122 



THE AGRICULTURAL NEWS, 



Apeil 6, 1916. 



INSECT NOTES. 



INSECT PESTS IN BRITISH GUIANA 



An interesting chart entitled, Common Insect Tests of 

 Garden and Field Crops in British Guiana, by G. E. Bodkin, 

 B.A., etc.. Government Economic Biologist, has recently been 

 issued by the Board of Agriculture, British Guiana. 



This chart contains in a condensed form a considerable 

 amount of information with regard to insect pests and their 

 treatment, under suitable headings. The following summary 

 of the contained information is given under the several head- 

 ings of the chart. 



OEioiN OF INSECT PESTS. The sudden increase of any 

 insect to a point where it becomes a pest may be due to three 

 cau.ses: (1) abundant food supply, (2) decrease of natural 

 enemies, (3) favourable climatic conditions. The destruction 

 of birds is often a cause in the increase of insects: the burning 

 of canes before reaping, as practised in British Guiana, results 

 in the destruction of valuable parasites of cane pests. 



LIFE DEVELOPMENT OF istsECTS. Insects may be divided 

 into groups, such as, butterflies and moths, beetles, scale 

 insects, grasshoppers and locusts, ants and plant bugs. 



BUTTERFLIES AND MOTHS. The life of the butterflies and 

 moths include four distinct stages: the egg, the larva 

 (which is called the worm or caterpillar stage), the pupa or 

 chrysalis, and the adult or winged insect. Moths, generally 

 speaking, fly during the night only, and rest in the day, while 

 the butterflies are day fliers. 



Beetles go through the same four changes as the 

 butterflies and moths: the larva generally lives in the ground 

 or in decaying wood or similar concealed situations, and 

 consequently is less well known than the adult. The wings 

 of the adult are concealed beneath a pair of hard wing covers. 

 1 sc.\LE INSECTS. Great variety of form is found among 

 these insects. The usual appearanee is that of a small scale or 

 shell-like body closely adhering to leaves, fruit or bark. The 

 insect itself is usually found beneath the scale or shell-like 

 covering. Scale insect attack is usually accompanietl by 

 black blight. 



(iRAssHoi'PEKs AND LOCUSTS. When first hatched from 

 the egg these have much the same form as the adult insect, 

 only the wings are undeveloped. 



ANTS. Ants invariably live in colonies, forming nests 

 under stones, the bark of trees, beneath boards, or in the 

 ground. They go through tlie same four stages of develoj> 

 ment as the butterflies, which are all to be found in the 

 nests. The adult is the most familiar form. 



PLANT liutis. These occur in a variety of forms. Thoy 

 possess a long proboscis which is carried beneath the body 

 when it is not in use for piercing the plant tissue and 

 sucking sap. They pass through the difl'erent stages seen in 

 the locusts. 



PHKVKNTIVK ANr> I; K.M i;i>i AL MEASUKEs. As a preventive 

 measure, good and careful all round cultivation is recom- 

 mended as es.sential in dealing with pests. 



Remedial measures consist in: — 



1. The exercise of sound common-sense 



2. The use of insecticides. 



3. Hand-picking. 



4. C 111 ti vation methods. 



5. The use of some mechanical contrivance to collect and 



kill the in sects, e.g., trap lights. 

 <). Encourage me nt of bird life and parasites. 



INSECTICIDES. These may be divided into two classes: — 



1. Those that act as stomach poisons. 



2. Those that act by contact or asphyxiation. 



Lead arsenate is mentioned as an example of a stomach 

 poison. ""This may be used in water as a spray, or in a dry 

 form dusted on the plants. When used as a spray the 

 proportions are 4 lb. lead arsenate to 50 gallons water. 



Kerosene emulsion and resin compound are given as 

 examples of contact poisons, with directions for their prepar- 

 ation and use. , 



Carbon bisulphide is given as a substance which acts on 

 insects by asphy.xiation, anil its use for fumigating stored 

 grain is mentioned. 



The central portion of the sheet on which this chart is 

 printed is occupied by information as to the treatment of 

 certain pests. These are given under their crop hosts -or food 

 plants, with the common name of the pest, a popular descrip- 

 tion of the same, and brief suggestions for remedial treatment. 



The following pests of crops are mentioned: — 



sucAE. Giarrt moth borer {Castnia), small moth borer 

 {DvUv'im), leaf-eating worms, weevil borer, mealy-bug, 

 wood ants or .termites. 



RICE. Leaf-eating worms. . 



COCONUT i-Aj^Ms. Borer, scales, leaf-eating worms 

 (Br(issoli'), cockles (beetles). 



PAEA RUBBER. Couchi auts Or umbrella ants, leaf-eating 

 worms, scales, locusts. 



CITRU.S FRUiT.s. Couchi ants or umbrella ants, scale 

 insects. 



EGG PLANT OR BOULANGEE. Leaf-eating beetles. 



Peppees. Leaf-eating worms. 



CASSAVA. Leaf-eating worms. 



sweet POTATOES. Weevils. 



COFFEE. Scale insects, ants. 



CACAO. Scale insects. 



The following accounts of insect pests are copied as 

 examples of the means of describing the pests and suggesting 

 the treatment to be employed. 

 SUGAR-CANE. Giant moth borer, [Cuslnia.) 



Descriptivn. The larva bores into the rooting system, 

 and lower portion of the stem of the cane. It is a large 

 white worm with powerful jaws, about 2i inches in length. 

 The chrysalis is dark brown in colour and is found in 

 a rough cocoon composed of cane fibre. The moth has 

 a wing expanse of about 3 inches. The general colour of the 

 wing is dark brown with a broad transverse stripe across 

 each of the upper and lower wings. The margin of each 

 hind wing has a row of yellow spots. 



The moth flies by day and particularly during the bright 

 sunshine. The eggs are dro|iped singly by the moth, usually 

 in the axils of the leaves. 



Remedies. Numbers of the moths may be caught by 

 means of hand nets at certain limes during the day. Directly 

 after a field of canes has been cut, vigorous search should be 

 made for the worms of the borer in the stumps of the canes, and 

 as many worms and chrysalids as possible thus, secured. 



Birds should be encouraged in Castnia infeited areas, 

 especially the old witch, Kiskeedes, and ■ certain species of 

 Hawks. l\^rches may be erected about the fields for their 

 convenience. 

 SWEET POTATOES. Weevils. 



DexcripUon. Two species of weevils one small and 



