HOW TO KNOW THE IMMATURE INSECTS 



cause plant galls may be reared by enclosing the seeds or galls in a 

 tight container. Parasitic wasps may be reared from their hosts by 

 keeping the host until the adult parasites emerge. Boring insects can 

 be left in the original food material and kept in a cage until they 

 emerge. 



3. Humidity. — Humidity plays an important part in rearing insects. 

 If the condition inside of the container is too dry the food material 

 becomes unsuitable for the insects. On the other hand, if the humidity 

 is too high, moisture will be deposited on the sides of the container 

 and frequently the death of the insect will result. To adjust the humid- 

 ity of a vial or a bottle, changing of the materials of the stopper is 

 sometimes found practicable. A cork stopper can keep the humidity 

 much higher than a stopper of cotton. Insects that feed on decaying 

 animal matter should have the cage provided with slightly moist soil 

 or sand. 



4. Pupation. — Insects that are being reared often die during the pupal 

 stage. This requires a careful study of the pupation habits. Some in- 

 sects make silk or soil cocoons and some just pupate in the soil with- 

 out forming any covering. Soil must be added to the cage to meet 

 the needs of the insect, otherwise a successful fearing will not be ob- 

 tained. The cocoon should not be removed artificially from its enclos- 

 ed pupa for it is necessary to protect the insect. The over-wintering 

 pupae should be kept in good condition. Cold can kill the pupae and 

 too high temperatures may cause the pupae to emerge too early. 



5. Preserve the different stages. — For life history study, no\ only the 

 different stages and different instars need to be preserved, but also 

 the cast larval skins, pupal cases and cocoons which are very im- 

 portant in scientific study. These should all be carefully labeled. 



6. Recording. — Every change of the insect, both morphological and 

 physiological, should be recorded at once. The student may devise 

 his own form of records but should keep them uniform and with all 

 the necessary details. Careless observations and records are worse 

 than none at all; the latter can not be misinterpreted. 



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