Monday, 29 August 2016

The Black Soldier Fly - Hermetia illucens

 The sort of beastie which is a creature that one should really know more about, but one doesn't.
There are quite a few who do know a good deal, however.  Among the avant-garde of gardeners there are those who are quite familiar with this insect.
Its original home is in the continent of America. Now it is probably found world-wide.  Looking up the recorded distribution in France, I find it is recorded in departments along the Atlantic Coast and here and there elsewhere, but not in the Department of the Lot, till now.

This large fly (16 mms long) was sitting on a window frame, looking almost moribund, which it probably was, for the adult only lives a few days.  It cannot eat and is but a reproductive element in the life cycle, in the same manner that exists with mayflies.  I thought at first that it was a species of horsefly (Tabanid) but the length of the antennae seemed to suggest otherwise.  Then what attracted my attention strikingly were the two transparent discs on the forepart of the abdomen. One can see right through the body like windows.
This insect is, as a larva, a maggot, a voracious scavenger of both plant and animal remains.
Further reading tells me that the insect is actually 'cultivated' to reduce compost and food waste.  The larvae can be used as chicken feed and even it is suggested as human food.
The adults live  for a few days, in which they mate, lay eggs and then die.
The references in general say that it causes no disease problems and is probably most useful in clearing up the waste generated by us humans.

Wednesday, 24 August 2016

Grasshopper hunting wasps.

 In late summer when one opens a window, it is not unusual to find the groove at the bottom packed with pieces of cut hay packaging a number of small 'grasshoppers'.  The green insects are in fact 'sauterelles' as the French call them. To create confusion in English they are called crickets, whilst to make that yet more confusing what the French call criquets, the English call 'grasshoppers'.
Wasp hoard of hay and oak-bush crickets
This mass of sauterelles and hay is placed there by a large black and red wasp named Sphex rufocinctus.  The sauterelles are Meconema meridionalis - In English called the southern oak-bush cricket.  This species is quite tiny rarely reaching 15 mms.  Indeed they are small enough to be confused as larval forms. They tend to hide away during the day underneath the leaves of oak, high up in the trees.  
The crickets are paralysed by the wasp. And into this heap of Hay and crickets, the wasp lays about one egg to every four crickets.  After  some short period the eggs hatch and the larvae commence to eat the food stored for them. That you can see in the photo on the right.
These larvae will then pupate first enveloping themselves in silk rather as caterpillars will do.  The firm dark brown pupae will await there till the next spring.