234 



THE AGRICULTURAL NEWS. 



July 2-4, 1909. 



INSECT NOTES. 



Hymenoptera. 



Several of the natural orders of insects have been 

 briefly discussed in recent numbers of the Agricultural 

 Nev:». The Hj-menoptera is the last of these to be 

 dealt with in this series of articles. 



The insects which belong to the Hymenoptera are for 

 the incst part easily recognized and distinguished from those 

 of other orders. The ants, bees, and wasps comprise one 

 division of the order, while the other is composed lar^<ely of 

 parasitic insects, which are often so very small that they 

 would never be seen except by those who are interested in 

 ■them and are making a distinct effort to find them. 



The Hymenoptera may safely be called the order of 

 beneficial insects. There are, of course, injurious insects in 

 this order, but these are a very small proportion of the whole, 

 and in the West Indies they are very seldom seen. 



The honey bee, which provides' honey and wa.v, is 

 pcrhai'S the only member of this order which furnishes 

 a product directly useful to man : but the other members of 

 the same group, the wasps, which in some cases feed their 

 young with insects, and in others .store their nests with 

 spiders and caterpillars, are berieficial. The ants are useful 

 as scavengers. They are a great nuisance, especially in rhe 

 tropics, but are more often beneficial than directly injurious. 



The parasitic Hymenoptera are e.xtremely useful on 

 account of their habit of depositing their eggs in or on the 

 bodies of other insects. The parasite is developed at the 

 expense of the host. No insects are too large, and it might 

 almost be said that none are too small, to be hosts for some 

 parasites. The enormous benefit arising from the parasitic 

 habit can scarcely be realized. It might be much greater, 

 however, were it not for the fact that in choosing their 

 host, many parasitic insects attack other parasites. 



The adult Hymenoptei-a have two pairs of membranous 

 wings .similar in structure and appearance, the first pair 

 being slightly larger than the second. The head, thorax, and 

 abdomen are easily distinguished, the latter, in the case of 

 the mason bee, being attached by a very long, slender pedicel. 



The metamorphosis of the insects of this order is com- 

 plete, the four stages — egg, larva, pupa, and adult — being 

 distinct and w-ell defined. 



The Hymenoptera are the only insects which take care 

 of their young during the helple.ss and inactive portion of 

 their lives. The ants, bees, and wasps, all care for tlieir young, 

 feeding them, often moving them from place to place, and 

 even sealing up- the cells when the larvae are ready to 

 pupate. There are in the West Indies but few species 

 of bees. The honey bee {Api.'f iiiclliu-rd) is of course to be 

 found both wild and domesticated. The wood-boring bee 

 (Xp/ornpa finiliriala) is the largest of our bees. It lives in 

 .stumps, posts, rails, and dead branches of trees, boring out 

 a dee|) tunnel in which the eggs are laid. The main portion 

 of the tunnel is vortical and divided into several compart- 

 ments, one above another. An egg is laid at the bottom of 

 the tunnel, a supply of food is provided for the sustenance 

 of the larva, and a cross-wall built. This process of storing 

 food and laying an egg is rejjeated until the tunnel is all 

 divided up into chambers or cells. The cuiinus fact is, that 

 the insect developing from the first laid egg at the bottom 

 is the last one to get out of the tunnel. 'I'he male of this 

 bee is of a pale rust-red colour, while the female, which is the 



more often seen, is shining black. A smaller form of wood- 

 boring bee {Xi/locojiaj^eneipennis) is sometimes found in the 

 West Indies. 



The leaf-cutting bees {.Ve;/achi/e sjjp.) often seriously 

 injure ro.ses and other garden plants, and even completely 

 defoliate such large trees as the silk cotton. They cut out 

 circular pieces of leaf, of which they build their cylindrical 

 nests. 



The wasjis are very interesting. They include the wild 

 bee, cow bee, and Jack Spaniard, of the social wasps, and 

 a long list of interesting, often brilliantly coloured solitary 

 wasps. The social wasps are well known and readily recog- 

 nized. They have a mo.st powerful and painful sting, but their 

 habits are very distinctly beneficial. The nests are built of 

 pajier, which the adult insects make by chewing up fibres 

 collected from wood or bark. The eggs are laid singly in 

 open cells, and the larvae develop in them. The adults bring 

 food, generally insects, and feed the young till they are ready 

 to pupate. The solitary wasps are able to sting spiders and 

 insects in such away as to paralyse them without killing them. 

 These paralysed spiders and insects are used for storing the 

 nests, so that the larvae, which develop later, may have living 

 food. Some of the largest forms of Hymenoptera are found 

 among the solitary wasps, as well as .some of the most 

 brightly coloured. 



The ants are probably known to every dweller in the 

 tropics. They are most often noticed on account of their 

 attacks on foodstuffs and household supplies ; sometimes they 

 are remembered on iiccount of their disagreeable stings. 

 They build their nests in garden and lawn, and foster scale 

 insects and mealy-bugs and plant lice, and, in the case of the 

 parasol ant, the damage resulting from their leaf-cutting 

 depredations is often very great. 



The parasitic Hymenoptera are perhaps the most useful 

 of all the insects in the West Indies. Almost every injurious 

 species of insect has its parasite, often more than one : and 

 without these u.seful forms of life the practice of agriculture 

 would present far greater difficulties than at present. 

 The eggs of the moth borer of the sugar-cane are 

 attacked by I'l ichoi/ntmi/in pretiosa, which attacks the eggs- 

 of many other lejjidopterous insects, including the cotton 

 worm and the arrowrcot worm. The larva and pupa of the 

 cotton worm are attacked by Chalcis ainiulafa, which 

 probably attacks also many other caterpillars. 



A very useful hyinenopterous parasite is that which 

 attacks the black scale of cotton (Lecaiiiiim nii/niiii). Thi.s 

 insect, which has been named Zaloph<Ahrix mirinn, in 

 widely distributed throughout the Lesser Antilles. 



There are many other parasites of .scale insects in the 

 West Indies. Many of these are now being collected for 

 study, and it is expected that our knowledge of this useful 

 class of insects will be considerably increased. 



An exam|)le of a secondaiy parasite is to be found in the 

 case recorded by Mr. C. W. Jeinmett (see AipiciiUural A'eivs^ 

 Vol. VIII, p. 74). Parasites of the cotton worm were sent 

 from Tobago (Chaids anntdata) and a Sarcophagid fiy was 

 found to be parasitic on the cotton worm, but a third 

 parasitic insect {Spilochah-is) was present, and was found to 

 attack the fly. It was a parasite on a parasite. 



A very curious insect sometimes seen in houses, especially 

 walking on the window panes, is Evnnid l<iti'ii/(it<i. This 

 insect has long slender leg.s, and a very small abdomen, 

 attached high U[) on the thorax by a slender pedicel. As it 

 walks, it moves this little abdomen uj) and down with 

 abrupt jerk.s. This is said to be a parasite on the 

 eggs of the cockroach, and in turn it is parasitized by 

 a smaller one. > 



