Hemiptera plant. Phloem sap, which has a higher concentration of sugars and nitrogen, is under positive pressure unlike the more dilute xylem sap. Most of the Sternorrhyncha and a number of Auchenorrhynchan groups feed on phloem. Phloem feeding is common in the Fulgoromorpha, most Cicadellidae and in the Heteroptera. The Typhlocybine Cicadellids specialize in feeding on non-vascular mesophyll tissue of leaves, which is more nutritious than the leaf epidermis. Most Heteroptera also feed on mesophyll tissue where they are more likely to encounter defensive secondary plant metabolites which often leads to the evolution of host specificity. Obligate xylem feeding is a
Sugary drink tax third parties (MXC) and so want to consume at the unregulated market equilibrium to maximize their utility. This means that there is overconsumption of sugar and a welfare loss is created. The sugary drinks tax, a Pigovian tax, is a way to correct the negative externality by regulating the consumption of sugary drinks. Without a sugary drink tax, taxpayer money is used to pay for higher health care costs incurred from high consumption of sugar. Although this solution corrects the negative consumption externality, taxpayers that consume sugary drinks moderately and hence do not contribute to higher health care costs, still