74 



THE AGRICULTURAL NEWS. 



Maech 6, 1909. 



INSECT NOTES. 



in length tlie insect varies from 3 to G nun. (| to |-incli). Its 

 chief character, however, is founil in tlie hind femora which 

 are enormously swollen. The femora are tipped with yellow^ 

 the tibiae are yellow at each end, and the tegulae — two small 

 cup-like scales at the base of front wings— are also j'ellow. 



The.se insects were keiit in a breeding cage with larvae 

 and pupae of the cotton worm, and they were .soon to be seen, 

 crawling about the cotton leaves, seeking for the host ia 



Fertilizers as Insecticides. 



In the In.secb Note.s in the last number of the 

 Agricultural N'eirs (Vol. VIII, No. 178), mention was 

 made of the experiments started at Antigua by the 

 Entomologist on the staff ot the Imperial Department 

 of Agriculture to devise means of control for the 

 flower-bud maggot of cotton. 



These experiments include the use of connnercial manures, 

 and it is stated that ' in combating insects closely related 

 to the flower-bud maggot it has been found that applications 

 t)f mineral fertilizers have had a decidedly beneficial effect, 

 not only from their usefulness as manures, but from the effect 

 of the mineral salts in solution in the soil.' 



It will, perhaps, be remembered I>y readers of the 

 Agrindtural News that this liower-bud maggot of cotton 

 leaves the flower buds, either before they fall or immediately 

 after, and enters the soil, where the period of [mpation is 

 passed. This is the only time in the whole life cycle of this 

 insect when it e.Kposes itself to remedial measures. 



The adult insect cannot be dealt with ; the egg and 

 the larval stages are passed inside the plant tissue, and so 

 the pupal period of ten to fourteen days offers the only 

 opportunity for reaching the insect with insecticides. 



Vaporite is employed in the hope that the fumes or gases 

 given off in the soil may lie sufficient to cause the death 

 of the insect while in the condition of a pupa. In like 

 manner connnercial manures such as nitrate of soda, suljjhate 

 of ammonia, .sulphate of potash, superpliii.-.phate, A'i-iihosphate, 

 and salt are used in the hope that the .solution (.f these 

 various substances may kill by contact the pupating insect. 



Some Parasites of the Cotton Worm. 



Mr. Thornton, A.R.C.S., of Old (Ir.-mge, Tobago, 

 who wa.s lately connected with the Imperial Depart- 

 ment of Agriculture for the West Itulies, recently sent to 

 the Head Office of the Department two bo.xes contain- 

 ing insects which he had noticed to be parasitic on the 

 cotton worm. These insects were studied and reported 

 upon by ^Ir. Jemmett, and the following account is 

 based on his report. 



The boxes, on being opened, were found to (■ontain, 

 besides the l.irvae and pujuie of the cotton worm, a number 

 of flies belonging to the S.ircophagidae (flesh (lies), and two 

 species of Hymenopteia, <'f which one was identified as 

 Ghaldx orctta, Say, and the either as a species of the genus 

 i<2>iriirlialcis. Most of the unhatclied cotlim worm pupae had 

 8arcophagid cocoons lying against them. These cocoons are 

 quite conspicuou.s, being small, brown, barrel-shaped objects. 

 The Hymenopterous parasites had pupated inside the cotton 

 worm and of course could not be ob.'<erved. Chn/cis orntu 

 has long lieen known to be a parasite of the cott.m worm. 

 It is a small, lilack insect, marked with yellow. It has four 

 vings, with one coi;spicuons vein in each of the front wings ; 



Fio. 11. Clutlrit: nraf.i (greatly enlarged). From Circvlar 

 iVu. .''." ; Bure.iu df Entomology, I'.S. Dept. of Agriculture. 



which to lay their eggs. They were never observed to attack 

 larvae, but could be seen attacking some of the pupae, crawling 

 on them, and sharply inserting their ovipositors into the vic- 

 tims, in sfiite of the struggles of the latter. All the cotton, 

 worm pujiae which were [lut into the cage emerged in a few- 

 days as moths. The younger pupae, i.e., those formed 

 by the larvae which had pupated in the cage, were all para- 

 sitized, and from these, twelve da3's later, emerged, not moths, 

 but the C'halcidae. From this it appears that it is only the 

 young pupae which are attacked by the parasite. 



This insect has been observed in cotton fields at IJnrba- 

 dos ; most likel)-, it is present in all the cotton-growing West 

 Indian islands, and probably exerts a considerable intlui-nci- 

 in lessening the numbers of this pest. 



Xo record could be found of the other Hymenopterou.s 

 insect which is referred to in these notes as a Spinjchiilcis. 

 This in.sect is of slighter build than the last mentioned one ;. 

 it is yellow in colour, and has a shining or polished appear- 

 ance. The abdomen,, which is small and pointed, is attached 

 to the thorax by a distinct stalk. The hind femora are 

 swollen, as is the case with Chalcis ovnta, and the wings and 

 venation are also similar. 



The.se in.sects were placed in a cage with cotton worm 

 larvae and pupae, but they took no notice of the.se latter,, 

 remaining cm the sides of the cage. A few days later, how- 

 ever, one wasob.servcd emerging from one of the Sarcophagid 

 cocoons previously mentioned, and later .several more of these 

 cocoons were fouml to have Siiirwltulria insiilc them. This 

 insect then is shown to be a jjarasite on the Sarcophagid 

 flies; that is to say, it is an example of the secondary parasites'^ 

 which were discussed in the Aiirii-iiliurnl Xeim, Vol. VIII, 

 Xo. 177, under the heading 'Some Beneticial Insects.' The 

 Sarcophagidae arc generally recognized as being parasitic in 

 habit, though it is still not ipiitc settled as to whether they 

 will attack healthy pupae, or oidy those which have already 

 been damaged in .-ome way. In order to find out the habit of 

 these in.sect.s, some Sarcophagid flies were put into a third 



