THE CANADIAN ENTOMOLOGIST 345 



REMARKS ON LYGUS INVITUS SAY, WITH DE- 

 SCRIPTIONS OF A NEW SPECIES AND VARIETY 

 OF LYGUS. (HEMIPTERA MIRID^). 



BY HARRY H. KNIGHT, ITHACA, N. Y.* 



The writer, has spent considerable time during the past three 

 seasons making observations on the life history and food plants 

 of many species of Mirida and particularly in tlie genus Lygiis. 

 The writer is also concluding work on a monograph of the genus 

 Lygtis, but for the benefit of certain economic w^orkers interested 

 in the forms here considered this small contribution is published 

 in advance. 



In the past Lygns invitus Say has been the name generally 

 applied to the members of a small group of species, which on careful 

 study based upon distinctive structures furnished by the male 

 genital claspers, are readily and consistently separated. Thomas 

 Say described invitus in 1831 and in his usual style this early worker 

 brought out certain characters that wdll distinguish the species 

 from all others. After a careful study of some forty species of 

 Lygus, I wish to point out a distinctive combination of characters 

 mentioned by Say and not exhibited by any other form thus far 

 brought to my attention. The following is taken from the original 

 description: " C. invitus — Dark livid or blackish; beneath green 

 with a blackish lateral vitta." "Head . . . with an im- 

 pressed longitudinal line . . . scutel with a pale, obsolete 

 vitta, beyond the middle . . , beneath green, with a broad 

 lateral black vitta." 



After careful search for food plants I find that invitus breeds 

 only on the elm, preferring always the young, thrifty plants with 

 succulent shoots. The nymphs are pale greenish, hatching soon 

 after the leaves come out in the spring from eggs that were in- 

 serted in the twigs the previous July. One can scarcely dis- 

 tinguish the nymphs from those of the species described below 

 and which is well known as a pest on the pear. The nymphs 

 are, however, smaller and more slender than those of the false 



* Contribution from the Department of Entomology of Cornell University. 

 October. 1916 



