTORIA : 



" Extreme cold does not affect the ova of insects much. 

 M. Girard points out that the eggs of the silkworm will 

 bear a cold of 25 C. in their passage over the mountains 

 of Japan, and that the caterpillars may be frozen, " so as 

 to ring like metal on a marble slab," and yet after a slow 

 thawing they will come to life and feed like others. The 

 fond hopes that cold would destroy the hybernating egg 

 of phylloxera cannot therefore be realized. 



" Balbiani states that the winged females deposit their 

 pseudova amidst the down on the under-side of the leaf; 

 and Riley says that this is the common habit of the 

 American species. The insect, however, will drop them 

 on the bark, or stem, or indeed almost anywhere. 



" THE MALE AND FEMALE. These perfect sexes were, 

 I believe, first discovered by M. Lichtenstein, and after- 

 wards by Professor Riley in America. They are exceed- 

 ingly small, and have no true mouth parts. A small 

 eminence is the sole representative of the buccal organs. 



" THE APTEROUS (WINGLESS) MALE. This minute insect 

 is pale ferruginous yellow and cycloid ; flat, testudinate, 

 with a very small head furnished with small black eyes. 

 Thorax proper there is none ; the abdomen is coarsely 

 ringed and corrugated ; legs short, with obtuse tarsi and 

 very minute claws. The male is so small that it may be 

 easily overlooked. 



. " THE SEXED FEMALE is much of the colour of the male, 

 but is larger. The abdominal cavity contains a single 

 egg, which is the true ovum. The female delivers herself 

 of it about the fourth day after she is hatched, and this 

 without any real necessity of concourse with the male. 

 Whether such eggs are barren it does not appear (see 

 Riley, Eighth Report, p. 159). The true ovum is larger 

 than all the preceding pseudova. It is yellow at first, 

 but soon afterwards it becomes olive in colour, with a 

 rough exterior. Its survival through the winter in the 

 crevices of the bark has been substantiated by Balbiani 

 and M. Lichtenstein, and there is no doubt that the foun- 

 dation (the first form issuing from the fecundated egg) is 

 the produce of the same, just as with other aphides. 



