INSECTS. 95 



which live under the leaves, causing them by their punctures to 

 become thickened, to curl, or form hollows beneath, and corre- 

 sponding crispy and reddish swellings above, and finally to perish 

 and drop off prematurely. The depredations of these lice is one 

 of the causes, if not the only cause of the peculiar malady affecting 

 the peach-tree in the early part of summer, and called the blight. 

 Plant-lice produce a blight of apple-trees occasionally. 



The injuries occasioned by plant-lice are much greater than would 

 at first be expected from the small size and extreme weakness of 

 the insects ; but these make up by their numbers what they want 

 in strength individually, and thus become formidable enemies to 

 vegetation. By their punctures, and the quantity of sap which they 

 draw from the leaves, the functions of these important organs are 

 deranged or interrupted, the food of the plant, which is there elab- 

 orated to nourish the stem and mature the fruit, is withdrawn, 

 before it can reach its proper destination, or is contaminated and 

 left in a state unfitted to supply the wants of vegetation. Plants 

 are differently affected by these insects. Some wither and cease 

 to grow, their leaves and stems put on a sickly appearance, and 

 soon die from exhaustion. Others, though not killed, are greatly 

 impeded in their growth, and their tender parts, which are attacked, 

 become stunted, curled, or warped. The punctures of these lice 

 seem to poison some plants, and affect others in a most singular 

 manner, producing warts or swellings, which are sometimes solid 

 and sometimes hollow, and contain in their interior a swarm of lice, 

 the descendants of a single individual, whose punctures were the 

 original cause of the tumor. 



When trees are infected, scrape off all the rough bark of the in- 

 fected trees, and make them perfectly clean and smooth early in 

 the spring ; then rub the trunk and limbs with a stiff brush wet 

 with a solution of potash as hereafter recommended for the destruc- 

 tion of bark- lice ; after which remove the sods and earth around 

 the bottom of the trunk, and with the scraper, brush, and alkaline 

 liquor cleanse that part as far as the roots can conveniently be un- 

 covered. The earth and sods should immediately be carried away, 

 fresh loam should be placed around the roots, and all cracks and 

 wounds should be filled with grafting cement or clay mortar. 

 Small limbs and extremities of branches, if infected, and beyond 

 reach of the applications, should be cut off and burned. 



This insect is mischievous and destructive to well grown and 

 riper. mg grass plants ; its minute character has allowed it to escape 



