Current Category » Introduction to Entomology
Study of Techniques of Collections of, Pinning and Preservation of Insects
Collection of insects will help in obtaining first hand information about the different aspects of inset life such as the host plant, mode of egg laying, feeding, growing and nature of inflicting damage etc. A well identified & classified collection will serve as a valuable reference material of the representative insect fauna of the locality.
Equipments: The following equipments are needed for the purpose of collection, pinning and preservation of insects.
1. Insect collecting net
3. Killing bottle
4. Specimen tubes of 10×2.5 cm with cork.
6. Hand lense of 10× 7.
7. Entomological pins of different sizes
8. Insect storing boxes (45×30×6cm.)
9. Pair of scissors
10. Insect setting boards (35×10cm.)
11. Folding knife
12. Camel hair brush
13. Rearing cages
14. Killing & preserving liquid media.
1. Insect Net: This is prepared by fixing securely a wide ring of 30 cm diameter to a meter long wooden handle. A muslin cloth bag of 60 cm length is fixed to this ring. This net should always be kept dry.
2. Aspirator: This comprises of two holed cork fitted in a specimen tube. Two bend glass tubes are inserted through the holes. One tube of provided with rubber tube to one end & muslin cloth to another end. Aspirator is used to collect the small & delicate insects.
3. Killing Bottle: The collected insects are required to be killed quickly for preservation. For this purpose killing bottles are used. These are the wide mouth jars having thick bottom & tightly fitting corks. It is advisable to have a number of bottles of varying sizes.
Ca, K or sodium cyanide or ethyl acetate or chloroform or 70% alcohol are some of the killing agents used in killing bottles. Potassium cyanide is most toxic killing agent. HCN gas is emitted from the cyanide which kills the insects.
The cyanide killing bottle is made by placing a small quantity of potassium cyanide crystals at the bottom of the bottle wrapped in cotton and over this 1.25 cm dry layer of plaster of Paris is poured. It is allowed to set and dry. Then it is covered by means a disc of blotting paper. This will absorb moisture. The following precautions should be taken in respect of killing bottles.
1. It should be well labeled.
2. Ii should be kept tightly closed.
3. Broken cyanide bottle should be disposed off by burning it into the soil.
4. The separate bottle should be used for killing Lepidopterous and hard bodied insects like beetles and grasshoppers.
5. Over-loading of the bottles should be avoided.
The soft bodied insects like aphids, jassids, thrips or larvae are required to be preserved in fluids. The best killing and preserving agent is 70% alcohol. Before preserving larvae in this medium they should be killed in boiling water.
Mounting the Specimen:
A. Relaxing: The collected and killed insect specimens should be immediately mounted otherwise it becomes brittle & breaks in the process. Hence it should be relaxed in relaxation chamber made out of a wide mouthed airtight jar filled with moistened sand adding few drops of carbolic acid to prevent mould formation. The insects are placed in it for a day for proper relaxation.
B. Pinning: The pinning is the best method for preserving hard bodied insects. The pinning facilitates convenient handling of the specimens for study as well as helps for safe and secure storing. The special rust proof steel pins are used for this purpose, which are generally longer and thinner. As a rule the pins are inserted vertically through the line. The bugs are pinned through the scutellum, grasshoppers through pronotum and beetles through the right elytron. It is desirable to keep 3/4th portion of the pin below and 1/4th portion above the insect body.
C. Setting: The pinned specimens are carefully set on insect setting boards and kept for drying in drying chamber for few days. The wings of the lepidopterous insects and those of Odonata, Neuroptera, Hymenoptera and Diptera etc. are required to be spread after pinning. The general rule in this process is to keep the hind margin of fore wings at right angles to the body and push hind wings underneath these fore wings keeping no gap in between.
D. Labeling: The value of specimen depends upon labeling. The label must contain date and locality of collection, scientific name, host plant and collector’s name.
E. Insect Boxes: The pinned insects must be stored in insect boxes for preserving them safely for a longer period. These boxes are made out of seasonal teak wood in such a way that their joints are insect proof and dust proof. The bottom is covered with cork sheet and prepared for easy pinning. The periodical fumigation of these boxes with EDCT, petrol or naphthalene balls is essential to protect the collection from the attack of the museum pests. On drying insect become very brittle. Extreme care is therefore, be exercised in handling these specimens while storing since specimens with broken legs, antennae or wings are of little value. The best time for collecting insects Is the early hours of morning when the insects are not active. Collection immature stage from the host plants and rearing them to obtain adult forms ensures collection of better specimens.
At night many insects are also attracted to the light. Blue light is more attractive than any other.
Current Category » Introduction to Entomology