affecting the Potato-crops. 



105 



taming the larvae and pupae also, which resembled figs. 51 and 

 52. The potatoes were like old rotten cheese, and portions of 

 the outside were covered with slimy threads, which Mr. Graham 

 saw the larvae spin. He thinks they cause the ' scab ' in pota- 

 toes, but I saw not the least vestige of the insect on one variety of 

 my potatoes, which was very scabby. 



32. S. pulicaria ? Meigen* Hoff., is J a line long or upwards, 

 and is distinguished from the two foregoing species by its longer 

 antennae, which are equal in length to the rest of the body. " It 

 is black, with testaceous legs : the wings almost hyaline : balancers 

 brown." 



My specimens being as big again as Meigen's, with ochreous 

 balancers, I am doubtful if they be the S. pulicaria of that author. 

 I bred them in August, 1845, from a rotten potato. 



Another Dipterous insect was bred from the potatoes in less 

 quantities. It also belongs to the Family Tipulid^e, and the 

 Genus Scathopse. It appears to be Meigen's 



33. S. punctata.^ It is black and shining: the head is small ; 

 the eyes are kidney-shaped, with 3 little ocelli on the crown ; the 

 antennae are short, stout, cylindrical, and composed of 1 1 cup- 

 shaped joints: thorax elongated and somewhat compressed, with 

 a white dot on each side; scutel small and rough: abdomen broad, 

 oval, and depressed : wings ample, resting horizontally, transpa- 

 rent, and iridescent, with a black costal, subcostal, and basal 

 nervure, the 1st and 2nd united beyond the middle, and divided 

 near the base, by an oblique nervure ; there are also 4 other very 

 faint longitudinal nervures, the apical one forked, the anal one 

 waved : balancers yellowish : legs simple, longish, and rusty ; 

 extremity of thighs and shanks variegated with fuscous ; feet 

 brown, 5-jointed, terminated by a pair of minute claws. Length 

 1J line, expanse 3J lines. 



The larvae from which these flies proceed, live in various 

 putrid substances, and even in dung : they have also been bred 

 from the cocoons of silkworms, in all probability containing de- 

 composing caterpillars or rotten pupae ; they are from 2 lines to 

 nearly \ inch long, flat, and narrowed at both ends, of a dirty 

 greyish-yellow colour ; the head is brown and oval, with 2 short 

 feelers : the body is composed of 12 pubescent segments, the 1st 

 thoracic one with a prominent spiracle on each side, as well as 

 the penultimate, which with the apex is covered with radiating 

 bristles. The pupa is \\ line long : it is enclosed in the skin of 

 the larva, a little depressed, and yellowish brown : from the tho- 

 rax projects a branched spiracle, like a buck's horn, and the tail 



* Syst. Besch. Europ. zweif. Inseck., vol. i. p. 282, No. 12. 

 t Ibid., vol. i. p. 301, No. 4, and Curtis's Guide, Genus 1177, 3. 



