A HISTORY OF ESSEX 



lie dormant through the winter and produce the generations of the suc- 

 ceeding year. Some of the Essex gardeners seem to labour under strange 

 delusions about Aphides, for they will tell you that like divers other 

 noxious insects they come over with the east wind in the spring, and 

 that they are especially abundant ' after we have had a heavy fall of 

 honey-dew.' They do not seem to know that the sweet clammy sub- 

 stance called honeydew is a secretion from the Aphides themselves, and 

 that it is because they are already abundant that the ' fall ' is heavy. The 

 species that infest the beech, birch, cabbage, currant, dock, elm, honey- 

 suckle, lime and rose are too well known examples of the tribe, but to 

 name all its food plants we should require a second botanical section. 



Mr. Fitch has noticed that Aphis asteris, from the situation it affects 

 in the Essex salt marshes, must be covered by the tide eight hours out of 

 the twenty-four ; and though as a rule the fully developed forms dis- 

 appear in the autumn, some of them may in mild seasons be met with 

 much later in the year. Siphonophora lactucce for instance was abundant 

 among the inner folded leaves of lettuce at Colchester during December, 

 1900, and continued to flourish till its food was destroyed by the severe 

 frosts that followed. Some authors say that all the individuals of the 

 early broods are wingless, but this is certainly not the case invariably, 

 for winged specimens of some species have been common at Colchester 

 during the present spring (1901). Existing in such enormous numbers, 

 and carrying on their operations on such an extensive scale, Aphides are 

 generally formidable enemies to contend against ; small greenhouse plants 

 can be easily freed from them, but large trees and crops that cover exten- 

 sive areas do not so readily lend themselves to successful treatment, and 

 most of the remedies recommended are costly and useless, and in apply- 

 ing them we are in danger of interfering with nature's remedies, which 

 are as a rule much more efficacious than ours. 



No tribe of insects has so many formidable enemies among other 

 orders as the plant lice. They are preyed upon by certain of the fossorial 

 Hymenoptera, which carry them off to their burrows as food for their 

 larva?, and as they sting and paralyze but do not kill them the larvae are 

 provided with a sufficient supply of fresh meat as long as they require it. 

 Large numbers of species of Bracomder, Cbalcididce and other parasitic 

 Hymenoptera deposit eggs in their bodies, and in this way destroy myriads 

 of them. The larvae of the Lacewing flies among the Neuroptera, the 

 Syrphida among the Diptera, and the Coccinellidce among the Coleoptera 

 also devour enormous multitudes, and when a systematic attack is made 

 upon them by the horticulturist he is far more likely to destroy his 

 friends than his foes, as they are much more easy for him to get at, and 

 thus he too often stops their beneficent operations in blissful ignorance 

 of their very existence. 



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