170 



AGRICULTURAL COLLEGE BULLETINS. 



distributed, but when present in any considerable numbers they do great 

 damage. Every lady who keeps house plants knows this full well. 



As is well known, plant lice on outside vegetation pass the winter as little, 

 dark oblong eggs, usually fastened to the buds. With the warm days of 

 spring these eggs hatch, and so rapidly do the lice increase that soon, by the 

 middle or last of May, the lice are often counted by millions and billions. 

 Sometimes they start off in great numbers in spring. I have seen apple trees 

 in April when hardly a bud could be found that was not the home of lice, 

 and I have counted as many as fifty lice on a single bud. Surely there is 

 not much promise in such a bud. 



Another feature which is very characteristic of plant lice, is their sudden 

 disappearance. Our cherry trees may be black with them in May, and within 

 a month the lice may be so used up that v/e can hardly find a specimen. The 

 same is true of nearly all the species that infest our out-door plants and trees. 

 This welcome riddance is due to insect enemies of the 

 lice. A syphus fly (fig 2) maggot (fig 3), with a pointed 

 head just revels amidst the plant lice. This maggot 

 seems never satiated. It is hard to understand how so 

 small an insect can take so large a meal. The maggots 

 are constantly banqueting on the plump, juicy lice. The 

 lady bird beetles (fig. 4), especially the larva? or grubs 

 also do signal service in this same direction. Last year, 

 owing 1 think to the excessive drouth, plant lice were 

 very common. This gave the lady bird beetles a sy^us My. 



rich opportunity, and often we might see thousands of 

 the active grubs on a single tree. The sad feature in this 

 case was that many people, through ignorance, thought 

 that these insects were the real culprits, and so destroyed 

 them by the thousands. We have also found several species 

 of the Ichneumon family of the genus Aphidius, very min- 

 ute parasites, which destroy these lice by the thousands. 

 Thus it is that plant lice on out-door vegetation, though 

 they may threaten dire mischief early in the spring, 

 are almost vanquished before summer comes. 

 Occasionally a year like last year (1886), owing 

 probably to the excessive drouth, the plant lice 

 thrive out of proportion, and succeed in spite of 

 their enemies, when they do most serious injury. 

 Owing to this scourge, many an orchard which 

 promised bountifully in the spring of 1886 failed 

 almost utterly to bear good fruit. 



In some cases, as in the snow ball, the leaves roll up and protect the lice 

 from their eager foes, and thus these beautiful shrubs are likely to suffer 

 seriously each year, even if they are not wholly destroyed through the blight- 

 ing presence of plant lice. Other plants, like the white willow, are likely to 

 suffer seriously about one year in four. 



(Fig. 3.) 

 Maggot. 



(Fig. 4.) 

 Larva, pupa and beetle. 



KEMEDIES. 



I have found nothing so satisfactory in treating plant lice as the kerosene 

 and soap mixture. To make this I use one-fourth pound of hard soap, pre- 



