Page:Insects - Their Ways and Means of Living.djvu/404

 having the same essential structure as that of the horse&shy;fly (Fig. 170 A).

The house fly has no piercing organs; it subsists en&shy;tirely on a liquid diet. The food liquid enters the aper- ture between the labella, and is drawn up to the true



mouth through the food canal in the labium between the labrum and the hypopharynx. The fly, however, is not dependent on natural liquids; it can dissolve soluble sub&shy;stances, such as sugar, by means of its saliva. The saliva is ejected from the tip of the hypopharynx, and probably spreads over the food through the channels of the labial lobes. These same channels, perhaps, also collect the food solution and convey it to the labellar aperture.