4 oo 



VII. 



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, princi- 

 pally 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 ; 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 tissues of the 



Figs. 381, 382. The Adult Insect and Larva of Tkrips trtetiliuMt (magnified). 



petals. TJirips cerfalium is very destructive when it occurs in multi- 

 tudes 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 constitute 

 the order now under consideration possess four very narrow mem- 

 branous wings, without any folds or network upon them, but furnished 

 and decorated with beautiful fringes upon the edges. These fringes 



