618 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



above-mentioned crops. This line of work 

 had its origin at the California State In- 

 sectary, together with the process of 

 hibernating this and various other species 

 in enormous quantities in artificial cold 

 storage. 



Experiments have been conducted along 

 this line at the Insectary, whereby the 

 Hippodamia convergens has been success- 

 fully kept in hibernation in cold storage, 

 without impairing the vitality of the spe- 

 cies for seven months and 14 days. 



This particular line of work was in- 

 augurated through practical necessity, ow- 

 ing to the fact that the chief obstacle to 

 the raising of cantaloupes in California, 

 especially in Imperial valley, has been the 

 attack of the melon aphis (Aphis gossy- 

 pii), often ruining whole fields in three 

 or four days, and no mechanical or other 

 means of fighting them had been found 

 effective; indeed, it was only possible to 

 get rid of them by destroying the infested 

 vines. 



The use of ladybirds for the destruction 

 of aphids has gradually spread from their 



Fipr. 8. One Hundred and Thirty Pounds of 

 Ladybirds on Pack Mule. Nine miles througb 

 the snow to the pacliing house. 



originally appointed work, until now the 

 Insectary ships crates upon crates to prac- 

 tically every county in the state of Cali- 

 fornia, and to growers of almost every 

 horticultural product subject to the attack 

 of aphid species, even including city (or- 

 namental) street trees and home gardens. 



The particular coccinellids {Hippodamia 

 convergens) used in fighting aphid infest- 

 ations are a species native to California. 

 They are of a predatory habit, and their 

 special prey and chosen food are the 

 aphids, upon which they feed both in the 

 larval and adult stages. 



The best results are obtained by placing 

 colonies in the infested fields or orchards 

 at, or just before, the first appearance of 

 the aphids; the object being to prevent 

 the increase of these destructive insects. 



Again, the female coccinellid, if the 

 natural food is scarce in an orchard or 

 field, is thus forced to search diligently 



for aphids, and will distribute her eggs 

 in proportion to the number of aphids 

 present; whereas, if the colonies were not 

 placed until after the aphids had become 

 abundant, she would deposit practically 

 all her eggs in the same place. The same 

 rule will apply to practically all cultivated 

 crops, and therefore it is important that 

 applicants for colonies of this particular 

 species should place their order early, and 

 again notify the Insectary when the very 

 first aphids are noticed, and ask that their 

 colony be sent them immediately. 



It has been thoroughly demonstrated 

 that by following such a procedure, with 

 the help of the ladybirds, orchards and 

 fields have been kept commercially clear 

 of this obnoxious insect. So great is the 

 demand for ladybirds by growers of 

 melons and all other kinds of fruit, that 

 the Insectary has been obliged to organ- 

 ize, upon a very considerable scale, the 

 work of collecting these insects. 



The enormous amount of work con- 

 nected with the locating, collecting and 

 holding in hibernation, the boxing, crat- 

 ing, shipping and distributing of several 

 tons of live insects is little realized by 

 the average reader. The illustrations 

 accompanying this article, together with 

 the following, will give some idea of how 

 this work is conducted: 



Starting about November 1st, the field 

 men go up into the mountains to locate 

 the hibernating colonies, which are usual- 

 ly found among pine-needles on sunny, 

 well-drained slopes, usually in close prox- 

 imity to running water. They are se- 

 curely hidden, and inexperienced collect- 

 ors may pass and repass directly over 

 such spots and the presence of the colony 

 will never be detected. In fact, the idea 

 generally prevails in the minds of the 

 mountain residents that the beetles come 

 to the sections in the spring, and the 

 idea is scouted that colonies of beetles 

 spend the winter under the snow. 



At this season, however, only a few of 

 the beetles, relatively speaking, are dis- 

 coverable. They are the first arrivals 

 which have sought winter quarters early, 

 but later on the colonies thus started 

 rapidly grow in size. Other ladybirds 

 join them, probably attracted by a pecu- 

 liar insect odor, which they recognize, 

 and so in the course of a few weeks im- 

 mense numbers assemble. 



•Tust how these over-wintering colonies 

 are located, if explained, would hardly be 

 believed by the general reading public. 

 In fact, it is a sort of sense that is hardly 

 subject to analysis. Our field men know, 

 by past experience, where the most likely 

 places are. and how also to find the bee- 

 tles. We can at least immediately tell 

 where they are not. thus eliminating a 

 great deal of unproductive territory from 



