Insects on Elm and Willow. 1 1 5 



wasps feed readily off the honey-dew excreted by this species of 

 aphis, and also that bees totally disregarded it. The flow of honey- 

 dew produced by this species is very copious and does much damage 

 to the trees and those beneath. It is not at all unusual for willows 

 and osiers to be killed outright by it. 



The effect of the punctures of these plant lice is to leave distinct 

 brown scars in stripes. This plant louse is also known as the 

 Aphis salUjna, Walker, other synonyms being Aphis salicis, Curtis, 

 Aphis viminalis, Boyer de Fonscolombe, and Lachnus viminalis. 

 Passerine. The wingless viviparous female is dark yellowish-bro^^Ti 

 to greyish-bro\^^l ; the antennne red at the base, black at the tips, 

 and there are two dark spots on the thorax. The abdomen is much 

 rounded and in the centre is a curious horn-like projection ; the 

 cornicles are large and short and there are five to six rows of large 

 black spots on it. The legs are deep brown, rather long and hauy. 

 In length they are about 0*16 of an inch. The pupa is much like 

 the larva, but rather longer and with bright brown wing cases, and 

 the dorsal tubercle is very large. 



The winged female is quite a large insect, 4 to 5 mm. in length, of 

 a dull brown colour with darker marks, the abdomen being spotted 

 with black, one large spot placed centrally ; this spot apparently is 

 the representative of the tubercle seen in the wingless female ; the 

 short cornicles are almost conical. The long wings always seem to 

 be carried horizontally when the insect is at rest ; the stigma is long, 

 nan'ow and black ; the insertion and cubitus orange-yellow. The 

 legs are long, the tibiae yellowish-red, the two-jointed tarsi deep 

 brown. 



As this is certainly a very harmful species steps should be taken 

 to destroy them by washing the willows with paraffin emulsion. 



This species is very common in some districts on willows and 

 osiers. They congregate in masses often half a foot in length and an 

 inch or more wide ; they are usually grouped side by side with their 

 heads pointing downwards. When disturbed these sedentary insects 

 l)ecome most active, yet do not leave their abode ; they throw their 

 long hind legs up and wave them about in an erratic manner, \^dth 

 the probable intention of frightening off the enemy, especially hymen - 

 opterous parasites. The effect of this species on the trees is very 

 strange. Some osiers observed this year were killed by them, whilst 

 others close to only presented a yellow-leafed appearance ; some shed 

 their leaves, others recovered in a few weeks. Cameron records a case 

 where this Lachnus swarmed in such numbers at Carshalton that 

 trees thirty to forty feet high had been killed by their poisonous 



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