284 OBSERVATIONS ON INSECTS. 



LETTUCE BLIGHT. 



IN the summer of 1844, the entire crop of lettuces 

 in my garden were destroyed by a blight at the roots, 

 arising from the attacks of a small species of Erio- 

 soma.* This insect had never shewn itself there in 

 any previous year to my knowledge. In this in- 

 stance, all the young lettuces, from six to nine 

 inches high, were observed with their lower leaves 

 flaccid, and flat on the earth, as if parched from 

 drought : the older ones, which had been tied up for 

 blanching, were some of them completely dead, and 

 brown at the heart others dying. No insects were 

 observed upon the plants above ground ; but, on pull- 

 ing them up, the fibres of the roots were found 

 thickly matted with a glutinous cottony substance, 

 amongst which were crawling hundreds of the larvae 

 and pupae. This was on the 28th of August, and at 

 that time no perfect insects were as yet visible. 

 The larvae were of all sizes, some very small, and ap- 

 parently but just hatched : here and there imbedded 

 in the cottony substance were the eggs themselves. 

 The former were rather active in their movements, of 

 a green colour, with six rather short feet, the hinder 

 pair not longer than the others ; the antennae also 

 short, of six joints. The pupae had rudiments of 



* One of the genera belonging to the family of Aphidx, or 

 plant-lice, but distinguished from Aphis by its short filiform 

 antennae, tomentose body, and abdomen destitute of horns or 

 tubercles towards the apex. 



