CHAPTER IX. 
THE THYSANOPTERA. 
The very small black flies which are such a source of annoyance 
to travellers in the summer-time, and which fly into our eyes and 
crawl over our faces during the prevalence of warm windy weather, 
principally belong to a kind of insect which is characterised by 
having very remarkable wings when in the adult condition. These 
insects exist by myriads, and there are several species of them ; 
The adult insect. The larva. 
(Magnified.) 
the incomplete metamorphosis of Thrips cerealium. 
and they are all exceedingly destructive to flowers, and especially 
to the bloom of cereal plants. The little black insects are to be 
seen on almost every flower, and they devour the delicate cellular 
tissue of the petals. Thrips cerealium is very destructive when 
it occurs in multitudes upon the wheat, barley, and oats, for it 
interferes with the proper nutrition of the grain, by nibbling the 
protecting envelopes and the tissue which connects it to the 
stalk. 
All the members of the genus Thrips — and they alone con- 
