The California Dog's-head is even more beautiful than the southern species. It is remarkable for its pink and purple iridescence--a characteristic which is not common in the butterflies of the Yellow and the White Tribes. The silhouette of the Dog's-head is less perfect than in the more eastern species, and the yellow color tones are more tinged with orange. The female is strikingly different, the wings being plain pale yellowish buff marked only with a round blackish eye-spot near the middle of each front wing and the barest suggestion of a dark line around the extreme margin. =The Clouded Sulphur= _Eurymus philodice_ It is an interesting fact that the butterfly which one is most likely to find in fields and along roadsides during practically all the weeks of summer has seldom if ever been noted as a destructive insect. The Clouded Sulphur is probably the commonest species in its group. There may be times when the White Cabbage butterfly or other forms are more abundant, but the Clouded Sulphur retains its place season after season, with comparatively little noticeable variation in its numbers. This is doubtless an illustration of an insect which has established such relations with its food plants and its various insect and other enemies that it remains in a fairly stable equilibrium--an example of what is often called the balance of nature. The Clouded Sulphur is about the only medium-sized yellow butterfly generally found in the Northeastern states. The adults may be seen from spring until autumn. They lay eggs upon clover and other plants. These eggs hatch into small green caterpillars that feed upon the leaves and are protectively colored so they are comparatively seldom seen. When the food plant is disturbed they drop to the ground, crawling up again upon stems and leaves when the disturbance is over. These caterpillars moult several times during their growth. When full grown they find such shelter as they are able and each spins a silken web over part of the surface. It then fastens its hind legs into this web and later spins a loop near the front end of the body. It pushes itself beneath this loop and waits for several hours before the skin breaks open along the back and is gradually shuffled off revealing the chrysalis in position. A week or two later the fully developed butterfly emerges from the chrysalis. These yellow butterflies lend a distinctive charm to our summer landscapes. They are constantly to be seen fluttering from place to place, lightly visiting flowers of many kinds from which they suck the nectar, and gathering in great colonies by roadside pools where they seem to sip the moisture. There are many references to this insect in the writings of New England authors. It evidently was an especial favorite of James Russell Lowell who has often referred to it in passages like this: "Those old days when the balancing of a yellow butterfly over a thistle bloom was spiritual food and lodging for a whole forenoon."