April, '10] DAVIS: ILLINOIS IXSECTS 181 



with hydrocyanic acid gas or tobacco is practiced, it seldom becomes 

 troublesome. 



The squash-bug {Anasa tristis DeG.) was found destructive in a 

 few isolated localities, and in every instance the injured vines were 

 near an out-building or other desirable hibernating quarters. More 

 often the injury was to young cucumber plants in cold frames. 



The fickle midge (Sciara inconstans Fitch) is one of the most 

 destructive hothouse cucumber pests in northern Illinois. The mag- 

 gots attack the roots and stem of the plant, gnawing the tissue and 

 eating into it. Affected plants may be recognized by a characteristic 

 wilting, and by their slow growth, and unless treated they will soon 

 die. Never have I found appreciable injury except where fresh 

 manure was used. The susceptibility of various varieties is well 

 shown in the photographs. Two varieties, Davis Perfect and a com- 

 mon white spine, were grow^n in the same range, the cultivation, 

 planting, manuring, etc., being identical. The Davis Perfect, a 

 cross between a white spine and English, was scarcely injured, and 

 had large healthy foliage, while the common white spine was practi- 

 cally ruined. The use of a soaponified creosote preparation, applied 

 at the base of the plant, proved of value, but further experiments 

 should be made with it before it can be recommended as a certain 

 remedy. Nicotine extract and "lemon oil" also proved beneficial. 

 The use of old rather than fresh manure is certainly most com- 

 mendable. 



The greenhouse white-fly (Aleurodcs vaporariorum West.) and the 

 red spider (Tetranychus himaculatus Harv.) are always pests of cu- 

 cumbers under glass in this state. As is well known, the former 

 can be controlled by the proper use of hydrocyanic acid gas, but the 

 red spider, after once getting a good start, is not so easily dealt with. 

 Nothing that we have tried has proven satisfactory. 



Horse-radish w^as injured in certain localities by the horse-radish 

 flea-beetle (Phyllotreta annoracm Koch^). 



Greenhouse lettuce was badly attacked by the variegated cutworm 

 (Peridroma saucia Hbn.), and the European lettuce plant-louse 

 {Macrosiphum lactucce Kalt. ?). By poisoning the lettuce leaves and 

 laying them on the bed before setting out the plants, injury by the 

 cutworms was, in most cases, prevented. The plant-lice were easily 

 controlled by the use of tobacco or hydrocyanic acid gas fumigation. 



The onion-maggot {Phorhia cepetorum Meade), although doing 

 much injury in several places, was not nearly so numerous as in 

 years previous. 



^Determined by C. A. Hart. 



