HEMIPTERA. 



20- 



Fig. 172. — Eggs and 

 nymph of Corythuca 

 arcuata, (From the 

 Author's Report for 

 1879.) 



of different species of Cratagus. The infested leaves have a brown 

 and sunburnt appearance. All stages were found together. The 

 adult is represented much enlarged by Fig. 171. In Fig. 172 the 

 eggs and immature form are shown. The eggs are 

 smooth, whitish, glistening, semitransparent, and 

 ovoid in shape. Their average length is 3 mm. 

 (0.12 in.). They are deposited on their broad end, 

 and seem to be somewhat inserted into the sub- 

 stance of the leaf ; they are covered completely 

 by a brown, sticky substance, which hardens soon 

 after oviposition. It adheres so firmly to the egg, 

 especially to the upper portion, that it is impos- 

 sible to remove it without crushing the egg. 

 At its upper end this covering of the egg is squarely 

 truncate, giving the whole mass the appearance 

 of a frustum of a cone with a porous lid. From 

 the funnel-shaped summit the young insect makes its exit. The eggs 

 are usually laid, in groups of from ten to thirty, along both sides of 

 some prominent leaf vein. They bear a much greater resemblance 

 to certain forms of fungi, notably the genus PJiowa, and to certain 

 young Homopterous galls, than they do to eggs of any sort. 



The immature insect is of the same dirty brown color as the sub- 

 stance covering the egg, and but little darker than the withering 

 leaf. It is of a broad, flat, oval shape, and spines seem to project 

 from almost every portion of its body. It looks under the micro- 

 scope more like a lobe of prickly cactus than anything else I can 

 think of. The cast-off skins stick to the leaf, and give it the appear- 

 ance of being much more seriously infested than it really is. 



The dead leaves under the bushes during the winter have been 

 often found to contain the living and healthy eggs of the Tingis ; 

 but the customary method of hibernation is in the adult state alone. 

 This form can be found during the winter under the loose bark of 

 the tree, and under sticks and stones on the ground. These insects 

 can be destroyed by strong alkaline washes or by kerosene emul- 

 sions. But it is probable that if the leaves and rubbish underneath 

 the trees are destroyed, either every fall or every spring, a necessity 

 for remedies will not arise. 



Sub-Family II. — Piksmiwk. 



This division includes a single aberrant genus, Piestna, of which 

 but few species are known. Here the scutellum is not covered ; the 



