104 



HOP APHIS. 



Phorodon hwmdi Schr. 



Unaffected Hop Plant. — A spiay of liops, modeled in wax, representing the 

 plant as it appeai-s in vigorons growing condition and free from the attacks of its 

 l)rincipal enemy, the ho}) aphis. This is to call attention to the stronger foliage and 

 the more abundant and larger hojis pnxluced by plants from which the hop aphis 

 has been eradicated by the use of proper remedies. 



Affected Hop Plant. — A spray of hops, modeled in wax, representing the vine 

 as it appears when attacked by the hop aphis, showing the blackening and dis- 

 coloration of the leaves and the small and inferior hops, which are also discolored 

 and otherwise unsuitable for market. 



WiNTEE EctGs. — Enlarged model of the winter eggs, which are attached by the 

 sexual female to the terminal twigs of the plum, in crevices around the buds. 



Stem-Mother. — The stout female aphis shown in this enlarged model hatches 

 from the winter egg and is characterized by shorter legs and honey-tubes. It gives 

 birth, without the intervention of tlie male, to living young, of which three genera- 

 tions are produced on the plum trees, the last being winged and migrating to the hop. 



WiN(4ED Migrant. — This enlarged model represents the first winged generation, 

 the third produced on the plum. It instinctively flies to the hoj) plant and is the 

 progenitor of from five to twelve wingless generations of virgin females, which infest 

 the hop plants until autumn and are the sole forms which dejiredate on the hop. 

 In autumn the last generation again produces winged females which fly to the plum 

 trees. 



Hop-Affecting Stage. — This enlarged model represents the structure and ai)pear- 

 ance of the five to twelve wingless generations of virgin females which people the 

 hop plant until autumn. These are the progeny of the winged migrants and are the 

 sole forms which injure the hop. 



Return Migrant. — This eidarged model represents the last generation produced 

 on the hop, the winged migrant form which in September returns again to the plum 

 and gives birth to three or more young, which are the true sexual females, tlie first 

 perfect sexual females produced in the cycle uji to this point. 



Pupa of Return Migrant. — This model represents the pupal stage of the relnrn 

 migravt. The striking features aire the wing ])ads, which with another molt become 

 the ample flight organs seen in the model of the adult. 



True Sexual Female. — This enlarged model represents the generation born of the 

 return migrant, which never acquire wings and never leave the plum tree. Maturing 

 in a few days, according to the temperature, they are fertilized by the true winged 

 males which have been subsequently developed on the hops and have come from the 

 hop fields to the plum. Shortly after fertilization the winter eggs, like those with 

 which the cycle started, are deposited. 



Young Sexual Female. — This enlarged model represents the newly hatched stage 

 of the only perfectly developed sexual female produced in the life cycle of this 

 insect. 



Winged Male. — This enlarged model represents the first and only male genera- 

 tion produced in the life cycle of tiie hop aphis. This is developed in tlie autumn 

 and flies from the hop to the plum and fertilizes tlie true sexual females. 



CHINCH BUG. 



BUsKHs leKcopferus Say. 



The Eggs.— This enlarged model rej^resents the form of the egg and the terminal 

 cap. The eggs are three-hundredths of an inch long, the top being squarely docked 

 and surrounded by four round tubercles near the center. Color from pale whitish 

 to amber. 



First Larval St.vge. — This stage, represented enlarged in this model, differs from 

 the adult in being more elongate and in having two-jointed tarsi, the head broader 

 and more rounded and the joints of the body subequal. The prevailing color of the 

 whole body is red. 



Second Larval Stage. — After the first molt the form represented in this enlarged 

 model is assumed. The red })ecomes a brilliant vermilion and contrasts with the pale 

 band across the middle of tlie body, while the head and prothorax are dusky and 

 coriaceous. Two broad marks appear on the mesothorax and the second, fourth, 

 and fifth abdominal sutures, and one at the tip of the abdomen. 



Pupa. — The pupa shown in this enlarged model approaches still more nearly the 

 form of the adult, and is not unlike the last larval stage except in being darker ami 

 in the appearance of wing pads, which extend almost across the pale basal abdominal 

 joints. 



