December, '17] HawleY: hop redbug 551 



Adults may often be found in September but eventually die. There 

 is no evidence that they survive the winter. 



Natural Enemies 



Predators. — The Pentatomid, Apeteticus maculiventris Say, is pre- 

 daceous in both the nj^mphal and adult forms on the immature stages 

 of the hop redbug. Eggs and nymphs of this form are common on 

 the hop in July and August. 



One of the Nabidce, Reduviolus subcoleoptratus Kirby, which is 

 present on many plants near the hop yards, has been found feeding 

 on the nymphs of the hop redbug. 



A predaceous red mite {Trombidium sp.) has been observed on sev- 

 eral nymphs. 



The adults, Paracalocoris haivleyi, of this species have been found 

 feeding on nymphs of their own kind. Nymphs have also been found 

 feeding on the pupa of Ania limbata (Geometridae), the larva of Lysia 

 cognataria (Geometridae), the larva of Hypena humuli (Noctuidae), 

 and the pupa of Malacosoma americana (Lasiocampidae). 



Control 



In 1915 it was decided to test a tobacco extract spray on the hop 

 redbug. To this end nicotine sulphate (Black leaf 40), 1 pint to 100 

 gallons of water, with 6 pounds of soap, was applied on July 17. The 

 material apparently killed at once. However, as fifty-six live nymphs 

 were found on six sprayed hills on July 19 another spray was applied. 

 This time Black leaf 40, 1 pint to 100 gallons of water with 4 pounds 

 of soap was used. On July 20, six hills had sixteen dead and eleven 

 live nymphs present, but on July 21 no dead nymphs could be found. 

 This is due to the fact that the nymphs, after the spray material dries, 

 drop off. The following experiment shows that whenever nymphs are 

 reached they are killed. On July 19, when field experiments were 

 carried on, forty sprayed specimens were placed in a laboratory cage. 

 None revived. Thirty specimens sprayed with an atomizer were all 

 killed when the same solution as used in the field was apphed. 



Since nicotine sulphate, f pint to 100 gallons of water with 4 pounds 

 of soap, will control the hop aphis {Phordon humuli Schrank), the writer 

 tried it to see the effect on the hop redbug. Leaves with redbugs from 

 vines sprayed in the field were taken into the laboratory. Six of 

 fifteen specimens were alive the following day. Seven of thirty red- 

 bugs sprayed in the laboratory were alive twenty-four hours later. 

 When the bug became attached to the glass dish by means of the solu- 

 tion, it was invariably killed — otherwise it often recovered. To pre- 

 vent sticking, filter paper was plabed in the bottom of the dish and the 



